Abstract:
In one aspect, there is provided a handheld vision tester comprising a display, cursor control, interface port, and camera. The display delivers a series of images making up vision tests to a user who interacts with the vision tests by using the display and cursor control of the handheld vision tester. The camera verifies the user is taking the vision tests. The results of the vision tests are stored in the handheld communication device. The interface port allows for communication of the stored results of the vision tests with external devices. In another aspect, there is provided a calibration system for the handheld vision tester. The calibration system includes a stand to hold the handheld vision tester and a reflective surface substantially parallel to a display of the handheld vision tester.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/176,885, filed by Michael Bartlett, et al. on May 9, 2009, entitled “Shape Discrimination Vision Assessment System,” incorporated herein by reference. 
     
    
     TECHNICAL FIELD OF THE INVENTION 
       [0002]    This invention relates to techniques for the design and implementation of a vision testing system including calibration techniques. 
       BACKGROUND OF THE INVENTION 
       [0003]    Vision testing is normally carried out today either through observation of vision testing charts or through professional evaluation including imaging of the inside of the eye and other advanced diagnostic tools. Professional evaluation is effective in analyzing many vision disorders, but is expensive and may not be available in rural and remote areas. Observation of vision testing charts is effective, but is bulky and cumbersome as the charts are normally mounted on a wall and the test subject must observe them from some distance. While limited, use of vision testing charts and professional evaluations are effective for many common vision disorders such as focusing disorders. However, there are some vision diseases, such as diabetic retinopathy, age-related macular degeneration, and other vision diseases where ongoing monitoring of vision is critically important. Such diseases may become active at specific times and, if not treated, could result in irrecoverable vision loss or even blindness. 
         [0004]    Consequently, a small and low-cost device that allows patients suffering from these diseases to conveniently monitor their vision is desirable. Techniques that help to ensure such a system operates properly so that it provides dependable test results are highly desirable. And additional techniques such as vision aids that help a patient in their daily life; electronic magnifier functions; auxiliary imaging and display systems; techniques to ensure the patient taking a test is the properly identified and is actively engaged; and other techniques to ensure accurate testing are also desirable. 
       SUMMARY OF THE INVENTION 
       [0005]    To address the above-discussed deficiencies of the prior art, in one embodiment, there is provided a handheld vision tester. In this particular embodiment, the handheld vision tester comprises a display, cursor control, an interface port, and a camera. The display delivers vision tests to a user. The user interacts with the vision tests by using the display and cursor control. The camera verifies that the user takes the vision tests. The interface port allows for communication of the results of the vision tests from the handheld tester to external devices. 
         [0006]    In another embodiment, there is provided a method of testing using a handheld vision tester. The method comprises verifying an identity of a user of the handheld device, displaying a series of images on the handheld device, accepting input from the user in response to the series of images displayed on the handheld vision tester, storing the response input in the handheld vision tester, and communicating the response input to a device external to the handheld vision tester. 
         [0007]    In yet another embodiment, there is provided a calibration system for use with a handheld vision tester. The calibration system comprises a calibration stand to hold the handheld vision tester and a reflective surface substantially parallel to a display of the handheld device. The calibration stand holds the handheld vision tester at a fixed distance to the reflective surface. 
         [0008]    The foregoing has outlined various features of the invention so that those skilled in the pertinent art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the pertinent art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the invention. Those skilled in the pertinent art should also realize that such equivalent constructions do not depart from the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    For a more complete understanding of the invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
           [0010]      FIG. 1  shows a handheld device suitable for running a vision test; 
           [0011]      FIG. 2   a  shows a handheld device mounted in a calibration stand; 
           [0012]      FIG. 2   b  shows a perspective view of a handheld device mounted in a calibration stand; 
           [0013]      FIG. 2   c  shows an image suitable for use for calibration; and 
           [0014]      FIG. 3  shows a fundus imaging system 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    In  FIG. 1 , an electronic handheld device  100  is shown. The handheld device  100  may include a case  102 , a display  104 , a cursor control  110 , a fingerprint sensor  114 , a camera  112 , a first button  106 , a second button  108 , a power connector  116 , and an interface port  118 . The display  104  may include touch-screen capability so that the handheld device  100  can be controlled by touching the display  104  in pre-specified locations or manners within certain timeframes. The fingerprint sensor  114  allows the handheld device  100  to identify the person using it. The cursor control  110  is a button that may be pressed to move a cursor across the display  104  and position it in a desired location. Pressing the cursor control  110  may also be used to trigger operations and to control the handheld device  100 . Alternative implementations of cursor controls include track balls, joysticks, touch pads, and other approaches may also be used in place of the cursor control  110  as shown in  FIG. 1 . The first button  106  and the second button  108  may be used to control the handheld device  100  and to operate functions of the handheld device  100 . It is noted that the handheld device  100  may be operated through manipulation of the display  104  if a touch-screen capability is included, through the cursor control  110 , through the fingerprint sensor  114 , through the first button  106  and through the second button  108 . Additional buttons and controls are possible including buttons and controls on the sides and back of the handheld device  100 . It is also possible to include additional buttons, displays, and other forms of input devices. 
