Patent Publication Number: US-10772497-B2

Title: Medical interfaces and other medical devices, systems, and methods for performing eye exams

Description:
RELATED APPLICATIONS 
     This application claims priority benefit under 37 C.F.R. 119(e) to U.S. Provisional Patent Application No. 62/051,237, filed Sep. 16, 2014, U.S. Provisional Patent Application No. 62/050,034, filed Sep. 12, 2014, as well as U.S. Provisional Patent Application No. 62/050,676, filed Sep. 15, 2014. Each of these above-referenced applications are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     Field 
     Embodiments of the present disclosure relate to the field of healthcare, including for example, devices, systems, methods of automating the provision of diagnostic healthcare services to a patient as part of an examination meant to detect disorders or diseases. In some but not all instances, these healthcare services may apply only to eye care encounters, exams, services and eye diseases. 
     Description of the Related Art 
     Many people visiting medical offices often use the same equipment. Cross-contamination has become a problem of increasing concern, especially during certain periods such as flu season. As the provision of healthcare becomes more automated, fewer office personnel may be present to clean devices between uses. Accordingly systems and methods for improving hygiene are desirable. 
     SUMMARY 
     A wide range of embodiments are described herein. In some embodiments, a mask may comprise a distal sheet member having one or more substantially optically transparent sections and a proximal inflatable member having a rear concaved surface that may face a first patient&#39;s face when in use. The rear concaved surface may be configured to conform to contours of the first patient&#39;s face. The inflatable member may have two cavities therein. The two cavities may be generally aligned with the one or more substantially optically transparent sections, and may extend from the rear concaved surface toward the distal sheet member such that the cavities define two openings on the rear concave surface. The rear concave surface may be configured to seal against the first patient&#39;s face such that the first patient&#39;s eyes align with the two cavities, so that the rear concave surface forms seals around a peripheral region of the first patient&#39;s eye sockets that inhibit flow of fluid into and out of the cavities. The mask may further comprise an ocular port providing access to at least one of the two ocular cavities for fluid flow into and out of the at least one of the two ocular cavities and an inflation port providing access to inflate the inflatable member. 
     In various embodiments, the rear concaved surface may be configured to conform to the contours of the first patient&#39;s face with inflation of the inflatable member via the inflation port. The inflatable member may be underinflated and the rear concaved surface may be configured to conform to the contours of the first patient&#39;s face with inflation of the underinflated inflatable member via the inflation port. The rear concaved surface may be configured to conform to the contours of the first patient&#39;s face with application of negative pressure to the inflatable member via the inflation port. The mask may further comprise particulate matter disposed within the inflatable member. The particulate matter may be configured to pack together with application of a negative pressure to the inflatable member via the inflation port, so that the rear concaved surface conforms to the contours of the first patient&#39;s face. 
     In various embodiments, the rear concaved surface may be configured to conform to contours of a second patient&#39;s face, wherein a contour of the second patient&#39;s face is different from a contour of the first patient&#39;s face. The seals may be air-tight. The mask may further comprise a lip extending into at least one of the two cavities from a perimeter of at least one of the two openings, the lip having distal ends curving toward the distal sheet member in a default position, the distal ends configured to move rearwardly such that the lip seals against the user&#39;s face upon introduction of positive pressure into the at least one of the two cavities. The inflatable member may be opaque. 
     In various embodiments, the distal sheet may be configured to interface with a medical device, which may be an eye exam device. The mask may be configured to couple with a docking portion on a medical device. The mask may be configured to couple with the docking portion via a flange that slides into a slot of the docking portion. The inflation port and the ocular port of the mask may be configured to couple with conduit ends on a medical device. The ocular port and the inflation port may include a male portion, wherein the conduit ends on the medical device include a female portion configured to slidably receive the male portion. The ocular port and the inflation port may be configured to couple with the conduit ends on the medical device substantially simultaneously. 
     Some embodiments relate to the utilization of devices that replace, augment or enhance human laborers in a clinical health care setting. These devices may be used alone or in conjunction with other devices used in exams such as exams of the eye. 
     For purposes of this summary, certain aspects, advantages, and novel features of the invention are described herein. It is to be understood that not necessarily all such aspects, advantages, and features may be employed and/or achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other features, aspects and advantages of the present invention are described in detail below with reference to the drawings of various embodiments, which are intended to illustrate and not to limit the invention. The drawings comprise the following figures in which: 
         FIG. 1  schematically illustrates a perspective view of one embodiment of a mask which is inflatable and includes a framework that forms two cavities for the oculars. 
         FIGS. 2 a -2 b    schematically illustrates a mask removably attached to a medical device. 
         FIG. 3  schematically illustrates a user wearing a mask that provides, for example, an interface to a medical device such as a diagnostic device that is used by many patients. 
         FIG. 4  schematically illustrates a perspective view of another embodiment of a mask with an inflatable framework that is partitioned into two separately inflatable sections. 
         FIG. 5  schematically illustrates a cross section of the mask in  FIG. 4  taken along the lines  5 - 5 . 
         FIG. 6  schematically illustrates a perspective view of another embodiment of a mask with a seal around the ocular cavities. 
         FIG. 7 a    schematically illustrates a side view of one embodiment of a mask displaced a first distance from a medical device. 
         FIG. 7 b    schematically illustrates a side view of another embodiment of a mask displaced a second distance from the medical device. 
         FIG. 8  schematically illustrates a schematic diagram of a system for controlling, monitoring, and providing fluid to a mask. 
         FIG. 9  schematically illustrates a schematic diagram an electronic exam portal. 
         FIG. 10  schematically illustrates a healthcare office map. 
         FIG. 11  schematically illustrates a block diagram of a sample healthcare encounter. 
         FIG. 12  schematically illustrates a binocular eye examination system based on optical coherence tomography. 
         FIG. 13  schematically illustrates a display of eye examination data. 
         FIGS. 14A-D  schematically illustrate a mask having optically transparent sections that are tilted or sloped upward or downward and include an anti-reflection (AR) coating to reduce retro-reflection of light from an incident probe beam from an optical coherence tomography instrument back into the instrument. 
         FIGS. 15A and 15B  schematically illustrate the effect of a tilted or sloped window on a probe beam from the OCT instrument which reduces retro-reflection into the optical coherence tomography instrument. 
         FIGS. 15C-E  schematically illustrate the effect of a tilted or sloped window on a mask on the light reflected from an incident OCT probe beam and how tilting or sloping the window beyond the angle of the steepest ray of light from the probe beam can reduce retro-reflection into the optical coherence tomography instrument. 
         FIGS. 16A-D  schematically illustrate a mask having optically transparent sections that are tilted or sloped nasally or temporally to reduce retro-reflection of light from an incident probe beam back into the optical coherence tomography instrument. 
         FIGS. 17A-E  schematically illustrate a curved window on a mask and demonstrates how the location of the window with respect to the focus of the OCT instrument (e.g., oculars or eyepieces) can vary the amount of retro-reflection of light from the optical coherence tomography instrument back into the OCT instrument. 
         FIGS. 18A-D  schematically illustrate a mask having optically transparent sections that are curved to reduce retro-reflection of light from the optical coherence tomography instrument back into the OCT instrument. 
         FIG. 19  schematically illustrate a curved window on a mask disposed forward of a pair of eyes separated by an interpupilary distance wherein the window is increasing sloped more temporal from a center line through the window thereby exhibiting wrap that reduces retro-reflection of light from the optical coherence tomography instrument back into the OCT instrument. 
         FIGS. 20A-D  schematically illustrate a mask having an optical window having wrap as well as curvature in the superior-inferior meridian to reduce retro-reflection of light from the optical coherence tomography instrument back into the OCT instrument. 
         FIGS. 21A-21D, 22, 23, 24, 25A-25D, 26, and 27  schematically illustrate differently shaped mask windows. 
         FIGS. 28A-D  schematically illustrate design considerations in determining the slope of the window at different distances from the centerline through the mask. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Some embodiments disclosed herein provide an inflatable mask that can interface with medical devices, such as medical diagnostic devices, such as optical coherence tomography (“OCT”) devices. The inflatable mask can serve a variety of purposes, including maintaining a barrier between the patient and the medical device to ensure cleanliness and hygiene, providing comfort to the patient, and stabilizing the patient&#39;s location with respect to the machine. In some embodiments, the inflatable mask can form air-tight ocular cavities around the patient&#39;s eyes, allowing for pressurization of the ocular cavities, in order to obtain ocular measurements. Additionally, various embodiments of an automatic portal system and an automated eye examination are disclosed herein. 
     Embodiments of the invention will now be described with reference to the accompanying figures, wherein like numerals refer to like elements throughout. The terminology used in the description presented herein is not intended to be interpreted in any limited or restrictive manner, simply because it is being utilized in conjunction with a detailed description of certain specific embodiments of the invention. Furthermore, embodiments of the invention may comprise several novel features, no single one of which is solely responsible for its desirable attributes or which is essential to practicing the embodiments of the inventions herein described. 
     Inflatable Medical Interface 
     Referring to  FIG. 1 , in one embodiment, a mask  100  includes a distal sheet member (distal portion)  118  which has optically transparent sections  124 , and a proximal inflatable member (proximal portion)  154  having a generally concaved rear surface  122 . In use, the rear concaved surface  122  faces the patient&#39;s face and conforms to the patient&#39;s face, according to some embodiments. As used herein the terms “user” or “patient” or “subject” or “wearer” may be used interchangeably. Still Referring to  FIG. 1 , the inflatable member  154  can have two cavities  160   a ,  160   b  which are aligned with the optically transparent sections  124 . In some embodiments, the cavities  160   a ,  160   b  extend from a distal sheet  118  to the rear concave surface  122  and define two openings  162  on the rear concave surface  122 . In use, the patient&#39;s eyes align with the two cavities  160   a ,  160   b , so that the rear concave surface  122  forms seals around the patient&#39;s eye sockets or face, e.g. forehead and cheeks, inhibiting flow of fluid into and out of the cavities  160   a ,  160   b . In addition, the mask  100  can include ports  170   a - b ,  180   a - b  which provide access to control flow of fluid (e.g. air) into and out of the cavities  160   a ,  160   b.    
     In some embodiments, the mask  100  can interface with a medical device. With reference to  FIGS. 2 a -2 b   , there is illustrated one embodiment whereby the mask  100  is placed on a separate device  112 . In some embodiments, the separate device  112  is a medical device, such as a diagnostic or therapeutic device. In some embodiments, the separate device  112  is an ophthalmic device, such as a device for the eye, and may be an optical coherence tomography device (“OCT”) that may contain a housing and instrumentation contained therein. The mask  100  may be used with a wide range of medical devices  112 , such as for example an OCT device such as disclosed herein, as well as other OCT devices and other medical devices  112 . In some embodiments, the medical device  112  can receive and removably connect to the mask  100 . The mask  100  can be configured to connect to the medical device  112 , adhere to one or more surfaces of the medical device  112 , or be mechanically fixed to the medical device  112 , or be secured to the medical device  112  in any other way (e.g. clamps, straps, pins, screws, hinges, elastic bands, buttons, etc.), such that the mask  100  is removable from the medical device  112  without damaging the mask  100 . 
     In one embodiment, a docking portion  114 , which may include an optical interface such as for example a plate, can be included on the medical device  112 . The docking portion  114  can also include a slot  116  for receiving a mask  100 . In some embodiments, the mask  100  includes a flange  164  that extends laterally outward past a side of the inflatable member  154  on the distal sheet  118  for slideably engaging with the slot  116 . The mask  100  can be inserted into the slot  116  and slide down to a final locking position  120 . In another embodiment, the flange  164  can be on the medical device  112  and the slot  116  can be on the mask  100 . 
     With reference to  FIG. 3 , there is illustrated an example of a mask  100  worn by a user over the user&#39;s eyes. In various embodiments, the mask  100  may be removably attached to the wearer with an adhesive, an elastic band, a Velcro band, a strap, a buckle, a clip, and/or any other suitable fastener or mechanism. In some embodiments, the mask  100  can include mechanisms for both attaching to the wearer and attaching to the medical device  112 . In other embodiments, a patient may use the mask  100  without any straps, bands, etc. that attach to the user. For example, referring to  FIGS. 2 a - b   , the patient may simply move his/her face in alignment and in contact with the mask  100 , which is secured to the medical device  112 . In another embodiment, a patient who has a mask  100  secured to his/her face may position himself/herself properly with respect to the medical device  112 , so that the distal sheet  118  interfaces with the medical device,  112 , and the medical device  112  can take readings. 
     Returning to  FIG. 1 , one embodiment of the mask  100  comprises an inflatable framework  154  having an inflatable chamber  154   a , two cavities  160   a ,  160   b , a frontward surface formed by a distal sheet member  118 , and a rearward surface  122 . It will be understood that “inflatable,” as used herein, can include “deflatable,” and vice versa. Thus, in some embodiments, an “inflatable” framework  154  or chamber  154   a  can be deflatable, and a “deflatable” framework  154  or chamber  154   a  can be inflatable. Referring to  FIG. 1 , cavities  160   a ,  160   b  may extend between the distal sheet member  118  and the rearward surface  122 . In some embodiments, the frontward member  118  includes a window member  124 , which can be substantially optically transparent in some embodiments, with minimal to no effects on the optics of a medical device  112  (e.g. an OCT device) which can interface with the mask  100 , although some embodiments may introduce optical effects. In some embodiments, the distal sheet member  118  can be rigid. In some embodiments, the distal sheet member  118  can be made of polycarbonate, poly(methyl methacrylate), or glass. Other materials can be used. In other embodiments, the distal sheet member  118  can be flexible. The distal sheet member  118  can have a thickness of less than 0.1 mm, 0.1 mm, 0.5 mm, 1 mm, 2 mm, 4 mm, or more. In one embodiment, the window member  124  may be adjacent to the inflatable framework  154 . Thus, the window member  124  may form a frontward surface of a cavity  160   a ,  160   b . Further, the window member  124  may be aligned with the cavities  160   a ,  160   b . In addition, the cavities  160   a ,  160   b  can define openings on the rearward surface, defined by perimeters  162 . Referring to  FIG. 4 , the inflatable framework  154  can have two separately inflatable chambers  150   a ,  150   b . Still referring to  FIG. 4 , in one embodiment, one inflatable chamber  150   a  can have a cavity  160   a  therein, and another inflatable chamber  150   b  can have another cavity  160   b  therein. 
     The distal sheet member  118  may be substantially flat and the rearward surface  122  may be generally curved and concave according to one embodiment. Referring to  FIG. 4 , in one embodiment the thickness of the mask  100  is thinnest at the center  156  and thickest toward the outer edges  158 , with the thickness decreasing from the outer edges  158  toward the center  156 , thereby defining a curved and concave rearward surface  122 . 
     During use, a patient&#39;s face is brought in contact with the rearward surface  122  of the mask, such that the patient&#39;s eyes are aligned with the cavities  160   a ,  160   b , and the patient “sees” into the cavities  160   a ,  160   b . Thus in some embodiments, the cavities  160   a ,  160   b  may be referred to as ocular cavities  160   a ,  160   b . In one embodiment, only the portion of the distal sheet member  118  that aligns with the patient&#39;s eyes may be optically transparent, with other portions opaque or non-transparent. 
     In some embodiments, the rear concaved surface  122  of the mask  100  can seal against a patient&#39;s face around the general area surrounding the patient&#39;s eyes sockets, thereby forming a seal around the patient&#39;s eye sockets. The seal may be air-tight and liquid-tight according to some embodiments. In some embodiments, a seal may be formed between the user and the mask  100  without the need for assistance from additional personnel. In some embodiments, various portions of the patient&#39;s face can form the seal around the ocular cavities  160   a ,  160   b . For example, the patient&#39;s forehead, cheekbones, and/or nasal bridge (e.g. frontal bone, supraorbital foramen, zygomatic bone, maxilla, nasal bone) can form a seal around the ocular cavities  160   a ,  160   b . As used herein, reference to a “peripheral region” around the eye socket shall refer to any combination of the above. 
       FIG. 5  illustrates a top view of a patient wearing a mask  100 . The mask  100  in  FIG. 5  is a cross-section of the mask  100  taken along line  5 - 5  in  FIG. 4 . Referring to  FIG. 5 , as seen from the view of the patient, the mask  100  comprises a right cavity  160   b , such as a right ocular right cavity, a left cavity  160   a , such as a left ocular cavity, a right inflatable chamber  150   b , and a left inflatable chamber  150   b . The walls  172  of the ocular cavities  160   a ,  160   b , the window members  124 , and the head of the user  195  may form an air-tight enclosed area. The head of the user  195  (e.g. the peripheral region around the user&#39;s eye sockets) forms a seal with the rearward perimeters  162  of the cavities  160   a ,  160   b , thus allowing the cavities  160   a ,  160   b  to hold air or fluid. This seal may be capable of holding air or fluid pressures of, for example, 0.5 psi, 1 psi, or 5 psi or pressures therebetween. Higher or lower pressures are also possible. 
     Still referring to  FIG. 5 , some embodiments include inlet assemblies  155   a ,  155   b . The inlet assemblies may include ports  170   a - b ,  180   a - b , allowing access to the inflatable chambers  150   a ,  150   b , and/or the cavities  160   a ,  160   b.    
     Air, fluid, and/or other substances can be introduced into the ocular cavities  160   a ,  160   b , via ports  180   a ,  180   b ,  185   a ,  185   b . Air may be introduced into the left ocular cavity  160   a  by supplying an air source (e.g. via a pump) to the port at  180   a . Thus, following the path of the air, the air may enter the port at  180   a , then exit the port at  185   a  and into the leftocular cavity  160   a  ( 180   a  and  185   b  represent two ends of the same path). Similarly, regarding the right ocular cavity  160   b , air may enter the port at  180   b , then exit the port at  185   b  and into the right ocular cavity  160   b.    
     Accordingly, in some embodiments, pressure inside the ocular cavities  160   a ,  160   b  may be controlled by adjusting the amount of air into and out of the ports  180   a ,  180   b . Further, the air tight seal formed between the patient&#39;s face and the mask  100  can prevent unwanted leaks into or out of the ocular cavities  160   a ,  160   b . This can be advantageous when air or fluid is used to challenge or test a body function. For example, air pumped into sealed air chamber cavities  160   a ,  160   b  in front of the eye can create positive pressure which can be used to press on the eye for the purposes of measuring the force of globe retropulsion or measuring intraocular pressure. In addition, air can be directed to the cornea, which is imaged with OCT. In some embodiments, air is pumped into the ocular cavities  160   a ,  160   b  to achieve a pressure of up to 1-2 psi. In some embodiments, the air supplied to the ocular cavities  160   a ,  160   b  is supplied by ambient surroundings, such as the ambient air in a clinical room using for example a pump. 
     In some embodiments, chamber ports  170   a ,  170   b ,  175   a ,  175   b  provide access to inflatable chambers  150   a ,  150   b  for inflating or deflating the chambers  150   a ,  150   b . The chambers  150   a ,  150   b  may be inflated by introducing an air source (e.g. via a pump) to the ports at  170   a ,  180   a . Thus, for example, following the path of the air, the air may enter the port at  170   a , then exit the port at  175   a  and into the left inflatable chamber  150   a , thereby inflating that chamber  150   a . The right chamber  150   b  may be inflated in a similar manner. Negative pressure (e.g. a vacuum) can be applied to the ports  170   a ,  170   b  connected to the inflatable chambers  150   a ,  150   b , thereby deflating the chambers  150   a ,  150   b . As used herein, “deflating” shall include applying negative pressure. 
     In some embodiments, inflating the chambers  150   a ,  150   b  can cause the mask  100  to conform to the contours of a user&#39;s face. In addition, deflating the chambers  150   a ,  150   b  can cause the mask  100  to conform to the contours of a user&#39;s face. Further, inflating or deflating the chambers  150   a ,  150   b  can adjust a thickness of the mask  100 , thus changing the distance between a user (who may face the rear concaved surface  122 ) and a medical device  112  (which may be interfaced with the distal sheet member  118 ). 
     In various embodiments, a port  170   a - b ,  180   a - b  is provided for each chamber  150   a ,  150   b  and cavity  160   a ,  160   b . For example, referring to  FIG. 5 , there is illustrated a port  185   b  for the right cavity, a port  175   b  for the right inflatable chamber  150   b , a port  185   a  for the left cavity  160   a , and a port  175   a  for the left inflatable chamber  150   a.    
     In one embodiment, two ports may be provided for one inflatable framework  154 . For example, returning to  FIG. 1 , one port  170   b  is provided on the right side of the inflatable framework  154 , and another port  170   a  is provided on the left side of the inflatable framework  154 . Providing two ports for one chamber  154  can help to equalize the distribution of substances (e.g. air or fluid) in the chamber  154  by allowing access to the chamber  154  at different regions. In one embodiment, the inflatable framework  154  does not include any ports. For example, the inflatable framework  154  may be pre-formed as desired, by filling it with a desired volume of fluid or air. Ports  170   a - b ,  180   a - b  may be added, removed, arranged, or configured in any suitable manner. 
     In some embodiments, the mask  100  advantageously can conform to a patient&#39;s face, thereby allowing the formation of a complete air-tight seal between the peripheral region around a user&#39;s eye sockets and the rear concaved surface  122  around the ocular cavities  160   a ,  160   b . Accordingly, the rearward perimeter  162  of the cavities  160   a ,  160   b  can be configured to sealingly engage a periphery of a patient&#39;s eye socket. In some embodiments, the mask  100  includes a recess  168  (see e.g.  FIGS. 1, 4, 6 ), allowing room for a patient&#39;s nose, so that the mask  100  forms a seal against the parts of a patient&#39;s face with a lower degree of curvature, increasing the surface area of the patient&#39;s face to which the mask  100  conforms. 
     In one embodiment, the air-tight seal can be formed by inflating the inflatable framework  154 . In some embodiments, the inflatable framework  154  can resemble a bag. In some embodiments, a mask  100  with a relatively deflated framework  154  is provided to a patient. Because the bag  154  is deflated, it may exhibit some “slack.” The patient&#39;s face may be brought in contact with the mask  100 , and then the bag  154  may be inflated, causing the bag  154  to inflate around the contours of the patient&#39;s face and thereby conform to the patient&#39;s face. Accordingly, a complete air-tight seal can be formed between the patient&#39;s face and the rear concaved surface  122  around the ocular cavities  160   a ,  160   b . The bag  154  may be inflated by introducing air, gas, fluid, gel, or any other suitable substance. In addition, the bag  154  can be deflated, causing the mask  100  to disengage from the patient&#39;s face, according to one embodiment. 
     In one embodiment, an air-tight seal is formed by applying a vacuum to the inflatable framework  154 . In some embodiments, when the framework  154  is filled with particulate matter, such as coffee grounds, a plasmoid transformation to a semi-solid but form-fitting filler can be achieved by subjecting the particulate matter to a vacuum. For example, the framework  154  can be molded into shape easily when particulate matter is loosely contained in the framework  154 , similar to a bean bag. A patient&#39;s face may then be brought into contact with the mask  100 . Applying a vacuum to the bag  154  causes the particulate matter to pack tightly, thereby causing the bag  154  to conform to the contours of a patient&#39;s face. The tightly packed particulate matter can thus undergo a plasmoid transformation to a solid, while still allowing the framework  154  to conform to the patient&#39;s face and create an air-tight seal. 
     To facilitate the seal between a patient and the cavities  160   a ,  160   b , the mask  100  can be configured with a lip  194  around the perimeter  162  of a cavity  160   a ,  160   b , as illustrated in  FIG. 6 .  FIG. 6  illustrates a lip  194  with a cut-away portion  161  showing the curvature of the lip  194 . In one embodiment, the lip  194  comprises a first end  196  attached to the perimeter  162  of the cavity  160   a ,  160   b  and a second end  198  extending partially into the cavity  160   a ,  160   b . In one embodiment, the edge  198  of the lip  194  may extend more or less and curl inward, as illustrated in  FIG. 6 . In one embodiment, the first end  196  and second end  198  define a curve, such that the lip  194  curls inwardly partially into the cavity  160   a ,  160   b . Further, the lip  194  can be flexible and configured to extend in a rearward direction (e.g. toward the rearward surface  122 ). Thus, when pressure is introduced inside the cavity  160   a ,  160   b , and pressure exerts a force in a rearward direction, the lip  194  can move rearwardly. When the inflatable framework  154  is sealed with a peripheral region around a user&#39;s eye socket, and the lip  194  moves rearwardly, the lip  194  can seal against the user&#39;s eye socket, preventing pressure from escaping. 
     In some embodiments, the mask  100  can be configured to be comfortable by filling the chambers  160   a ,  160   b  with soft gel fillers, particulate fillers such as foam beads or sand, or air fillers. 
     In one embodiment, the mask  100  can be custom made to fit the specific patient using it. For example, the mask  100  may be molded for a specific patient in a clinic. Thus, the mask  100  can be uniquely customized for a particular patient according to one embodiment. In another embodiment, the mask  100  is a “one size fits all” mask  100 . Other embodiments are possible, including differential sizing based on age, height or facial structure. In some embodiments, the mask  100  is pre-inflated. In addition, air-tight seals can be formed between the rear curved surface  122  of the mask around the ocular cavities  160   a ,  160   b  and the peripheral region around a patient&#39;s eye sockets (e.g. via a lip) when the mask  100  is pre-inflated. 
       FIGS. 7 a -7 b    illustrate side views of a user with a mask  100  being examined or treated by a medical device  112  according to one embodiment. 
     It will be appreciated that the  FIGS. 7 a -7 b    are schematic drawings and may possibly exaggerate the variation in size for illustrative purposes. The medical device  112  shown in  FIGS. 7 a -7 b    can be an OCT device. Inflating the mask  100  can increase the thickness of the mask  100 , so that the mask  100  can move the patient toward or away from the device  112  when it is deflated or inflated respectively. For example,  FIG. 7 a    illustrates a relatively deflated mask  100 , with a user relatively close to the device  112 .  FIG. 7 b    illustrates a relatively inflated mask  100 , with the user relatively farther from the mask  100 . “Inflating” or “inflated” may include a mask  100  in a fully inflated state, or a mask  100  in a less than fully inflated state, but still in a state that is more inflated relative to a previous state (e.g. a deflated state) or at least partially inflated. Similarly, “deflating” or “deflated” may include a mask  100  in a fully deflated state, or a mask  100  in a less than fully deflated state, but still in a state that is more deflated relative to a previous state (e.g. an inflated state) or at least partially deflated. 
     A patient location sensor  166  can be included in order to detect how close or how far the user is from the medical device  112 . If the user is not at a desired distance from the device  112 , the framework  154  on the mask  100  can be inflated or deflated to bring the user to the desired distance. Any variety of sensors  166  can be used to detect the distance between the user and the medical device  112 , according to sensors known in the art. In one embodiment, a patient location sensor  166  can be included with the medical device  112  in alignment with the user&#39;s forehead, as illustrated in  FIGS. 7 a -7 b   . Thus, the location sensor  166  can measure, for example, the distance or relative distance from the forehead to the medical device  112 . In one embodiment, the sensor  166  can be a switch, which can be actuated (e.g. activated or depressed) when the user&#39;s forehead presses against the switch when the user is close to the medical device  112 . In addition, other types of sensors in different locations could measure the distance between the user and the medical device  112 . In one embodiment, the location sensor  166  is not placed on the medical device  112 , but is placed in a location that can still detect the distance between the user and the medical device  112  (e.g. on the walls of a room in which the medical device  112  is located). In one embodiment, the information regarding the distance between the user and the medical device  112  is provided by an OCT device. 
       FIG. 8  illustrates a system  174  for controlling, monitoring, and providing air to the inflatable mask  100 . The system  174  can be used to control a patient&#39;s distance from the medical device  112 , the patient&#39;s movement to and from the medical device  112 , the seal between the mask  100  and the patient&#39;s face, and/or pressure in the ocular cavities  160   a ,  160   b  of the mask  100 . 
     Referring to  FIG. 8 , the system  174  can include pumps  176 , an air source  176 , conduits  178 , valves  182 , pressure sensors  188 , flow sensors  188  and/or processors (not shown). In addition, air into and out of the inflatable chambers  150   a ,  150   b  and/or cavities  160   a ,  160   b  can be controlled by similar components. Referring to  FIG. 7 b   , the air source/pump  176 , valves  182 , sensors  188 , and the mask  100  can be in fluid communication with each other via conduits  178 . In addition, the air source/pump  176 , valves  182 , and sensors  188  can be in electronic communication with a processor. Further, the processor can be in communication with electronics associated with a medical device  112 , such as an OCT device. 
     In some embodiments, the air source/pump  176 , conduits  178 , valves  182 , sensors  188 , and processors can be contained within a single unit, such as a medical device  112 . In other embodiments, the components may be spread out across several devices external to a medical device  112 . 
     Referring to  FIG. 8 , the mask  100  can be connected to an air source/pump  176 , which can comprise compressed air, ambient air from the environment of the mask (e.g. in a clinical room), a reservoir, a sink (e.g. for providing water to the mask  100 ), an automatic pump, manual pump, hand pump, dispenser, or any other suitable air source/pump. 
     Valves  182  can also be included in the system  174  for increasing, decreasing, stopping, starting, changing the direction, or otherwise affecting the flow of air within the system  174 . In some embodiments, the valves  182  can direct air to an exhaust port, in order to vent air in the cavities  160   a ,  160   b  or inflatable chambers  150   a ,  150   b . In some embodiments, valves  182  are not included in the ports  170   a - b ,  180   a - b  of the mask  100 , and are external to the mask  100 . In some embodiments, valves  182  can be included in the ports  170   a - b ,  180   a - b  of the mask  100 . 
     In some embodiments, the system can also include an ocular pressure sensor  186  to sense the pressure inside the ocular cavities  160   a ,  160   b . Readings from the pressure sensor  186  can be used for intraocular pressure and retropulsion measurements. In addition, the system  174  can include a chamber pressure sensor  184 . In some embodiments, the chamber pressure sensor  184  can be used to determine whether a patient is pressing their face against the mask  100 , or how hard the patient is pressing their face against the mask  100 . 
     A flow sensor  188  can also be provided to measure the volume of flow into and out of the ocular cavities  160   a ,  160   b  and inflatable chambers  150   a ,  150   b . Flow sensors  188  may be useful when, for example, the inflatable chamber  150   a ,  150   b  is underinflated such that the pressure inside the inflatable chamber equals atmospheric pressure. In such a case, pressure sensors  188  may not be useful but a flow sensor  188  can measure the volume of fluid pumped into the inflatable chamber  150   a ,  150   b . In some embodiments, one set of sensors can be provided for the ocular cavities  160   a ,  160   b , and another set of sensors can be provided for the inflatable chambers  150   a ,  150   b.    
     Referring to  FIG. 8 , the conduits  178  can convey the flow of air (or gas, liquid, gel, etc.) between the pump/air source  176 , valves  182 , sensors  188 , and the mask  100 . In some embodiments, the valves  182  can be downstream of the pump/air source  176 , the sensors  188  can be downstream of the valves  182 , and the mask  100  can be downstream of the sensors  188 . 
     In some embodiments, the conduit  178  terminates at conduit ends  192 , shown in  FIGS. 2 a -2 b   . The conduit ends  192  can be designed to couple with the ports  170   a - b ,  180   a - b  of the mask  100 . Referring to  FIGS. 2 a - b   , in some embodiments, the ports  170   a - b ,  180   a - b  of the mask  100  can include a male portion (e.g. a luer lock taper connector), and the conduit ends  192  can include a female portion. 
     In some embodiments, the ports  170   a - b ,  180   a - b  of the mask  100  can include a female portion, and the conduit ends  192  can include a male portion. In addition, the conduit ends  192  and the ports  170   a - b ,  180   a - b  can contain flanges, tubings, or any other mechanism for coupling with each other. When the ports  170   a - b ,  180   a - b  are coupled to the conduit ends  192 , an air-tight seal for fluid flow between the mask  100  and the system can be created. 
     Referring to  FIG. 2 a   , in some embodiments, one movement (e.g. pressing the mask  100  down in the direction of the arrow  199 ) can connect all four ports  170   a - b ,  180   a - b  to the conduit ends  192  at the same time. In some embodiments, the conduit ends  192  extend to the exterior of the medical device  112 , and the conduits  178  can be connected to the exterior ports  170   a - b ,  180   a - b  one at a time. In some embodiments, the conduits ends  192  are located on the medical device  112 , and a separate conduit piece can connect the conduit ends  192  to the external ports  170   a - b ,  180   a - b.    
     In some embodiments, the system  174  can be used in clinical settings, such as during a medical visit (e.g. a medical examination). The components can be utilized in a variety of different ways and combinations during the medical treatment. 
     For example, during a medical diagnostic or treatment, referring to  FIG. 2 a   , the mask  100  can be interfaced with the medical device  112  by aligning the ports  170   a - b ,  180   a - b  of the mask  100  with the conduit ends  192  in the medical device  112 , and pushing down on the mask  100 . 
     The patient&#39;s head can be brought into contact with the rear concaved surface  122  of the mask  100 , and system  174  can inflate or deflate the inflatable chambers  150   a ,  150   b , so that the mask  100  conforms to the patient&#39;s face, thereby forming an air-tight seal around the ocular cavities  160   a ,  160   b.    
     During the procedure, the system  174  can change the pressure in the air-tight ocular cavities  160   a ,  160   b  by a desired amount depending on the medical examination being taken. The pressure sensor  186  can sense the amount of pressure in the ocular cavities  160   a ,  160   b , and send that data to the processor. In addition, the system  174  can vary the pressure in the ocular cavities  160   a ,  160   b  during the procedure. For example, the processor can increase the pump  176  speed or change the valve state  182  so that flow is restricted. 
     Other components in the medical device  112  can also take measurements, such as ocular measurements, which can be combined with the data sent by the pressure sensors. For example, optical imaging components can measure changes in curvature or position of the anterior of the eye and in some embodiments, compare those changes to changes in the position or curvature of posterior of the eye. In addition, changes in the locations and distances of tissues, such as in the eye, can be imaged based on the pressure in cavities  160   a  and  160   b  sensed by the pressure sensors. Thus various pieces of data can be analyzed and processed into meaningful medical information. 
     Further, during the procedure, the system  174  may receive data from a patient location sensor  166  (see e.g.  FIG. 7 a -7 b   ) indicating the distance between the patient and the medical device  112 . The processor may determine that the patient should be positioned closer to or farther away from the medical device  112 , in order to obtain more accurate and precise readings. Thus, the processor may use the location of the patient to modulate the inflation or deflation of the mask  100  more or less (e.g. by changing pump speed, changing valve state, etc.), in order to bring the patient closer to or farther away from the medical device  112 . 
     In some embodiments, the processor can switch on the pump/air source  176  and open the valves  182  to introduce air into the ocular cavities  160   a ,  160   b  or inflatable chambers  150   a ,  150   b  according to a preset pressure or flow volume goal. In addition, flow in the system can be reversed to deflate the inflatable chambers  150   a ,  150   b.    
     The mask  100  may include a mechanism for easily identifying a patient according to one embodiment. For example, the mask  100  may include an RFID tag, bar code or QR code, or other physical embodiment, to identify the wearer to other devices. Thus, for example, when a patient with a certain mask  100  nears the medical device  112 , the system can determine who the patient is, and execute instructions tailored for the patient (e.g. how much air is needed to properly inflate the framework  154 , how much pressure should be applied to the ocular cavities  160   a ,  160   b , what readings the medical device  112  should take, etc.) 
     The mask  100  can be made of a material, such as plastic (e.g. polyethylene, PVC), rubber paper, or any other suitable material. In various embodiments, the mask  100  can be configured to be disposable by making it out of inexpensive materials such as paper, rubber or plastic. In various embodiments, the mask  100  can be configured to be reusable and easily cleaned either by the wearer or by another person. 
     In some embodiments, the mask  100  can provide a barrier between the patient and the medical device  112 , increasing cleanliness and serving hygienic purposes. 
     In one embodiment, the mask  100  can be configured to create a barrier to external or ambient light, such as by constructing the mask  100  out of opaque materials that block light transmission. Accordingly, the mask  100  can prevent ambient light from interfering with medical examination measurements, such as optical devices, and ensure the integrity of those measurements. 
     Although examples are provided with reference to “air” (e.g. introducing air into the inflatable chamber, introducing air into the ocular cavities), it will be appreciated that other substances besides air can be used, such as gas, fluids, gel, and particulate matter. 
     Although examples are provided with reference to a mask  100  for a binocular system, it will be appreciated that the embodiments disclosed herein can be adapted for a mono-ocular system. Thus, in one embodiment, the mask  100  includes an inflatable framework  154  defining one cavity instead of two, and that cavity can form a seal against the periphery of one eye socket. Further, while examples are provided with reference to eye sockets and eye examinations, it will be appreciated that the embodiments disclosed herein can be used with other tissues and medical applications. 
     In other embodiments, an inflatable device may cover different body tissues such as gloves for the hands, stockings for the feet or a hat for the head. In various embodiments, the inflatable device may include a cavity similar to the ocular cavity in the mask and may have at least one port to provide access to the cavity and change pressure therein or inflow gas therein or outflow gas therefrom, as well as a port to inflate the inflatable devices. 
     The inflatable mask can be used in a wide variety of clinical settings, including medical examinations and encounters that may be assisted by automated systems. Various embodiments of an automatic encounter portal are described below. 
     Electronic Encounter Portal 
     Medical encounters can be commonly comprised of administrative tasks, collection of examination data, analysis of exam data, and formation of an assessment and plan by the healthcare provider. In this context, a healthcare provider may be a licensed healthcare practitioner, such as a medical doctor or optometrist, allowed by law or regulation to provide healthcare services to patients. Examinations may be comprised of numerous individual tests or services that provide information for a healthcare provider to use to make a diagnosis, recommend treatment, and plan follow-up. The data from these tests that are collected for use by healthcare providers can be broken down into three rough categories: historical data, functional data and physical data. 
     Historical data can be collected in many ways including as a verbal person-to-person interview, a written questionnaire read and answered by the patient, or a set of questions posed by an electronic device either verbally or visually. Typical categories of historical information that are obtained in medical exams can include but are not limited to a chief complaint, history of present illness, past medical history, past ocular history, medications, allergies, social history, occupational history, family history, sexual history and a review of systems. 
     Functional data can be collected through individual tests of function and can be documented with numbers, symbols or categorical labels. Examples of general medical functions can include but are not limited to measurements of blood pressure, pulse, respiratory rate, cognitive ability, gait and coordination. Ophthalmic functions that may be tested during an exam can include but are not limited to measurements of vision, refractive error, intraocular pressure, pupillary reactions, visual fields, ocular motility and alignment, ocular sensation, distortion testing, reading speed, contrast sensitivity, stereoacuity, and foveal suppression. 
     Physical data can capture the physical states of body tissues and can be collected in many forms, including imaging, descriptions or drawings, or other physical measurements. This may be accomplished with simple measurement tools such as rulers and scales. It may also be accomplished with imaging devices, such as color photography, computed tomography, magnetic resonance imaging, and optical coherence tomography (OCT). Other means to measure physical states are possible. Physical measurements in general medical exams can include height, weight, waist circumference, hair color, and organ size. Ophthalmic structural measurements can include but are not limited to slit lamp biomicroscopy, retinal OCT, exophthalmometry, biometry, and ultrasound. 
     Currently, almost all of the individual tests that make up a medical examination are conducted by a human laborer often through the operation of a device. Whether this person is a healthcare provider or an allied healthcare professional, these laborers can be expensive, can often produce subjective results, and can have limitations on their working capacity and efficiency. Given the labor intensive nature of exams, healthcare care practices (which may also be referred to herein as “clinics” or “offices”) and in particular eye care practices often employ numerous ancillary staff members for every healthcare provider and dedicate large areas of office space for waiting rooms, diagnostic equipment rooms and exam rooms. All combined, these overhead costs make healthcare expensive, inefficient and often prone to errors. 
     Automation is a well-known way of improving efficiency and capacity as well as reducing unit costs. Patient-operated or entirely operator-less devices may be preferable as labor costs increase and the need for objective, reproducible, digital, quantitative data increases. 
     With reference to  FIG. 9 , there is illustrated one embodiment of an electronic encounter portal. The encounter module  200  can be an electronic device that may be comprised of, for example, data storage, communication, or computer code execution capabilities and may contain information on patients registered for a healthcare encounter in an office. 
     The office interface  210  can be comprised of software that may be used by people to interact with the encounter module  200 . Other software may also be included in the office interface  210 . In one embodiment, the office interface  210  also can be comprised of an electronic device, such as a computer, tablet device or smartphone. In various embodiments, office staff can use the office interface  210  to, for example, create records or enter patient data into the encounter module  200  for patients who register in the clinic. This data entry can be enabled in many ways, including for example, manual entry, entry by copying previously-entered data from an office database  220 , or entry using a unique identifier that can be compared to an office database  220  or external database  230 , such as an Internet or cloud-based database, to retrieve pre-entered data for a patient matching that unique identifier. In one embodiment, registration can be completed with a code, such as an encounter code, in a fashion similar to checking in for an airline flight at an airport. This code could, for example, by linked to patient or provider information required for registration purposes. 
     The office database  220  can be configured to store data from past encounters, as well as other types of data. The external database  230  can be also configured to store at least data from past encounters, as well as other types of data. The encounter module  200  can be configured, for example, to access, copy, modify, delete and add information, such as patient data, to and from the office database  220  and external database  230 . The external database  230  can be configured to, for example, receive, store, retrieve and modify encounter information from other offices. 
     In one embodiment, patients may self-register or check into the clinic by using the office interface  210  to, for example, create an encounter record, enter encounter information manually, select their information from a pre-populated office database  220 , or enter a unique identifier that can be compared to an office  220  or external database  230  to retrieve their other associated data. 
     The encounter module  200  can be configured to contain patient records which may also contain clinic processes  205 . A clinic process  205  can be comprised of, for example, orders from the healthcare provider for the patient&#39;s care. In one embodiment, the orders may indicate the sequence of evaluations and care. For example, a provider may indicate that a given patient should undergo a medical history followed by an examination with various medical devices followed by an assessment by the provider. 
     In one embodiment, the clinic process  205  can be configured to enable alteration of the orders, the order sequence or both the orders and their sequence by, for example, office staff or the provider. Examples of this could include insertion of an educational session about a given disease prior to a discussion with the provider, deletion of a treatment denied by a patient, or switching the sequence of two test procedures. 
     In some embodiments, the prescribed orders themselves may contain lists of prescribed tests to be performed on a given device. For example, as part of a technician work-up order, a provider may prescribe blood pressure and pulse measurement testing to be performed on a patient using a device in the clinic. The order and prescription of these tests may change throughout the encounter having been altered by office staff, the provider, or electronic devices. 
     In one embodiment, a diagnosis or medical history of a patient from the encounter module  200  can be included in the clinic process  205  and may be used, for example, to determine or alter the clinic process  205 . For example, a history of past visits and evaluations may alter the tests that are ordered or the devices that are used during an encounter. 
     In one embodiment of an electronic encounter portal, a tracking system  240  can be configured to enable a component of an electronic encounter system to determine the physical location or position of, for example, patients, providers and staff in the office space. In one embodiment, a component of the electronic encounter system can use data from the tracking system  240  to monitor the progress of patients through a clinic process  205 . In one embodiment, this tracking system  240  can be comprised of a sensing technology, such as a compass, radiofrequency antenna, acoustic sensor, imaging sensor, or GPS sensor that determines the position of the sensor in relation to known objects such as office walls, positioning beacons, WiFi transmitters, GPS satellites, magnetic fields or personnel outfitted with radiofrequency ID tags. 
     The tracking system  240  may also be configured to perform mathematical calculations, such as triangulation, to analyze signals from the sensors. The tracking system may also compare signals from the sensors to databases of known signals collected at a prior date, such as comparing a measured magnetic field to a database of known magnetic fields at every position in the clinic. In some embodiments, this tracking system  240  can also be comprised of an emission technology such as a radiofrequency beacon, to indicate the position of an object in the office space. 
     The tracking system  240  may also be configured to localize the position of a person or object using a known map of the office space as shown in  FIG. 3 . Knowledge of the position of sensors, patients or personnel in an office space map may enable the tracking system  240  to provide information to the encounter module  200  regarding the location of patients, providers or other office personnel in an office space. 
     The tracking system  240  can also be configured to provide position information to other components of the electronic encounter system, such as the office interface  210  or the patient interface  250 , either directly or via an intermediate component such as the encounter module  200 . An example of how this information might be used is to provide status information to a user as to the progress or status of other people in the office. 
     In one embodiment, office personnel can use the office interface  210  to monitor the location or progress of, for example, providers, staff or patients within the office space. This monitoring may include calculation of, for example, time spent in a given location, progress through a clinic process  205 , or current status of activity, such as waiting, working or occupied. This monitoring ability can be advantageous so that office staff can, for example, monitor delays in the provision of patient care or identify recurrent patient flow bottlenecks that can be reduced through optimization of clinic flow. 
     The patient interface  250  can be comprised of software that may be used by patients to interact with the encounter module  200 . In one embodiment, the patient interface  210  can also comprise an electronic device, such as a computer, tablet device or smartphone which can be supplied by the clinic or be supplied by the patient. For the purpose of clarity, in one embodiment, the patient interface  250  may be the patient&#39;s own electronic device, such as a smartphone or computer, that can be configured with patient interface  250  software. In other embodiments, the office interface  210  and the patient interface  250  may be the same device, such as with a mobile tablet computer or smartphone, that can be configured to allow a patient to perform actions of both an office interface  210 , such as registration, and actions of a patient interface  250 , such as viewing patient data or asking electronic questions of office personnel. 
     The encounter module  200  and the patient interface  250  can be configured to interface with various devices  260  in the clinic. These devices  260  can include but are not limited to diagnostic instruments, such as blood pressure monitors, imaging devices or other measurement instruments, or therapeutic devices, such as lasers or injection apparatuses. The encounter module and the patient interface  250  can be configured to send and receive data with these devices  260 . Communication with these devices  260  can be enabled by but is not limited to wired connections, wireless connections and printed methods, such as bar codes or QR codes. 
     With reference to  FIG. 3 , there is illustrated a map of a healthcare office. In one embodiment, the patient can register for a healthcare encounter at the office entrance  300 . In other embodiments, the patient may register for a healthcare encounter at a place other than entrance  300 . In one embodiment, encounter registration can be completed by a human receptionist who may enter information into the encounter module  200  through the office interface  210 . In another embodiment, registration may be completed by the patient for exemplary using an assisted or self-service kiosk configured with an office interface  210 . 
     A kiosk may, for example, be comprised of a location where an untrained user can perform a task or tasks, such as checking in for an appointment or performing a requested test. This kiosk may be comprised of electronics or computer equipment, may be shielded from the view of other people in the same room, may be comprised of seating, and may provide a material result to a user. Other kiosk configurations are possible. 
     In another embodiment, the patient may register for the encounter with an office interface  210 , such as a tablet computer, that is supplied by the clinic and may have been configured with software to interface with the encounter module  200 . In still another embodiment, the user may register for the encounter with their own portable device, such as a mobile phone or tablet computer, that can be configured with software that can allow it to act as either or both an office interface  210  or as a patient interface  250 . 
     In various embodiments, orders or steps in an electronic encounter system can include, for example, asking a patient to sit in waiting area  310 , asking a patient to proceed to testing area  320  or asking a patient to go to clinic area  330 . These orders can be conveyed to the patient by, for example, the patient interface  250  or by office personnel. In one embodiment, the desired disposition for a patient can be determined by a clinic process  205  that may have been entered into the encounter module  200  and communicated to the patient via the patient interface  250  or office personnel. 
     In one embodiment, the patient interface  250  can be configured to use information from the tracking system  240  for example, to determine the location of the patient in the clinic, to determine the next planned location for a patient from a clinic process  205  in the encounter module  200 , or to communicate directions to a patient using the patient interface  250 . 
     Referring to  FIG. 10 , in one embodiment  340 , a line can be drawn on a schematic map of the clinic space on patient interface  250  to show the patient how to walk to their next destination in the clinic. In another embodiment, the patient interface  250  can be configured to communicate directions verbally, such as by text-to-speech software. 
     In one embodiment, the encounter module  200  may be configured to monitor which rooms and devices in an office are “in use” based on information provided by the tracking system  240 . In one embodiment, the encounter module  200  may be configured to select a next location for a patient based on which rooms or devices  260  may be free to use. For example, if the encounter module  200  determines that a device  260  required for the next stage of a clinic process  205  is occupied or busy, the encounter module  200  can be configured to alter the clinic process  205  by inserting, for example, a waiting room order that, for example, can be removed from the clinic process  205  when the required device is free for use. 
     In one embodiment, the encounter module  200  can be configured to monitor utilization of a device  260  or clinic area that may be required for the next stage of a clinic process  205  and may be configured to insert an order for a patient to move to that device  260  or clinic area when it becomes free for use. 
     In another embodiment, the encounter module  200  can be configured to monitor the list of patients waiting for a provider and also to determine which providers have the shortest waiting lists or waiting times based on, for example, the number of patients in a waiting patient list and the average time the provider spends with each patient. The encounter module  200  can be configured to use this information, for example, to assign patients to providers with the shortest wait times so as to improve clinic flow. Numerous other embodiments of device decisions based on dynamic knowledge of device and space utilization within an office space are possible. 
     An example of a healthcare encounter is shown in  FIG. 11 . In one embodiment, the first step in the encounter may be registration  400  which can be completed, for example, by office staff or by the patient using, for example, an office interface  210 . Encounter registration  400  may be comprised of many steps such as signing the patient&#39;s name and address, presenting identification, verifying insurance status, paying co-payments due prior to the encounter, consenting to be seen by the provider, consent to privacy regulations or payment of other fees. In other embodiments, the user may skip registration  400  and may proceed to other steps, such as examination  410 . 
     In one embodiment, one step in an automated healthcare encounter can be verification of the user&#39;s identity. This may be accomplished, for example, as part of registration  400 , as part of examination  410 , prior to using any device  260 , or at other times in the encounter. A mobile patient interface  250  may be advantageous since it can verify the user&#39;s identity once and then communicate this identity to, for example, the encounter module  200 , to providers, or to subsequent devices used throughout the encounter, such as devices  260 . 
     In various embodiments, the patient interface  250  can be configured to verify the user&#39;s identity through biometrics, such as through recognition of the patient&#39;s face, voice, fingerprint or other unique physical aspects of the subject. In other embodiments, the patient interface  250  can be configured to verify the user&#39;s identity through confirmation of a user&#39;s unique data, such as their names, date of birth, addresses, mother&#39;s maiden name, or answers to questions only known to the user. In another embodiment, the patient interface  250  can be configured to verify the user&#39;s identity through confirmation of code, such as a password or secret code known only to the user. In still another embodiment, the patient interface  250  can be configured to verify the user&#39;s identity through coupling of a device carried only by the user, such as a key, electronic device, bar code or QR code. 
     In one embodiment of an electronic healthcare encounter, the user may complete the history portion of their examination as part of their overall encounter. As discussed previously, in various embodiments, the history portion of the encounter can be collected, for example, by office staff or by the patient themselves. Office staff may use the patient interface  250  or the office interface  210  to conduct or enter results from a patient history. In other embodiments, the patient may use the patient interface  250  to complete their own history without interacting with office staff. 
     In various embodiments, the questions can be configured in a form that facilitates responses using written, mouse-based, tablet-based or voice entry such as multiple choice, true or false, or pull-down menu selections. In other embodiments, the questions may require free entry such as by writing, voice dictation, or keyboard entry. In these examples, the patient interface  250 , the office interface  210  or the encounter module  200  may be configured to interpret electronic forms of these inputs, such as electronic writing or voice dictation. 
     In one embodiment, the history portion of the encounter may be comprised of a standard series of questions. In another embodiment, the series of questions may be based on, for example, a preference specified by the provider, the patient&#39;s diagnosis, the patient&#39;s symptoms or some other unique aspect of the encounter. 
     In still another embodiment, the history portion of the encounter can be comprised of questions from a database whereby the next question to be asked can be determined, for example, based on an answer to a previous question. This dynamically-traversed database of questions may use answers from a question to determine subsequent questions to ask or to determine sets of questions to ask based on a tree organization of questions in the database. For example, if a patient reports color vision loss, the system can be configured to add a series of questions related to color vision loss to its list of questions even if they were not previously included in the set of questions to be asked. In later questioning, it the patient reports pain on eye movement, the system can be configured to add, for example, questions related only to pain on eye movement or questions related to pain on eye movement and color vision loss. The dynamic allocation of new questions based on answers to previous questions can be configured such that a provider can allow or disallow such a feature. 
     In one embodiment, a dynamically-traversed electronic questionnaire can be configured to assign priority values to each question so that certain questions can be asked before other questions. In still another embodiment, the system can provide a running count of the total number of questions to be asked to the patient along with an estimated total time to completion. In related embodiments, the system can be configured to allow users or providers to shorten the questionnaire, such as by excluding lower priority questions, based on aspects of the dynamic questionnaire such as it taking too much time or involving too many questions and answers. 
     In another embodiment, the patient interface  250  can be configured to allow the user to change display parameters, such as size, color and font type, used to display questions with the patient interface  250 . In other embodiments, the patient interface  250  can be configured to read questions aloud, for example using a text-to-speech system or pre-recorded voices, or to ensure privacy by providing a headphone jack where the user can connect headphones. 
     In one embodiment, the encounter module  200  can be configured to direct devices  260  to perform tests and store results associated with the clinic process  205  and the patient&#39;s information contained within the encounter module  200 . The encounter module  200  can be configured to communicate with these devices  260  using a direct wired connection, such as a USB, Ethernet or serial connection, a wireless connection, such as Bluetooth® or 802.11, an intermediate electronic device, such as a USB key, memory card or patient interface  250 , or a physical coded embodiment such as a bar code or QR code. 
     In one embodiment, the encounter module  200  or patient interface  250  can be configured to alter the list of tests requested for an encounter based on answers to history questions or results from testing on devices  260 . The encounter module  200  or the patient interface  250  can also be configured to direct a device  260  to conduct a new test or tests in addition to or in place of the old test or tests. Alteration of the clinic process  205  by the encounter module  200  or patient interface  250  can be allowed or disallowed by a provider either globally or specifically, such as based on answers to specific questions or categories of questions, using, for example, the office interface  210 . 
     In one embodiment, the encounter module  200  or the patient interface  250  can be configured to initiate operation of a device  260 , such as an instrument to measure vision. In another embodiment, the encounter module  200  or the patient interface  250  can be configured to allow the user to initiate operation of a device  260 , such as by saying “ready”, pushing a button or pressing a pedal that may be attached to the patient interface  250 . In still another embodiment, the encounter module  200  or the patient interface can be configured to allow the user to initiate operation of the device  260 , such as by saying “ready”, pushing a button or pressing a pedal, through the device  260 . 
     As discussed previously, the encounter module  200  or the patient interface  250  can be configured to receive data, such as examination results, from devices, such as the tracking system  240 , the patient interface  250  or devices  260 . As discussed above, the encounter module  200  can be configured to communicate with these other components using, for example, a wired connection, a wireless connection, an intermediate electronic, or using a physical embodiment. 
     Collection of data from numerous devices by the patient interface  250  or encounter module  200  can be particularly advantageous by reducing transcription or sorting errors that can occur when human laborers are involved in these processes or by centralizing all encounter data in one location. 
     Various components in the electronic encounter system, such as the encounter module  200 , can be configured to compile encounter data into a digital package or packages that can be uploaded to, for example, an electronic health record system either in the office, such as the office database  220 , or outside the office via secure external communication  235 , transmitted to other individuals on a patient&#39;s healthcare team via secure external communication  235 , reviewed directly by the provider on a patient interface  250  or office interface  210 , or stored on an accessible external database  230 . The external database  230  can be configured to be accessible remotely, such as via the Internet, for example, to facilitate sharing of exam data between providers or to facilitate access by the patient to their own healthcare data. 
     As discussed previously, the encounter module  200  can be configured to track both patients and clinic personnel using the tracking system  240 . The encounter module  200  can be configured to store tracking information such that it, for example, can be viewed or analyzed using an office interface  210 . By tracking a patient&#39;s location over time, the encounter module  200  can be configured to develop clinic patient flow maps that may enable staff to identify both acute and chronic problems with clinic flow. For instance, identification of a patient by the encounter module  200  who has been waiting longer than a pre-defined threshold value stored in a clinic process  205  can alert the staff, for example via an office interface  210 , to address problems with that patient&#39;s encounter that might be leading to this delay. Identification of chronic bottlenecks and waiting points across numerous encounters can allow practices to optimize their workflow. 
     Providers can be tracked in several ways. In one embodiment, mobile office interfaces  210  can be configured with tracking systems  240  to identify the location and identity of providers carrying them. In another embodiment, the patient interface  250  can be configured to require providers to log in whenever they are consulting with a patient. In still another embodiment, the tracking system  240  can be configured to monitor the location or identity of providers wearing identifiers, such as RFID tags. In other embodiments, the encounter module  200  could be configured to communicate updates to patients, such as by using the patient interface  250 , to, for example, estimate the approximate wait times until the provider sees them or to convey how many patients still need to be seen by the provider before they are seen by the provider. 
     The electronic encounter portal can also be configured to provide entertainment or education to a patient. For example, the patient interface  250  can be configured to provide Internet access  235 , access to previous encounter records stored on the encounter module  200 , or access to previous encounter records stored on the external database  230 . The patient interface  250  can also be configured to provide access by the patient to educational resources, potentially targeted toward the diagnosis or future treatments for a patient, that may be stored on components such as the encounter module  200 . In one embodiment, the provider can use a patient interface  250  or an office interface  210  to enter orders for an educational program into a clinic process  205 . 
     In another embodiment, the patient interface  250  can be used to inform a patient about clinic resources, such as clinical trials, support programs, therapeutic services, restrooms, refreshments, etc. based on information stored on the encounter module  200 . The encounter module  200  can also be configured to direct patients to these resources, such as restrooms, based on information from the tracking system  240  and requests from the patients using the patient interface  250 . The encounter module  200  can also be configured to manage communications between patients, using a patient interface  250  and office staff, such as by using an office interface  210 . 
     In one embodiment, the patient interface  250  can be configured to store data from devices and, in an embodiment that is mobile such as a tablet or smartphone, can allow the patient to transport encounter data through the clinic process  205  for review by or with the provider. In another embodiment, the office interface  210  can be configured to enable data to be uploaded for review by the provider. Both the patient interface  250  and the office interface  210  can be configured to access and use prior visit data from the encounter module  200  to enhance assessments of a patient&#39;s healthcare status. Similarly, both the patient interface  250  and the office interface  210  can be configured to access prior data from the external database  230  to enhance assessments of a patient&#39;s healthcare status. 
     In related embodiments, the encounter module  200  and the external database  230  can be configured to act as common locations for encounter data that can be accessed by both patients and providers. The external database  230  can be configured to allow remote access to encounter data by both providers and patients when they are outside of the office. Similarly, the external database  230  can be configured to receive data from devices  260  at locations outside of the described office and share these results with the encounter module  200  for example, to enable automated remote healthcare encounters. 
     In one embodiment of an electronic encounter portal, a check-out procedure  420  may be the last order or step in a clinic process  205 . In various embodiments, the office interface  210  or the patient interface  250  can be configured to allow providers to enter orders for future encounters such as testing or therapies. In other embodiments, the office interface  210  can be configured to enable the provider to enter billing information to be submitted for insurance reimbursement or directly charged to the patient. In still another embodiment, the office interface  210  can be configured to allow the provider to recommend a follow-up interval for the next encounter. In a related embodiment, the office interface  210  or the patient interface  250  can be configured to allow the patient to select the best time and data for a follow-up encounter. In another embodiment, the office interface  210  can be configured to allow the provider to order educational materials or educational sessions for the patient that may occur after the encounter concludes. 
     Accordingly, various embodiments described herein can reduce the need for clinic personnel to perform these tasks. In addition, various embodiments enable users to conduct their own complete eye exams. 
     Automated Eye Examination 
       FIG. 12  shows an example of a binocular eye examination system based on optical coherence tomography. Component  500  may be comprised of the main electronics, processors, and logic circuits responsible for control, calculations, and decisions for this optical coherence tomography system. Light can be output from light source  502  which may be controlled at least in part by component  500 . The light source may be comprised of a broadband light source such as a superluminescent diode or tunable laser system. The center wavelength for light source  502  can be suitable for optical coherence tomography of the eye, such as 840 nm, 1060 nm, or 1310 nm. The light source  502  may be electronically controlled so that it can be turned on, off or variably attenuated at various frequencies, such as 1 Hz, 100 Hz, 1 kHz, 10 kHz or 100 kHz. In one embodiment, light from light source  502  can travel through interferometer  504 , which may be comprised of a Mach Zender or other type of interferometer, where a k-clock signal can be generated. This electronic signal can be transmitted to electronics on component  500  or other components in the system and can be captured on a data acquisition system or used as a trigger for data capture. 
     The k-clock signal can be used as a trigger signal for capturing data from balanced detectors  518   r  and  518   l . Alternatively, the k-clock signal can be captured as a data channel and processed into a signal suitable for OCT data capture. This k-clock signal can be captured all of the time, nearly all of the time or at discrete times after which it would be stored and recalled for use in OCT capture. In some embodiments, various parameters of the k-clock signal, such as frequency or voltage, can be modified electronically, such as doubled or quadrupled, to enable deeper imaging in eye tissues. In various embodiments with light sources that sweep in a substantially linear fashion, the k-clock can be removed and a regular trigger signal may be employed. In various embodiments, the trigger signals used by electronics  595   r  and  595   l  may be synchronized with other components of the system, such as mirrors, variable focus lenses, air pumps and valves, pressure sensors and flow sensors. 
     Most of the light, such as 90% or 95%, that enters the interferometer  504  can be transmitted through interferometer  504  to a beam splitter or coupler  510 . As used herein, “coupler” may include splitters as well as couplers. Beam coupler  510  can split the light from interferometer  504  or light source  502  to two output optical paths, specifically right and left, that lead directly to couplers  515   r  and  515   l . Henceforth, designation of a device or component with a suffix of ‘r′’ or ‘l’ will refer to two devices that may be of the same type but are located in different optical paths. For example, one component may be located in the optical path of the right eye, designated as ‘r,’ and the other is located in the optical path of the left eye, designated as ‘l.’ 
     The optical paths in this system may be comprised of fiber optics, free space optics, a mixture of free space and fiber optics. Other combinations are also possible. The split ratio of coupler  510  can be a predefined ratio, such as 50/50 or 70/30. Light from coupler  510  can travel to couplers  515   r  and  515   l . Couplers  515   r  and  515   l  may also split light from coupler  510  with a predefined split ratio such as a 50/50, 70/30, or 90/10. The split ratios for couplers  510 ,  515   r  and  515   l  may be the same or different split ratios. 
     One portion of light from couplers  515   r  and  515   l , such as 70%, can travel to a so-called ‘reference arm’ for each of the right and left optical paths. The reference arm of a light path is distinguished from the so-called sample arm of the light path since light in the reference arm of the system does not interface with eye tissue directly whereas light in the sample arm is intended to contact eye tissue directly. 
     The main component in the reference arm may be an optical delay device, labeled as  516   r  and  516   l  in the right and left optical paths of the system. Optical delay devices can introduce a delay, such as 1 picosecond, 10 picoseconds or 100 picoseconds, into a light path to enable matching of the overall path length of one optical path to the optical path length of another light path. In various embodiments, this optical delay may be adjustable, such as with an adjustable free light path between two collimating optical devices, a fiber stretcher that increases or decreases the length of a fiber optic, or a fiber Bragg grating that delays light based on changes in the angle of incidence of light. 
     In other embodiments, this optical delay line can include variable attenuators to decrease or increase the transmission of light, optical switches or mechanical shutters to turn the light off or on. Although pictured in the reference arm of this system, an optical delay line can also be entirely included in the sample arm optical path for each eye or contained in both the reference and sample arm light paths. Other combinations of sample and reference light paths are also possible. 
     In one embodiment, light from optical delay devices  516   r  and  516   l  can travel to couplers  517   r  and  517   l  where it may be combined with light from the sample arm that has been transmitted from couplers  515   r  and  515   l . Couplers  517   r  and  517   l  may combine light from two light paths with a predefined ratio between paths such as a 50/50, 70/30, or 90/10. Light from couplers  517   r  and  517   l  may travel through two outputs from couplers  517   r  and  517   l  to balanced detectors  518   r  and  518   l  where the light signal can be transformed into an electrical signal, for example through the use of photodiodes configured to detect the light input from couplers  517   r  and  517   l.    
     The electrical signal generated by balanced detectors  518   r  and  518   l  can be in various ranges, including but not limited to −400 mV to +400 mV, −1V to +1V, −4V to +4V and have various bandwidths, including but not limited to 70 MHz, 250 MHz, 1.5 GHz. The electrical signal from balanced detectors  518   r  and  518   l  may travel via an electrical connection, such as a coaxial cable, to electronics  595   r  and  595   l  where it can be captured by a data acquisition system configured to capture data from balanced detector devices. Although not pictured here, a polarization sensitive optical component can be disposed before balanced detectors  518   r  and  518   l  to split two polarities of light in a single light path into two optical paths. In this embodiment, two optical paths leading to balanced detectors  517   r  and  517   l  would be split into a total of four optical paths which would lead to two balanced detectors on each side. 
     One portion of light from couplers  515   r  and  515   l , such as 30% or 50%, can travel to a so-called sample arm of each of the right and left optical paths. In various embodiments, the system may be configured to transmit the light through fiber optic cable or through free space optics. Light from couplers  515   r  and  515   l  can travel to optics  520   r  and  520   l  which may be collimators configured to collimate the light from couplers  515   r  and  515   l . Light from optics  520   r  and  520   l  can travel to lens systems  525   r  and  525   l  which may be comprised of fixed focus or variable focus lenses. 
     In various embodiments, these lenses can be fabricated from plastic or glass. In other embodiments, these lenses may be electrowetting lenses or shape-changing lenses, such as fluid-filled lenses, that can vary their focal distance based on internal or external control mechanisms. In one embodiment, variable focus lenses in lens systems  525   r  or  525   l  may have their focal length modified by electrical current or voltage applied to lens systems  525   r  or  525   l . This control may come from electrical components  595   r  and  595   l  and the parameters of this control may be based on pre-determined values or may be derived during operation of the system based on input received from other components of the system. 
     The lenses in lens systems  525   r  and  525   l  can be configured to have anti-reflective coatings, embedded temperature sensors, or other associated circuitry. Lens systems  525   r  and  525   l  may be comprised of a single lens or multiple lenses. The lenses comprising systems  525   r  and  525   l  may be present at all times or may be mechanically moved in and out of the light path such as by an attached motor and drive circuit under electrical control from components  595   r  and  595   l . Configuration of lens systems  525   r  and  525   l  to be moveable can enable imaging at different depths in an eye tissue by introducing and removing vergence in the optical system. 
     Light from lens systems  525   r  and  525   l  can travel to movable mirrors  530   r  and  530   l . Movable mirrors  530   r  and  530   l  may be comprised of MEMS (microelectromechanical systems) mirrors, controlled by galvanometers, or moved by other means. Movable mirrors  530   r  and  530   l  can be comprised of a single mirror that reflects light across 2 axes, such as X and Y, can be comprised of a single mirror that reflects light across one axis only, or can be comprised of two mirrors that each reflect light across one axis only said axes being substantially perpendicular to each other. 
     Electrical control of mirrors  530   r  and  530   l , which may control each axis of reflection independently, can be provided by components  595   r  and  595   l . The electronic control of mirrors  530   r  and  530   l  may be configured to enable variable amplitude deflections of mirrors  530   r  and  530   l . For example, for a given drive frequency in a given axis, the current or voltage applied to mirrors  530   r  and  530   l  may enable larger or smaller amplitude deflections of the mirror surface, thus creating a zoom effect where the created image can be made smaller or larger. 
     Light that has been reflected from movable mirrors  530   r  and  530   l  can travel to lens systems  535   r  and  535   l . Lens systems  535   r  and  535   l  may be fixed or variable focus lenses that are located in the optical light path at all times or only part of the time. Electrical control of lenses  535   r  and  535   l , can be conducted by components  595   r  and  595   l  and may include for example moving these lenses in and out of the light path or changing their focal lengths. Other actions are also possible. 
     Light from lens systems  535   r  and  535   l  can travel to optics  540   r  and  540   l  which may be comprised of dichroic mirrors or couplers. Optics  540   r  and  540   l  may be configured to transmit light from lens systems  535   r  and  535   l  and combine it with light from lens systems  545   r  and  545   l . Light from optics  540   r  and  540   l  can travel to eye pieces  542   r  and  542   l  before being transmitted to the right and left eye tissues. 
     Eye pieces (or oculars)  542   r  and  542   l  can be configured as multi-element lens systems such as Ploessel-type eyepieces, Erfle-type eyepieces, telescopes or other designs. In some embodiments, optics  540   r  and  540   l  may be configured to be part of or inside of eyepieces  542   r  and  542   l . In other embodiments, variable focus lenses or polarization-sensitive optics and beam splitters can be configured inside eyepieces  542   r  and  542   l  to enable wider axial focusing ranges in eye tissues or simultaneous focusing of light from two axial locations in eye tissues. Eyepieces  542   r  and  542   l  may be configured with optical components without any refractive power, such as optical windows, that may be physically attached or separate from the other lenses in the system. 
     Light entering the right and left eyes can be reflected back through each optical path to enable optical coherence tomography. In one embodiment, the path of backreflected light originating from light source  502  can travel from each eye to eyepiece  542  to optics  540  to lens system  535  to movable mirror  530  to lens system  525  to optics  520  to coupler  515  to coupler  517  to balanced detector  518 . Various calculations and logic-based processes can be completed by components  595   r  and  595   l  based on data contained in signals received from balanced detectors  518   r  and  518   l.    
     As discussed previously, timing of capture of the signals received by components  595   r  and  595   l  may be controlled by other inputs, such as the k-clock input, dummy clock input, or other electrical signal. Electronics  500 ,  595   r , and  595   l  may be configured to have digital signal processors (DSPs), field-programmable gate arrays (FPGAs), ASICs or other electronics to enable faster, more efficient or substantially real-time processing of signals received by components  595   r  and  595   l . Electronics  500 ,  595   r , and  595   l  may be configured with software, such as a real-time operating system, to enable rapid decisions to be made by said components. 
     In various embodiments not illustrated here, the eye tissues may be replaced by calibration targets that, for example, occlude the eyepieces, dispose a mirror target at various distances in front of the eyepieces, or provide an open air space for calibration. Electronics  500  may be configured to control the introduction of these non-tissue targets, such as when the eyes are not present in the optical system. In other embodiments, electronics  500  may be configured to dispose powered or moveable components of the system to various states, such as “off,” “home,” or “safety” at various times, such as the beginning, middle and end of a test. 
     Components  595   r  and  595   l  can also be configured to control light sources  585   r - 588   r  and  585   l - 588   l  which may be comprised of various light sources such as for example, laser diodes, light emitting diodes, or superluminescent diodes. In the illustrated embodiment, only four light sources  585   r - 588   r  and  585   l - 588   l  are shown. In various embodiments, different numbers of light sources  585   r - 588   r  and  585   l - 588   l  may be used and different wavelengths of light sources may be used. In one embodiment, one each of a blue-colored, green-colored, red-colored and near infrared diode can be included in the light source groups  585   r - 588   r  and  585   l - 588   l.    
     In other embodiments, light sources  585   r - 588   r  and  585   l - 588   l  may be comprised of tunable light sources capable of producing numerous spectra of light for the purposes of hyperspectral imaging. For example, employing various light sources in the visible spectrum capable of producing narrow bands of light centered at characteristic peaks of absorption or reflectivity for oxyhemoglobin and deoxyhemoglobin can be used to enable hyperspectral imaging. Similarly, numerous individual light sources can be used to achieve the same effect as a light source with a tunable wavelength. 
     These light sources can be configured to be controlled by components  595   r  and  595   l  using, for example, pulse-width modulation, current modulation, voltage modulation, or other electrical control means. In one embodiment, the modulation frequency of at least one light source can be modified to correct for chromatic aberration from the optics between the light sources and the eye. For example, the modulation frequency of the red channel could be variably increased or decreased in different mirror positions to account for lateral chromatic spread between the red light source and other colors such as blue or green. 
     Light from light sources  585   r - 588   r  and  585   l - 588   l  can travel to optics  580   r - 583   r  and  580   l - 583   l  which may, for example, be focusing optics. Light from optics  580   r - 583   r  and  580   l - 583   l  can then travel to optics  575   r - 578   r  and  575   l - 578   l  which may, for example, be focusing optics. Each path of light can contain a single frequency of light, such as 450 nm, 515 nm, 532 nm, 630 nm, 840 nm, or 930 nm or multiple frequencies of light. 
     Each path of light from light sources  585   r - 588   r  and  585   l - 588   l  may be reflected off optics  571   r - 574   r  and  571   l - 574   l  which may, for example, be dichroic mirrors or couplers and may be specifically configured to reflect and transmit light based on their position in the optical path. For example, one optic may be configured to transmit light with a wavelength less than 500 nm and reflect light with a wavelength greater than 500 nm. 
     Optics  571   r - 574   r  and  571   l - 574   l  can be configured to join together light from different light sources  585   r - 588   r  and  585   l - 588   l  into a single, substantially coaxial beam of light that can travel to optics  561   r  and  561   l . Optics  561   r  and  561   l  may be dichroic mirrors or couplers and may be configured to have a pre-defined split ratio of light entering from different directions or having different wavelengths, such as 90/10, 50/50, and 10/90. 
     A portion of light from optics  571   r - 574   r  and  571   l - 574   l  can be transmitted through optics  561   r  and  561   l  to sensors  566   r  and  566   l  which may, for example, be photodiodes or other components capable of sensing light. Signals from sensors  566   r  and  566   l  can be configured to be transmitted along electrical connections between sensor  566   r  and electrical component  595   r  on the right side and sensor  566   l  and electrical component  595   l  on the left side. In one embodiment, sensors  566   r  and  566   l  can be configured to monitor the total light power being emitted by light sources  585   r - 588   r  and  585   l - 588   l.    
     The portion of light reflected off optics  561   r  and  561   l  from optics  571   r - 574  and  571   l - 574   l  can travel to lens systems  560   r  and  560   l . Lens systems  560   r  and  560   l  may be comprised of fixed focus or variable focus lenses. In various embodiments, these lenses can be fabricated from plastic or glass. In other embodiments, these lenses may be electrowetting lenses or shape-changing lenses, such as fluid-filled lenses, that may vary their focal distance based on internal or external control mechanisms. 
     In one embodiment, variable focus lenses in lens systems  560   r  and  560   l  may have their focal length modified by electrical current or voltage applied to the lens systems. This control may be under the direction of electrical components  595   r  and  595   l  and it may be based on pre-determined values or be derived during operation of the system based on input received from other components of the system. 
     The lenses in lens systems  560   r  and  560   l  can be configured to have anti-reflective coatings, embedded temperature sensors, or other associated circuitry. Lens systems  560   r  and  560   l  may be comprised of a single lens or multiple lenses. The lenses comprising systems  560   r  and  560   l  may be present in the light path at all times or may be mechanically moved in and out of the light path by an attached motor and drive circuit under electrical control from components  595   r  and  595   l . Configuration of lens systems  560   r  and  560  to be moveable can enable imaging at different depths in an eye tissue by introducing and removing vergence in the optical system. 
     Light from lens systems  560   r  and  560   l  can travel to lens systems  555   r  and  555   l . In some embodiments, lens systems  555   r  and  555   l  can be located in their respective optical paths at all times. In other embodiments, lens systems  555   r  and  551  may be moved in and out of the optical paths based on electrical signals from components  595   r  and  595   l.    
     Light from lens systems  555   r  and  555   l  can travel to movable mirrors  550   r  and  550   l . Movable mirrors  550   r  and  550   l  may be comprised of MEMS mirrors, controlled by galvanometers, or moved by other means. Movable mirrors  550   r  and  550   l  can be comprised of a single mirror that reflects light across 2 axes, such as X and Y, can be comprised of a single mirror that reflects light across one axis only, or can be comprised of two mirrors that each reflect light across one axis only said axes being substantially perpendicular to each other. 
     Electrical control of mirrors  550   r  and  550   l , which can control each axis of reflection independently, can be provided by components  595   r  and  595   l . Mirrors  550   r  and  550   l  may have one axis of fast resonant movement, one axis of slow resonant movement, two slow axes of movement, one fast resonant axis and one slow axis of movement, or two fast resonant axes of movement. 
     The electronic control of mirrors  530   r  and  530   l  may be configured to enable variable amplitude deflections of mirrors  530   r  and  530   l . For example, for a given drive frequency in a given axis, the current or voltage applied to mirrors  530   r  and  530   l  may enable larger or smaller amplitude deflections of the mirror surface, thus creating a zoom effect where the created image can be made smaller or larger. 
     Light from movable mirrors  550   r  and  550   l  can travel to lens systems  545   r  and  545   l . Lens systems  545   r  and  545   l  may be configured to introduce variable amounts of optical cylinder power into the optical light paths. In one embodiment, the magnitude and axis of the cylindrical optical power introduced into the optical paths by lens systems  545   r  and  545   l  can be configured to correct an astigmatism present in an eye interfacing with this system. 
     Lens systems  545   r  and  545   l  can comprised of two cylindrical lenses configured to counter-rotate and co-rotate with each other, an electrically controlled variable focus, liquid filled lens, or other method of introducing cylindrical optical power into a light path. Although not illustrated here, lens systems  545   r  and  545   l  can also be located between mirrors  530   r  and  530   l  and optics  540   r  and  540   l  in the OCT light path. 
     Light from lens systems  545   r  and  545   l  can travel to optics  540   r  and  540   l  where it may be reflected to combine with light originating at light source  502 . In one embodiment, an exit pupil expander can be disposed between moveable mirrors  550   r  and  550   l  and the eye tissues to increase the size of the exit pupil created at the eye tissue by mirrors  550   r  and  550   l.    
     Light from lens systems  545   r  and  545   l  may be transmitted through eyepieces  542   r  and  542   l  after which it may enter the right and left eyes of a subject. Light transmitted through eyepieces  542   r  and  542   l  can be configured to be seen by the subject as organized light, such as in a retinal scanning display system, can be configured to be seen by the subject as video-rate imaging through modulation of light sources  585   r - 588   r  and  585   l - 588   l  by components  595   r  and  595   l , or can be configured to broadly stimulate the eye with light such as for measurements of pupillary reactions to light stimuli. 
     Light from lens systems  545   r  and  545   l  can also be configured to reflect back out of the eye and through eyepieces  542   r  and  542   l , off optics  540   r  and  540   l , through lenses systems  545   r  and  545   l , off moveable mirrors  550   r  and  550   l , through lens systems  555   r ,  555   l ,  560   r , and  560   l  and then through optics  561   r  and  561   l . Light transmitted through optics  561   r  and  561   l  can be detected by sensors  567   r - 570   r  and  567   l - 570   l  which may, for example, be comprised of photodiodes. 
     In various embodiments, this light is split into predefined wavelength bands, such as 440 nm-460 nm, 510 nm-580 nm, 625 nm-635 nm, or 930 nm, by dichroic mirrors  562   r - 565   r  and  562   l - 565   l . In other embodiments, separation of light from optics  561   r  and  561   l  into bands can be achieved by the use of filters that selectively transmit or reflect wavelength bands of interest. 
     In still other embodiments, separation of light from optics  561   r  and  561   l  into bands can be achieved by configuring the system with sensors  567   r - 570   r  and  567   l - 570   l  that only produce electrical signals in specifically targeted bands, such as 400-500 nm, 600-800 nm or &gt;900 nm. Electrical signals from sensors  567   r - 570   r  and  567   l - 570   l  can travel to components  595   r  and  595   l  across electrical connections to enable imaging of tissues in the eye by sensing the light originating at light sources  585   r - 588   r  and  585   l - 588   l  backreflected in desired wavelength bands. 
       FIG. 13  shows an example of a display of eye examination data on an electronic device  600 . In some embodiments, the display system enables viewing and comparing of data from two eyes of one patient across multiple tests and dates in a minimal amount of space. Accordingly, some embodiments enable the user to collapse undesirable test or date fields so as to maximize the display area of desired measurements. 
     Device  600  may be a portable computing platform, such as a smartphone or a tablet, or be a stationary computing platform with a display screen. Device  600  may allow touch screen operation, eye tracking operation where eye movements are interpreted as cursor movements on the device  600  itself or operation with standard computing peripherals such as a mouse and keyboard. 
     Data in the illustrated grid can be populated by software from a database of examination data that may, for example, include exams from many patients on many days. Accordingly, software running on device  600  can be configured to enable searching or selection of the patient whose exam data is to be displayed in the illustrated display configuration. 
     Software on device  600  can be configured to output exam data in a substantially tabular format comprised mainly of rows  612  and columns  614 . In various embodiments, the software can be configured to include all exam data for a given date in one column  614  while all measurements from a given test can be included in a single row  612 . The software can also enable preferences that allow transformation of this rule such that dates are in rows  612  and tests are in columns  614 . In some embodiments, each box in the table representing an intersection of a row  612  and a column  614  can be represented as a field populated with, for example, a numerical measurement, a text value or an image. Although the fields are labeled generically in  FIG. 6 , it will be appreciated that a variety of data, such as numbers, text or images, can be displayed in each field. 
     Field  610  can be configured to contain information on the patient, such as name, date of birth, medical record number, age, gender. Although not illustrated here, field  610  may also be used to open pop-up windows that can be used to search or configure the exam display system. 
     Fields  620 - 625  can be configured to contain dates of exams for a given patient. In one embodiment, clicking of a column heading  620 - 625  toggles the column between collapsed and expanded configurations where data is not displayed in the collapsed configuration but data is displayed in the expanded configuration. In  FIG. 6 , columns  620 ,  623  and  625  demonstrate expanded fields while columns  621 ,  622  and  624  represent collapsed fields. Thus, the fields in the collapsed columns  621 ,  622 ,  624  may be collapsed. For example, fields  650 ,  651 ,  652 ,  653 ,  654  may be collapsed when column  621  is collapsed. The software can be configured to allow users to toggle this display setting with, for example, a simple click of a column heading or other selection process. 
     Fields  630 - 634  can be configured to contain individual tests conducted on a given patient. In one embodiment, clicking of a row heading  630 - 634  toggles the row between collapsed and expanded configurations where data is not displayed in the collapsed configuration but data is displayed in the expanded configuration. In  FIG. 6 , rows  63  land  634  demonstrate expanded fields while rows  630 ,  632  and  633  represent collapsed fields. Thus, the fields in the collapsed rows  630 ,  632 ,  633  may be collapsed. For example, fields  640 ,  650 ,  660 ,  670 ,  680 , and  690  may be collapsed when row  630  is collapsed. The software can be configured to allow users to toggle this display setting with, for example, a simple click of a row heading or other selection process. 
     In  FIG. 13 , it can be appreciated that two special rows can exist corresponding to the right (OD) and left (OS) eye headings. The software can be configured to collapse or expand all tests for a given eye when that row heading, such as OD or OS, is clicked or otherwise selected. 
     Referring to  FIG. 13 , fields  641 ,  644 ,  671 ,  674 ,  691 , and  694  can be configured to display data, such as numbers, text or images. In one embodiment, display of images in these fields enables the user to click on the images to bring up a larger window in which to view the images. In another embodiment, display of numbers in these fields enables the user to click on the numbers to bring up a graph of the numbers, such as graph over time with the dates in the column headers as the x-axis and the values in the rows as the y values. 
     The software can be configured to show collapsed fields (e.g. field  640 ,  650 ,  660 ,  651 ,  661 ) in a different color or in a different size. The software can also be configured to display scroll bars when fields extend off the display screen. For example, if more tests exist in the vertical direction than can be displayed on a single screen, the software can be configured to allow panning with finger movements or scrolling with, for example, vertical scroll bars. The software can be configured to enable similar capabilities in the horizontal direction as well. 
     As described above, in some embodiments, a mask  100  is configured to be interfaced with an ophthalmic device for performing an eye exam on a patient. In some embodiments, the ophthalmic device comprises an optical coherence tomography (OCT) device such as described above. An OCT device is operable to direct an incident light beam onto a patient&#39;s eye and receive a reflected or scattered light beam from the patient&#39;s retina. Three-dimensional images of eye tissue, such as the cornea, iris, lens, vitreous or retina may be obtained by measuring reflected or scattered light from the tissue for example using Optical Coherence Tomography or other instruments. Many OCT devices employ beam-steering mirrors, such as mirror galvanometers or MEMS mirrors, to direct the light beam to an object of interest. Various OCT instruments comprise interferometers including light sources and optical detectors or sensors that receive light reflected or scattered from the eye and produce a signal useful for imaging the eye. One example of an OCT device is described above with reference to  FIG. 12 . 
     When the mask  100  is interfaced with an OCT device for performing an eye exam, an incident light beam is transmitted through at least one of the optically transparent sections  124  of the mask  100  before impinging on the retina of the eye. A portion of the incident light beam may be reflected by the optically transparent sections  124  of the mask. Such reflection is undesirable as it decreases the amount of light transmitted to the retina of the eye and the reflected portion of the incident light beam may also reach the OCT device (e.g., the optical detector  518  therein) and may obscure the signal of interest, namely the reflected or scattered light from the retina. In some embodiments, to ameliorate this problem, the optically transparent sections  124  of the mask  100  are coated with an anti-reflective coating configured to reduce reflection of the incident light beam by the optically transparent sections  124 . In various embodiments, the optical transparent sections  124  of the mask are configured to increase or maximize transmission of light, such as from an OCT device, and the proximal portions  154  and concaved rear surface  122  is configured to reduce or minimize transmission of light, such as ambient light or light not emanating from an OCT machine and may be opaque and include opaque sides. For example, the proximal portions  154  may have sides that are substantially non-transmissive to visible wavelengths. These sides may for example block 80-90%, 90-95%, 95-99%, and/or 99-100% of ambient visible light. Reduction of ambient light may for example assist in keeping the patients pupils dilated. Conversely, the optically transparent sections may have a transmittance of 70-80%, 80-90%, 90-95%, 95-99%, and/or 99-99.5%, or 99.5%-100% or any combination of these ranges in the wavelength range at which the ophthalmic device operates such as at 450 nm, 515 nm, 532 nm, 630 nm, 840 nm, 930 nm, 1060 nm, 1310 nm or any combination thereof or across the visible wavelength range, near IR wavelength range, or both these ranges or at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of the visible range, near IR range, or both. In some embodiments, material (treated or untreated) such as plastic that is not substantially transparent to visible light or to many visible wavelengths but is transparent to infrared light may be employed, for example, as the window to the mask and possibly for at least part of the proximal portion (e.g., the sides). The window would thus potentially be able to transmit an IR probe beam from the ophthalmic device (e.g., OCT or SLO instrument) yet could block ambient visible light or a significant portion thereof thereby allowing the user&#39;s pupils when wearing the mask to be more dilated. In various embodiments, however, having a window having at least some wavelengths in the visible be transmitted through is useful for the wearer. In certain embodiments, the ophthalmic device operates at one or more near infrared wavelength. For example, the probe beam is in the near infrared. The window may therefore be transparent in at least at the NIR wavelength(s) at which the ophthalmic device operate, for example, at the probe wavelength. Optical coatings may be employed to impart these spectral characteristics on the mask (e.g., on the window). 
     In some embodiments, the anti-reflective coating is configured to reduce reflection of the incident light beam in a wavelength range that is comparable to the wavelength range of the light source used in the OCT device. For example, wide-spectrum sources such as superluminescent diodes, ultrashort pulsed lasers, swept source lasers, very short external cavity lasers, vertical cavity surface emitting lasers, and supercontinuum lasers can be used in OCT devices and could be used in other ophthalmic diagnostic and/or treatment devices. These light sources may operate in the visible and/or near infrared. For example, light sources that emit light in visible wavelengths such as blue, green, red, near infrared or 400-1500 nm may be used to image the eye. Accordingly, in some embodiments, the anti-reflective coating is configured to reduce reflection of the incident light beam in a wavelength range that is comparable to a visible spectrum. In some embodiments, the anti-reflective coating spans both a visible and invisible wavelength spectrum, operating at wavelengths such as 400 nm to 1500 nm, 450 nm to 1150 nm, 515 nm to 1100 nm or other regions. The anti-reflective coating may be strongly wavelength dependent or may be largely wavelength independent. Likewise, the anti-reflective coating may reduce reflection over a wide or narrow band. In some embodiments, the anti-reflective coating is configured to reduce reflection of the incident light beam in a wavelength band having a bandwidth ranging from about 5 nm to about 200 nm. In some embodiments, for example, this bandwidth may be between about 5 and 50 nm, 50 and 100 nm, 100 and 150 nm, 150 and 200 nm, 200 and 250 nm or larger. In some embodiments, the AR coating may operate across multiple bands that are separated from each other. Each of these bands may, for example, have a bandwidth, for example, as described above. The antireflective coating may reduce reflections at a normal incident angle to between about 5-10%, 3-5%, 1-3% or less. For example, with the anti-reflective coating, reflections at a normal incident angle may be reduced to 1 to 2% reflection, 0.5% to 1% reflection or 0.1% to 0.5% reflection, or 0.05% to 0.5% reflection, or 0.1% to 0.5% reflection, 0.1% to 0.01% reflection, or combinations thereof. In some embodiments, the amount of reflection may be higher or lower. In various embodiments, the anti-reflective coating operates on light from normal incidence up to oblique angles of incidence such as ±15 degrees, ±30 degrees or ±45 degrees. 
     The anti-reflective coating may comprise a multi-stack optical structure and, in particular, may comprise an interference coating such as a quarter-wave stack. The anti-reflective coating may comprise, for example, one or more layers having a thickness of a quarter or half wavelength of the light and accomplish reflection reduction through destructive interference. Other types of anti-reflection coatings may be employed. 
       FIGS. 14A-14D  a mask  200  for performing an eye exam according to an embodiment. The mask  200  includes a distal sheet member (distal portion)  218  and a proximal member (proximal portion)  254  coupled to the distal portion  218 . The distal portion  218  has one or more substantially optically transparent sections  224 . The proximal portion  254  has a rear surface  222  that faces the patient&#39;s face when in use, and is configured to conform to contours of the patient&#39;s face and align the one or more substantially optically transparent sections  224  of the distal portion  218  with the patient&#39;s eyes. The distal portion  218  can be configured to be optically interfaced with a docking portion of an ophthalmic device such as an OCT instrument. The ophthalmic device is operable to direct an incident light beam such as a probe beam onto and/or into a patient&#39;s eye and receive a reflected or scattered light beam from the patient&#39;s eye. The docking portion of the ophthalmic device includes an optical interface such an optically transparent window or plate for transmitting the incident light beam therethrough and incident on the optically transparent sections  224  of the distal portion  218 . The docking portion may also include a slot in which a flange on the mask fits into. In some embodiments, the ophthalmic device comprises an optical coherence tomography device although the ophthalmic device may comprise other diagnostic instruments or devices such as a scanning laser ophthalmoscope (SLO). 
     In some embodiments, to reduce retro-reflection back into the ophthalmic device, at least one of the optically transparent sections  224  of the mask has at least a portion thereof that is tilted or sloped with respect to the incident light beam when the distal sheet member  218  is optically interfaced with the docking portion of the ophthalmic device. In such embodiments the incident light beam forms a finite (non-zero) angle of incidence with respect to the corresponding portion of the mask. If the finite angle of incidence is sufficiently large, a retro-reflected light beam may be prevented from being retro-reflected back into the oculars of the ophthalmic device. In some embodiments, the magnitude of the tilt or slope angle is in a range from about 1 degree to about 30 degrees. In some embodiments, the magnitude of the tilt or slope angle is greater than about 1 degrees, 2 degrees, 4 degrees, 5 degrees, 6 degrees, 8 degrees, 10 degrees, 15 degrees, 20 degrees, 25 degrees, 30 degrees, 35 degrees, 40 degrees, 45 degrees, 50 degrees, or 55 degrees, and less than 60 degrees, 55 degrees, 50 degrees, 45 degrees, 40 degrees, 35 degrees, 30 degrees, 25 degrees, 20 degrees, 15 degrees, 10 degrees, or 5 degrees or any combination thereof. For example, the magnitude of the slope may be greater in magnitude than 30° and less than 35° or greater than 1° in certain portions and less than 35° or 40°. This tilt or slope angle may be measured between a central axis through the optical path from the ophthalmic device (e.g., OCT instrument) to the mask and the normal to the surface of the optically transparent section  224  of the mask where that central axis or probe beam is incident. In some embodiments, this angle may be measured, for example, with respect to the optical path from the ophthalmic device (e.g., OCT or SLO instrument) or optical axis of the ophthalmic devices, for example, from the exit pupil of left or right channel of the OCT or SLO instrument, an optical axis of an optical element (e.g., left and/or right ocular lens, eyepiece, or channel) associated with an ophthalmic device through which the beam passes prior to output from the ophthalmic devices, as well as from a normal to a transparent interface (e.g., a window or ocular lens) on the ophthalmic device. Also this angle may be measured with respect to the normal to the surface on the optically transparent section  224  of the mask where the beam or center thereof or central axis therethrough from the ophthalmic instrument would be incident on the optically transparent section  224 . Similarly, this angle may be measured with respect to the mask&#39;s forward line of sight when worn or the line of sight of a wearer of the mask. A standard anatomical headform such as an Alderson headform may be used to determine the line-of-sight through the mask. Accordingly, the angular ranges described above may be measured between the line-of-sight of a Alderson headform when the mask is placed on the headform as would be worn by a wearer (in the as worn position) and the normal to the surface of the optically transparent section  224  of the mask at the location that the normal line-of-sight of the headform intersects or passes. Other approaches to measuring the angle may also be used. 
     In various embodiments, the shape of the rear surface  222  is determined from measurements taken from at least one magnetic resonance imaging (MRI) scan of a human head. Segmentation of the surface of one or more faces (e.g., at least 10, 20, 30, 100, to 200, 500, 1000, or more faces) obtained from MRI images can be used to determine a contour that is substantially conformed to by the rear surface  222 . Statistical processes can be applied to these sets of MRI images to produce average face contours, median face contours, or face contours that match a certain percentage of the population, such as 95%, 99%, or 99.5%. These MRI images can also be used to define the line-of-sight through the mask. Standard lines defined by MRI images of the human head, such as the eye-ear line extending from the center of the ear canal to the lateral canthus where the eyelids join or a line in the Frankfurt plane extending from the center of the ear to the lowest portion of the eye socket, can be used to define the direction of the line-of-sight through the mask with a rear surface  222  defined by these same MRI images. Other lines, such as a line that connects the pupillary center and macular center as seen by MRI could also be used. The placement of the line-of-sight on the optical transparent section  224  may also be defined by measuring the distance between the pupils, the interpupillary distance (IPD), on the MRI images. 
     In various embodiments, the probe beam raster scanned across the tissue to obtain OCT signals over a region of the eye. As described above, to accomplish such raster scanning, the direction of the probe beam may be swept using, for example, a MEMS mirror.  FIG. 15A  illustrate an arrangement where a probe beam is reflected off a beam steering mirror through the mask window into the eye. The beam steering mirror can be rotate back an forth to sweep the beam through a range of angles and through a range of positions in and/or on the tissue being images or evaluated.  FIG. 15A  show both the optical path of the probe beam as well for light scattered from the tissue that returns back through the OCT instrument. As discussed above, in some instances, reflections from the mask window are retro-reflected and thus also return to the sensors used in the OCT instrument. With the normal to the window oriented at 0° with respect to the incident probe beam, light is reflected from the window back into the OCT instrument as shown in  FIG. 15A . This retro-reflected light introduces noise into the signal comprising scatters light from the tissue which could be a weak signal. The back reflection thus decreases the signal to noise ratio and makes obtaining an image more difficult. 
     To improve the signal to noise ratio, the window can be tilted an angle with respect to the beam. This tilt angle may be β degrees. The result is that the retro-reflected beam will be tilted such that the beam cannot enter back into the OCT instrument disrupting the signal. As illustrated in  FIG. 15B , for a given ophthalmic instrument such as an OCT instrument, there is an angle, Δ, of the retro-reflected beam (measured with respect to the incident beam or the incident optical path) at which the reflected beam is unlikely to enter back into the OCT instrument and introduce noise onto the OCT signal. This angle Δ may depend in part on the beam size, the size of the optics in the OCT instrument, e.g., the beam steering mirror, as well as the relative location of the optics longitudinally along the optical path. This angle may be for example, 0.5° to 1°, 1° to 2°, 2° to 3°, or combinations thereof. 
     In various embodiments, as illustrated in  FIG. 15C , the optics in the ophthalmic instrument are configured such that rays of light from the probe beam exiting the exit pupil or ocular of the ophthalmic instrument are generally converging. For example, the probe beam may substantially fill the exit pupil of the ophthalmic instrument and be focused down. Such approach may be referred to as a flood illumination. Also, as described above, in some embodiments, a beam having a beamwidth narrower than the aperture of the ocular or exit pupil of the ophthalmic instrument is swept through a range of angles. This approach may be referred to as beam steering. In both cases light rays may be incident on the mask at a range of angles, for example, defined by a cone angle (α). This range of angles may be determined, for example, by the F-number or numerical aperture of the output of ophthalmic device such as the ocular lens or focusing lens of the ophthalmic device and/or by the movable mirror (MEMS mirror). This range of angles may also correspond to the range of angles that the ophthalmic device will collect light. For example, rays of light reflected back into this range of angles, may be collected by the ophthalmic instrument and contribute to the signal received. This collection angle may also be determined by the F-number or numerical aperture of the ocular of the ophthalmic device (e.g., OCT instrument). 
     In some embodiments, the tilt or slope angle of the optically transparent section  224  of the mask is configured to be greater than the largest angle of incident light produced by the OCT or other imaging or ophthalmic device. For example, if an accompanying ophthalmic (e.g., OCT) device, because of beam steering or flood illumination, produces light rays between −30 degrees and +30 degrees with respect to the optical axis of the ophthalmic device or with respect to the central axis of the optical path from the ophthalmic device to the mask (e.g., a cone angle α of 30°), the magnitude of the tilt or slope angle (β) of the optically transparent section  224  of the mask can in various embodiments be greater than the cone angle, for example, more negative than −30 degrees or more positive than +30 degrees. For example, the tilt or slope angle, β, may be less than −30° (e.g., −31°, −32° etc.) or greater than +30° (e.g., 31° or more). 
       FIGS. 15C-15E  show how tilting the optically transparent section  224  reduces the likelihood that light exiting the ophthalmic device will be retro-reflected back into the ophthalmic device. 
       FIG. 15C , for example schematically illustrates a planar window  224  on the mask corresponding to the optically transparent section  224  that does not have an AR coating. The window  224  is shown receiving a bundle of rays  265  of light that are focused down by a focusing lens  270  at the output of the ophthalmic device. This focusing element  270  may be a lens (e.g., in an ocular) that outputs a focused beam of light from the ophthalmic device (e.g., OCT instrument). The focused bundle of rays  265  is show centered about a central axis  267  of the optical path from the ophthalmic device to the mask that corresponds to an optical axis  267  of the ophthalmic device (e.g., the optical axis of the focusing lens  270 ). The focused bundle of rays  265  may correspond to rays of light simultaneously provided with flood illumination or rays of light sweep through the range of angles over a period of time by the beam steering optics (e.g., movable mirror).  FIG. 15C  illustrate how, in either case, the bundle of rays  265  propagating along the optical path from the ophthalmic instrument to the eye can be reflected back toward the ophthalmic device at an angle within the collection angle defined by the numerical aperture of the lens  270  such that this light would propagate back along the same path to the ophthalmic device and re-enter the ophthalmic device possibly interfering with the signal. 
       FIG. 15D , for example schematically illustrates a planar window  224  on the mask having an AR coating thereon. Accordingly, the rays of light reflected from the mask window  224  are shown attenuated as back reflection is reduced by the AR coating. 
       FIG. 15E , for example schematically illustrates a planar window  224  on the mask without an AR coating that is tilted or sloped such that the normal (shown by dotted line) to the window is disposed at an angle, β, with respect to the central axis  267  of the optical axis from the exit pupil or ocular/eyepiece of the ophthalmic device to the window. The mask window receives a bundle of rays  265  of light (either simultaneously during flood illumination or more sequentially in a beam steering approach) focused down by a focusing lens  270  at the output of the ophthalmic device. The maximum ray angle or cone angle of the focused bundle of rays  265  is shown as a. In this example, |β|α, where α is the cone angle measured as a half angle as shown. In various embodiments, |β|−Δ&gt;α. As discussed above, A is the angle at which the probe beam can be offset with respect to the probe optical path so as not to be coupled back into the OCT instrument via retro-reflection and thereby disrupt the OCT signal by introducing noise. (See  FIG. 15B .) Accordingly, rays in the bundle of rays  265  propagating along the optical path from the ophthalmic instrument to the eye are not reflected back toward the ophthalmic device at an angle within the collection angle defined by the numerical aperture of the lens  270  such that this light does not re-enter the ophthalmic device. Tilting or sloping the window  224  sufficiently beyond the angle of the steepest ray of light from the probe beam can reduce retro-reflection. As discussed above, in various embodiments, the magnitude of the tilt or slope angle β is larger than the cone angle α, where α is the cone angle measured as a half angle as shown and is a positive value, or the magnitude of the tilt or slope exceeds the angle of the ray  268  exiting the ophthalmic device (e.g., exiting the ocular lens  270  shown in  FIG. 15E ) that is incident onto the mask window at the largest angle providing greater deflection away from the optical axis  267  for that ray  268 . Accordingly in various embodiments, |β|&gt;α thereby increasing the amount of rays that are not retro-reflected back through the lens  270  and into the ophthalmic device. As discussed above, in various embodiments, |β| exceeds α by at least Δ. The magnitude of the tilt or slope angle β of the optically transparent section  224  may thus be greater than the cone angle α established by the f-number or numerical aperture of the ophthalmic device. In some embodiments, one or more of these relationships are true for 50-60%, 60-70%, 70-80%, 80-90%, 90-95%, 95-98%, 98-99%, or 99-100% of the light from the probe beam (e.g., as rays are swept through the range of angles to provide raster scanning). Combinations of these ranges are also possible. 
     In addition to being tilted or sloped, the optically transparent sections  224  may also be coated with an anti-reflective coating as described above. In some embodiments, the respective portion of the optically transparent sections  224  is tilted or sloping upward or downward, as illustrated in  FIGS. 14A-D . In other embodiments, the respective portion of the optically transparent sections  224  is tilted or sloped temporally or nasally, or in a combination of upward/downward and nasal/temporal directions. 
       FIGS. 16A-D  illustrate a mask  300  for performing an eye exam according to an embodiment. The mask  300  is similar to the mask  200  shown in  FIGS. 14A-14D , except that two of the one or more substantially optically transparent sections  224   a  and  224   b  are tilted or sloped temporally or nasally in opposite directions with respect to each other. In an embodiment, the two substantially optically transparent sections  224   a  and  224   b  are tilted or sloped symmetrically away from the nose and nasal lines or centerline. In other embodiments, combinations of tilt directions are possible. For example, according to some embodiments, one optically transparent section  224   a  is tilted or sloped upward or downward, and the other optically transparent section  224   b  is tilted or sloped nasally or temporally. In some embodiments, a portion of the optically transparent sections  224  that intersect the incident light beam is planar, as illustrated in  FIGS. 14A-14D and 15A-15E . In other embodiments, a portion of the optically transparent sections  224  is curved, as discussed below. 
       FIGS. 17A-17C , for example, illustrate how curved windows  224  can be used as the optically transparent sections  224  of a mask and the effect of such curved windows on an incident probe beam  265 . In certain embodiments, depending on the placement of the incident beam  265  with respect to the mask window  224 , the window may provide a perpendicular surface for many of the rays of light in the beam thereby causing retro-reflection back into the channels of the ophthalmic instrument thereby contributing to noise in the signal. 
       FIG. 17A , for example, shows a curved window  224  without an AR coating having a center of curvature  272  that is located at the focus point  274  of the optics  270  of the ophthalmic device. Such alignment can cause a significant portion of the light to be retro-reflected back into the ophthalmic device. The focus point  274  of the optics  270  in the ophthalmic device may comprise the focal point of the lens or optics in the ophthalmic system (e.g., in the ocular or eyepiece or left or right output channel). 
       FIG. 17B  shows a curved window  224  without AR coating having a center of curvature of the window that is behind or beyond the focus point of the lens  270 . This positioning may be determined in part by the mask and the interconnection between the mask and the ophthalmic device that establishes the spacing between the ophthalmic device and the eye of the subject wearing the mask. In  FIG. 17B , rays of light are retro-reflected back toward the ophthalmic device at an angle within the collection angle defined by the numerical aperture of the lens  270  such that this light re-enters the ophthalmic device. 
     In contrast,  FIG. 17C  shows a curved window  224  without AR coating having the center of curvature that is in front of the focal point  274  of the optics. As discussed above, this positioning may be determined in part by the mask and the interconnection between the mask and the ophthalmic device that establishes the spacing between the ophthalmic device and the eye of the subject wearing the mask. Some of the rays on the outer parts of the cone of rays  265 , including the ray  268  directed at the largest angle are not retro-reflected back toward the ophthalmic device at an angle within the collection angle defined by the numerical aperture of the optics  270  such that this light does not re-enter the ophthalmic device. However, rays closer to the optical axis  267  are closer to being perpendicular with the normal of the window such that those rays are retro-reflected back toward the ophthalmic device at an angle within the collection angle defined by the numerical aperture of the optic  270  and thus re-enter the ophthalmic device. In various embodiments where the ophthalmic device is a beam-scanning device such as an OCT device or a scanning laser ophthalmoscope, a small offset angle between the cone of rays  265  and the slope of the curved window  224  is sufficient to sufficiently reduce or prevent retro-reflection of light into the ophthalmic device. 
       FIGS. 17D and 17E  schematically illustrate shifts of the center of curvature of the window to the left and the right.  FIG. 17D  shows a curved window  224  without AR coating having a center of curvature of the window that is to the left of the focus point and optical axis  267  of the lens  270 . This positioning may be determined in part by the mask and the interconnection between the mask and the ophthalmic device that establishes the spacing and positioning between the ophthalmic device and the mask as well as the eye of the subject wearing the mask. In  FIG. 17D , rays of light that intersect the curved window  224  to the right of its center of curvature are retro-reflected at an angle that is substantially directed away from the lens  270  and the optical axis  267 . Light that intersects the window  224  to the left of its center of curvature is retro-reflected back toward the ophthalmic device at an angle within the collection angle defined by the numerical aperture of the lens  270  such that this light re-enters the ophthalmic device. 
     Similarly  FIG. 17E  shows a curved window  224  without AR coating having a center of curvature of the window that is to the right of the focus point and optical axis  267  of the lens  270 . As discussed above, this positioning may be determined in part by the mask and the interconnection between the mask and the ophthalmic device that establishes the spacing and positioning between the ophthalmic device and the mask as well as the eye of the subject wearing the mask. In  FIG. 17E , rays of light that intersect the curved window  224  to the left of its center of curvature are retro-reflected at an angle that is substantially directed away from the lens  270  and the optical axis  267 . Light that intersects the window  224  to the right of its center of curvature is retro-reflected back toward the ophthalmic device at an angle within the collection angle defined by the numerical aperture of the lens  270  such that this light re-enters the ophthalmic device. 
     In these examples the windows  224  are spherical. In other embodiments, however, the window  224  may have a curved surface other than spherical, e.g., aspheric surface curvature. In addition to being tilted or sloped, the curved optically transparent sections  224  may also be coated with an anti-reflective coating as described above. 
       FIGS. 18A-D  illustrate a mask  300  for performing an eye exam similar to the mask  200  shown in  FIGS. 14A-14D , except that two of the one or more substantially optically transparent sections  224   a  and  224   b  are curved. In particular, the substantially optically transparent sections  224   a  and  224   b  have outer surfaces as seen from the front of the mask having a convex shape. These curved surfaces may be spherical in shape or may be aspherical. For example, the curved surfaces may be an ellipsoidal surface or an oblate spheroid surface, or have a shape characterized by a higher order polynomial or be combinations thereof. Other shapes are possible. In various embodiments, the surface is more flat at the center of the substantially optically transparent section and curves or slopes more steeply away from the center of the substantially optically transparent section as shown by  FIG. 18A-D . In some embodiments, the mask has a size and the substantially optically transparent sections are disposed such that the flatter central portions of the substantially optically transparent section are along the line of sight of the wearer. Accordingly, in various embodiments, the surface is flatter closer to the normal line of sight and slopes more steeply away from the normal line of sight. 
     Various embodiments of masks having optically transparent sections  224   a  and  224   b  that are curve and may be plano and have negligible optical power. Not having optical power will likely contribute to the comfort and viewing experience of the wear. Accordingly optically transparent sections  224   a  and  224   b  may have anterior and posterior surfaces having shapes that together provide that the optically transparent sections  224   a  and  224   b  have substantially zero diopters of optical power. In some embodiments, however, the optically transparent sections  224   a  and  224   b  may have optical power such as to accommodate individuals who need refractive correction. 
     In some embodiments, the angle of incidence varies across transparent section  224 . A curved window  224  depending on the shape and/or position with respect to the focus of the probe beam may cause the angle of incidence to vary across the transparent section  224 . 
       FIG. 19  schematically illustrates a window  224  of a mask disposed in front of a pair of eyes such that most of the rays of light from the incident beam are reflected at angles beyond the collection angle within the numerical aperture of the optics  270  or exceeds an offset angle Δ described above for beam-scanning devices. Accordingly, most of the light does not re-enter the ophthalmic device. In particular, the window  224  is sloped except for at the centerline where the nose of the wearer is located. Additionally, the window has a slope that increases in magnitude temporally. Moreover, the window is sloping such that all the rays in the cone of rays  265  of the incident beam are directed temporally upon reflection (unlike in the examples shown in  FIGS. 17A-C ). 
     In the example shown in  FIG. 19 , the window  224  has a slope and curvature that increases in magnitude temporally such that the slope or curvature is maximum at the periphery or edges  273  of the window  224 . This slope or curvature at the location of the line of sight (e.g., within a range of interpupilliary distances between 50-80 mm or 25-40 mm from the centerline) is sufficiently high in magnitude to exceed the angle of the ray  268  exiting the ophthalmic device (e.g., exiting the ocular lens  270 ) at the largest angle that is incident onto the mask window  224 . Additionally, the slope or curvature of the window  224  is sufficently high in magnitude to deflect all or substantially all or at least most of the other rays away from the optical axes  267  of the output channels of the ophthalmic device. At each point where rays from the probe beam intersect the window  224 , the normal to the window surface is oriented with respect to the cone of rays  265  to deflect the ray outwards or to retro-reflect the probe beam at an angle Δ described previously for beam-scanning devices. Moreover, the rays are deflected sufficiently so as not to be retro-reflected at an angle within the collection angle defined by the numerical aperture of the output channel of the ophthalmic device such that this light is not coupled back into the ophthalmic device so as to interfere with the signal (e.g., the OCT signal). 
     Additionally, in various embodiments, the width of this curved window  224  may be sufficient to account for the lateral position and movement of the oculars or output channels of the ophthalmic device. Increasing the interpupillary distance of the pair of output channels of the ophthalmic device effectively pushes the outermost ray  268  more temporally. Accordingly, the width and curvature of the window  224  on the mask can be established to ensure that half, or most, or substantially all, or all the rays of light from the left and right output channels of the ophthalmic instrument are at a given instant in time or over the range of angles swept during a raster scan not incident on the mask window at an angle where the rays are retro-reflected back at an angle within the collection angle defined by the numerical aperture of the channels such that the light is collected by the channels and introduces noise to the signal. For example, if the angle of the ray  268  exiting the left and right channels of the ophthalmic device at the largest angle is 35 degrees (e.g., if the cone angle α is ±35°, and the maximum lateral position of those rays is 40 mm from the centerline  279  or nose line on the window of the mask, a shape can be configured for the window that ensures that none or substantially none of the rays are incident on the transparent window in a perpendicular orientation and instead cause most, all, or substantially all the incident light to deflect outside the collection angle defined by numerical aperture of the left and right channels of the ophthalmic devices. 
     As discussed above, the substantially optically transparent sections  224   a  and  224   b  have outer surfaces as seen from the front of the mask having a convex shape and are aspherical. For example, the curved surfaces may be ellipsoidal, toroidal, or have a shape characterized by a higher order polynomial or combinations thereof. 
     Additionally, in various embodiments the optically transparent sections  224   a  and  224   b  are plano and have negligible optical power. The optically transparent sections  224   a  and  224   b  may have anterior and posterior surfaces having shapes that together provide that the optically transparent sections  224   a  and  224   b  has substantially zero diopters of optical power. In some embodiments, however, the optically transparent sections  224   a  and  224   b  may have optical power to accommodate individuals who need refractive correction. 
     Moreover, the transparent section  224  can be comprised of a curved transparent outer surface sufficiently sloped such that the angle of incidence of the rays of light output by an accompanying OCT machine when interfaced with the mask is not normal to the transparent section  224  at most or substantially all the points of incidence on transparent section  224  and the slope or tilt is configured to deflect the rays away from the optical axis and outside the collection angle of the OCT machine (e.g. |β|&gt;α). In some embodiments, such as beam-steering optical devices, the difference between angle |β| and angle α is be greater than an angle Δ such that |β|—Δ≥α to prevent any retro-reflected beam from impinging on the beam-steering device, such as a galvanometric mirror or MEMS mirror, and being sensed by the device. In some embodiments, this relationship is true for 50-60%, 60-70%, 70-80%, 80-90%, 90-95%, 95-98%, 98-99%, or 99-100% of the light from the probe beam as used (e.g., flood illumination or swept) to generate images by the ophthalmic device or combinations of these ranges. 
     Accordingly, in various embodiments, only 3-5% or 2-4%, or 1-3% or 0.5-1% or 0.1-0.5% or 0.05-0.1% or 0.01-0.05% of the light is reflected back into the ophthalmic device. 
       FIGS. 20A-D  schematically illustrate a mask  300  for performing an eye exam having transparent sections  224  with curvatures such as shown in  FIG. 19 . Accordingly, the transparent sections  224 , sometimes referred to herein as a mask window or curved transparent section, has wrap and sweeps back progressively with distance from a centerline of the mask (nasal line)  273  where the nose of the wearer would be positioned. Additionally, the mask window also has curvature in the superior-inferior meridian. Accordingly, this mask may reduce retro-reflection of light from the optical coherence tomography instrument back into the instrument. 
     In some embodiments, the curved transparent section  224  extends across all of distal portion  218 . In some embodiments, curved transparent section  224  is only a portion of distal portion  218  (e.g., see  FIGS. 21A-21D  in which the optically transparent section does not extend to or is displaced from the lateral edges of the mask). As shown, the mask has a front sheet that sweeps backward (e.g., posterior) and outward (e.g., lateral) from the centerline  279  and provides suitable curvature to reduce reflection back into the OCT instrument and thereby reduce noise on the OCT signal. 
     In certain embodiments for example, the mask includes left and right substantially optically transparent sections  224   a ,  224   b  disposed on left and right sides of the centerline  273 . The left and right substantially optically transparent sections  224   a ,  224   b  may be disposed with respect to each other to accommodate interpupillary distances (see  FIG. 19 ) between about 50-80 mm, for example, for adults. Accordingly, the distance between the normal line of sight and the centerline (which can be centered on the nose of the patent) is about 25-40 mm. In some embodiments, at least the right substantially optically transparent section  224   a  (or the left section  224   b  or both) has at least a portion thereof that is sloped such that at a location on the right substantially optically transparent section  224   a  (left section  224   b  or both) that is 30 mm from the centerline (e.g., lateral of the superior inferior meridian), the right substantially optically transparent sections is sloped by at least 10° or more, at least 20° or more, at least 30° or more, at least 40° or more, at least 50° or more up to 70° or 80° or 90°, with respect to a line through that location that is parallel to the centerline. This angle may be established by the cone angle α discussed above and can have a magnitude greater than 10° such as more than 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, up to 70° or 80° or 90° etc. The right substantially optically transparent section (or left section or both) may have the same slope magnitude or be increasingly sloped (for example, have a magnitude greater than for example 10° 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, or) 60° at locations progressively more temporal from the location (e.g., greater than 30 mm in distance from the centerline) at least to about 35 mm or 40 mm etc. from said centerline. In some embodiment, the location can be 20 mm, 22.5 mm, 25, mm, 27 mm, 29 mm, 31 mm, 33 mm, 35 mm, 37 mm, or 39 mm, or any range therebetween. In some embodiments, at 25 mm from the centerline, the magnitude of the slope may be greater than for example 10° 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, or 60° and/or the slope may exceed the cone angle such that the outermost ray of light from the ocular in the ophthalmic instrument is deflected away from the optical axis of the ocular. Likewise, for locations progressively more temporal, the optically transparent section may be sloped (for example, may have a slope with magnitude greater than for example 10° 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°), may have constant slope, or varying slope, e.g., increasingly sloped. Additionally, in some embodiments, the right (left or both) substantially optically transparent section(s) is sloped by at least 15°, 17°, 19°, 21°, 23°, 25°, 27°, 29°, 31°, 33°, 35°, 37°, 39°, 41°, 43°, 45°, 47°, 49°, 51°, 53° or 55°, in magnitude at said location or ranges therebetween. Accordingly, in some embodiments the substantially optically transparent section sweeps back as illustrated in  FIG. 19 . 
     Likewise, the window exhibits wrap. In some embodiments, the window wraps at least partially around the side of the face or at least begins to wrap around the side of the face. This curvature is desirable where the rays of light from the ophthalmic instrument might intersect the optically transparent window. Since different subjects will have different interpupilary distances, and the ophthalmic instrument may be adjusted accordingly to direct the probe beam through the pupil of the eye, the rays from the probe beam may be incident over a range of locations on the substantially optically transparent sections. A window that exhibits wrap over a region thereof may thus be desirable to reduce retro-reflection back into the instrument. In various embodiments, windows that sweep rearward with distance progressively more temporal of the centerline  273  of the mask  300  are useful in deflecting light temporally and outside the collection angle of the ophthalmic device. The slopes may be substantially constant in the temporal region or may be varying. 
     Although  FIG. 19  is a useful reference for the discussion above where curvature is shown along a nasal-temporal meridian, in considering the superior-inferior meridian, reference to  FIGS. 17A-E  may be beneficial. In various embodiments, the window is curved along the superior-inferior meridian. This curvature as well as the distance of mask from the ocular on the ophthalmic instrument (as established by the mechanical interface between the mask and the ophthalmic device) may be such that a plurality of, many, possibly most, or substantially all rays in the bundle of rays from the ocular are deflected upward or downward and outside the collection angle of the ocular. 
     In various embodiments, combinations of tilt directions and curvature of transparent sections are possible.  FIGS. 21A-21D, 22, 23, 24, 25A-25D, 26, and 27  show additional designs having differently shaped windows.  FIGS. 21A-D  as well  FIGS. 26 and 27  schematically illustrate a design having a planar portion  291  of the substantially transparent section that is located more nasally and an adjacent planar sloping portions  293  located temporally. A transition  295  between these portions  291 ,  293  is curved. In certain embodiments, this transition  295  has a curvature of a circular arc having a center and radius of curvature. The sloping portions may slope along a nasal-temporal direction. Curvature or slope in the superior-inferior direction is negligible. Additional discussion regarding this design is provided below in connection with  FIGS. 28A-D . 
       FIGS. 22-24 and 25A -D show transparent sections that are curved in both nasal-temporal meridian and superior-inferior meridian. ( FIGS. 22 and 23  show the same compound curved surface as in  FIG. 24 .) In various embodiments such as shown in  FIG. 25B , the curvature or slope of the substantially transparent section  301  in the nasal-temporal direction is negligible closer to the centerline until reaching a temporal location where the magnitude of the slope increases temporally to generate a curved temporal section that sweeps backward. The curvature or the magnitude of the slope of the substantially transparent section  301  along the superior-inferior meridian starts out high in magnitude at the inferior location, reduces in magnitude to a negligible amount halfway between the inferior and superior extent of the convex shaped substantially transparent section  301  and increases again at the superior locations. The curvature is such that the magnitude of slope increases with increasing distance superiorly and inferiorly beyond the central flat non-sloping region. The curvatures do not slope or the slope is substantially negligible along the nasal temporal meridian in this central flat non-sloping region as well. In various embodiments this central flat non-sloping region can be ⅓ or ½ to ¾ the extent of the convex shaped substantially transparent section along the nasal temporal meridian, the superior inferior meridian, or both. 
       FIGS. 28A-D  illustrate some of the design considerations entailed in various embodiments of the mask window. For certain ophthalmic instruments, different modes of operation may involve use of probe beams with different characteristics. 
       FIG. 28A  for example, illustrates a mode of operation where an OCT instrument is configured to output a planar non-focused wavefront. Optics in the OCT instrument are configured to be telecentric.  FIG. 28A  therefore shows on a plot of angle of incidence (in degree) versus distance (in mm) from the centerline, the output from the ocular or eyepieces for the left and right channels of the ophthalmic device (e.g., OCT instrument). The plot shows an angle of 0° for each of the rays across the aperture of the ocular for both the left and right channels. 
       FIG. 28B  illustrates a mode of operation where an OCT instrument is configured to output beam that sweeps across a range of angles α as discussed above. A plot of angle of incidence (in degree) versus distance (in mm) from the centerline shows the output of the ocular or eyepieces for the left and right channels of the ophthalmic device (e.g., OCT instrument). These plots show the change in angle for the different rays across the aperture of the ocular for both the left and right channels. 
     The OCT instrument is configured to provide modes of operation using probe beams characterized by the plots shown in  FIGS. 28A and 28B . Accordingly, in various embodiments, a mask that can reduce retro-reflection back into the OCT system for both of these modes is beneficial. The signal-to-noise ratio can thereby be increased by curtailing introduction of noise into the signal by retro-reflection off the mask. Accordingly,  FIG. 28C  shows the combination of angles of incidence in the probe beam for the two modes on a single plot. 
       FIG. 28D  presents a solution for reducing retro-reflection. As discussed above, rays perpendicularly incident on the mask will be retro-reflected back into the OCT instrument and introduce noise to the OCT signal. However, by adding a slight offset A to the reflected beam such that the beam is not incident perpendicular on the mask and does not reflect directly back in the same direction the amount of rays that return back into the OCT instrument can be reduced. The plot in  FIG. 28D , shows the addition of this offset. In particular, an offset of 1° has been provided. 
     In this example, the inter-optical distance, the distance between the centers or optical axes of the oculars or eyepieces, which is related to the interpupillary distance of the subject, was 54°. Accordingly, a line of sight for wearers would be expected to be at 27° in both directions from the centerline for each of the left and right eyes. The magnitude of the slope of the mask is therefore set to increase continuously in the regions between 27 mm and about 38 mm where the magnitude of the slope reaches a maximum (just beyond the angle of the outermost ray in the bundle shown in  FIGS. 28A and 28B ). This curvature is to address the mode of operation represented by  FIG. 28B . The small 1° in the region between 0 mm and 27 mm is to address the mode of operation represented by  FIG. 28A  where the rays are each at an angle of incidence of 0° without the offset.  FIG. 28D  shows a cross-section of the mask. The cross-section shows a wide central region  291  between for the right eye between 0 and 27 mm without a large amount of slope, a transition region  295  between 27 mm and 38 mm where the magnitude of the slope is increasing, and a region  293  from 38 to 49 mm where the slope magnitude remains constant. A similar shape could be used for the left eye thereby providing a symmetrical configuration. 
     Other variations are possible. For example, in one embodiment, for the right eye, the magnitude of the slope at 27 mm could be set to be so large as to account for α+Δ, namely, β≥α+Δ at 27 mm. The transition region  295  could thus start around 13 or 14 mm and be complete by 27 mm where the magnitude of the slope could remain constant for distances beyond 27 mm (e.g., in region  293 ). In the region  291  between 0 to 13 or 14 mm, the small slope offset of 1° or so could be introduced. A similar shape could be used for the left eye thereby providing a symmetrical configuration. 
     The various shaped windows may further include an AR coating as discussed above. 
     As illustrated in  FIGS. 15B, 26, and 27 , rays of light corresponding to the probe beam may be swept. For example, the probe beam (for OCT or SLO) may comprise a beam having a small beam width (e.g., 5 to 10 times or more smaller than the exit pupil of the ocular) that is swept across the focusing lens and/or exit pupil in the ocular of the ophthalmic device. Accordingly, only portions of the rays in the bundle of rays described above will be present at a given time. Nevertheless, in various embodiments, the beam sweeps through the different angles within the cone of angles, α, referred to above. Accordingly, as discussed above, the shape of the mask window can be configured to be sufficiently sloped such that these rays, and in particular, this small beam, is not retro-reflected back into the instrument to introduce noise into the signal as the beam is swept through the range of angles defined by the cone angle, α. 
     In some embodiments, similar to the mask  100  illustrated in  FIG. 1 , the proximal portion  254  of the mask  200  is inflatable or deflatable, and the rear surface  222  is configured to conform to contours of the patient&#39;s face and align the one or more substantially optically transparent sections  224  of the distal portion  218  with the patient&#39;s eyes when the proximal portion  254  is inflated or deflated. In some embodiments, the mask  200  includes an inflation port (not shown) providing access to inflate or deflate the proximal portion  254 . In some embodiments, the proximal portion  254  has two cavities  260   a  and  260   b  extending from the rear surface  222  toward the distal portion  218 . The two cavities  260   a  and  260   b  are aligned with the one or more substantially optically transparent sections  224  and defining two openings on the rear surface  222  to be aligned with the patient&#39;s eyes. The rear surface  222  is configured to seal against the patient&#39;s face so as to inhibit flow of fluid into and out of the two cavities  260   a  and  260   b  through the rear surface  222 . In some embodiments, the mask  200  includes an ocular port (not shown) providing access to at least one of the two cavities for gas or fluid flow into the at least one of the two cavities  260   a  and  260   b.    
     In some embodiments the mask is reusable. In other embodiments, the mask is single use or disposable and intended to be used by one patient, subject, or user, and subsequently disposed of and replaced with another mask for use for another person. 
     In various embodiments, the optical transparent sections  124  of the mask are configured to increase or maximize transmission of light, such as from an OCT device, and the proximal portions  154  and concaved rear surface  122  is configured to reduce or minimize transmission of light, such as ambient light or light not emanating from an OCT machine and may be opaque and include opaque sides. For example, the proximal portions  154  may have sides that are substantially non-transmissive to visible wavelengths. These sides may for example block 80-90%, 90-95%, 95-99%, and/or 99-100% of ambient visible light. Reduction of ambient light may for example assist in keeping the patient&#39;s pupils dilated. Conversely, the optically transparent sections may have a transmittance of 70-80%, 80-90%, 90-95%, 95-99%, and/or 99-99.5%, or 99.5%-100% or any combination of these ranges in the wavelength range at which the ophthalmic device operates such as at 450 nm, 515 nm, 532 nm, 630 nm, 840 nm, 930 nm, 1060 nm, 1310 nm, or any combination thereof or across the visible and/or near IR wavelength range or at least 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, or 90% of that range. 
     Other methods and configurations for reducing retro-reflection back into the instrument can be used including any combination of the foregoing such as a combination of tilt and anti-reflective coatings. 
     Additionally, although various embodiments of the mask have been discussed above in connection with an optical coherence tomography device the mask may be used with other diagnostic instruments or devices and in particular other ophthalmic devices such as a scanning laser ophthalmoscope (SLO). One use for the AR coating on these goggles could be to increase transmission of emitted light into the eye. Optical instruments that sense back-reflected light (e.g. imaging instruments) often benefit from or require very sensitive instrumentation (e.g. avalanche photodiodes, interferometers, etc.) if the level of back-reflected light is low. Additionally, since the tissues in the eye are not very reflective, the low signal level of light back-reflected from the eye tissue to be imaged or evaluated by the ophthalmic imaging or diagnostic systems may be lost in noise if the ghost back-reflections are sufficiently high. As discussed above, reducing the optical interfaces that will be perpendicular to the incident beam at any point may advantageously reduce back-reflection that introduced noise. Various embodiments, therefore, employ tilting or curving the surface of the window. Additionally, signal can potentially be strengthened by increasing transmission of light (and consequently by reducing reflections) at every surface to increase or maximize power going both to and coming from the eye. This goal can be accomplished, for example, with AR coatings. Advantageously, in various embodiments, this increased transmission is accompanied by reduced reflections which improve the signal-to-noise ratio (SNR) and contrast in the images or data produced and reduce ghost artifacts that can appear as real objects, for example, in an OCT or other image. Other instruments may benefit for similar or different reasons. 
     While the invention has been discussed in terms of certain embodiments, it should be appreciated that the invention is not so limited. The embodiments are explained herein by way of example, and there are numerous modifications, variations and other embodiments that may be employed that would still be within the scope of the present invention. 
     For purposes of this disclosure, certain aspects, advantages, and novel features of the invention are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves one advantage or group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     As used herein, the relative terms “temporal” and “nasal” shall be defined from the perspective of the person wearing the mask. Thus, temporal refers to the direction of the temples and nasal refers to the direction of the nose. 
     As used herein, the relative terms “superior” and “inferior” shall be defined from the perspective of the person wearing the mask. Thus, superior refers to the direction of the vertex of the head and inferior refers to the direction of the feet.