         [0016]    The case  102  of the handheld device  100  may be constructed from metals, plastics, or other materials. While not shown in  FIG. 1 , the handheld device  100  may include removable panels on its front, back, or sides to allow batteries, memory cards, or optional accessories to be installed, connected, or removed. The power connector  116  allows the device to be powered from an external electrical power source that may supply AC or DC power to the handheld device  100 . The interface port  118  allows the handheld device  100  to be connected to an external host computer, external cameras, external calibration or test equipment, external accessories, or other systems or devices the user may desire to connect it to. It is also possible that the interface port  118  or the power connector  116  could be configured to supply battery power from the handheld device  100  to an external device or interface connected to them. The interface port  118  may be constructed from multiple physical interfaces and protocols. Some examples are Universal Serial Bus (USB), P1394, Ethernet, RS232, and many other possible interfaces. In addition to the interface port  118 , the handheld device  100  may include wireless connectivity. Bluetooth, IEEE802.11, Zigbee, and many other wireless communications protocols and radio electronics may be included in the handheld device  100 . The wired and or wireless connectivity of the handheld device  100  allows it to send information to a network service, host computer, or other computing device; and also allows for calibration, configuration, test protocols, software updates, and other useful information to be sent from a host computer or other data processing device or interface to the handheld device  100 . The procedure for allowing the handheld device  100  to either send data out over its wired or wireless interfaces or to receive information from other sources should normally include security features to ensure that the users information and privacy are not compromised and also to ensure that configuration, calibration, and other important factors of the handheld device  100  operation cannot be compromised illicitly or accidentally. 
         [0017]    The camera  112  can be used to ensure that the same person is taking the test throughout the test sequence and an image of the user can be compared to images from past tests to help ensure that the person taking the test is indeed the correct person. The handheld device  100  can perform this operation by image analysis of an image or images provided from camera  112 . Additionally, the camera  112  can be used to check that the user is awake, upright, and appears to be capable and actively engaged in taking the vision test. 
         [0018]    In addition to delivering vision tests to a user, the handheld device  100  can also serve as a vision aid to the user. The camera  112  can be used as a still image camera or as a video camera and allow the user to take images and then enlarge them on the display  104  so that they are easier to observe. In addition to enlarging the images, the handheld device  100  can also provide image or video processing capability to sharpen, detail, provide additional contrast, color tint, or otherwise alter the image or video sequence so that it is easier for the user to view it. Of course, additional cameras can be mounted on other parts of the handheld device  100  in addition or in place of the camera  112  shown in  FIG. 1 . For use as a vision aid, it may be beneficial, for example, to include a second camera on the handheld device  100  that points opposite the direction of the camera  112  shown (that is, this additional camera would point into the page in  FIG. 1 ). Additionally, a camera can be mounted behind the display  104  in place of or in addition to the camera  112  shown in  FIG. 1 . The camera  112 , as shown in the embodiment of  FIG. 1 , may be beneficial in generating an “enhanced mirror” since it faces the user and can simply put the image it has generated on the display  104  in an enlarged or enhanced view. Special cameras, such as night vision cameras, may also be included in the handheld device  100 . Of course, any other wavelength specific camera may be included in the handheld device  100 . In addition to displaying information, the handheld device  100  may also include image analysis capability to automatically recognize persons, places, or things by analyzing images taken from the handheld device&#39;s  100  camera (or cameras). It is also possible to add auxiliary displays to the handheld device  100  or to use the interface  118  or wireless connectivity to move images and/or video to an external video monitor. Auxiliary displays suitable for use with the handheld device  100  include LCD display panels, CRT displays, light processing display devices, head mounted displays, binocular display devices, virtual reality viewers, and many other types of displays. One example is use of the very small projectors that are now available and can be incorporated into small devices and allow images and video to be expanded for easy viewing. These small projectors are sometimes referred to as pico projectors. Such a pico projector may be physically integrated into the handheld device  100  or may be used as an external separate device connected to the handheld device  100  through a wired or wireless communication link. 
         [0019]    The functions of the handheld device  100  shown in  FIG. 1  may also be incorporated into electronic handheld devices that are already used for other functions. That is, the function delivered by the handheld device  100  may be implemented on a portable game console, a cellular phone, a personal digital assistant, a netbook computer, a notebook computer, a blood glucose meter, or many other electronic devices. The ability to combine many functions together into a single device allows for convenience for the user and also allows for beneficial combined functionality in some cases. For example, if the handheld device  100  of  FIG. 1  includes the function of a glucometer (also known as a blood glucose meter), the user can record their blood glucose level when each vision test is taken so that a more complete record of vision capability and blood glucose can be generated. Of course, other biomedical measurements of a user could also be recorded, such as, but not limited to, blood pressure, heart rate, pupil dilation, iris color changes, eyelash growth, enzyme levels, etc. If the handheld device includes a positioning technology such as the Global Positioning System (GPS), the records of vision testing can be location stamped so that the user can more easily remember where they took each test and what the testing conditions were. Of course, the handheld device  100  can easily include calendar and clock functions so that test results may also be time and date stamped. 
         [0020]    In  FIG. 2   a , a calibration stand  200  is shown with the handheld device  100  mounted in it. The calibration stand  200  comprises a base  202  and a mirror  204 . The calibration stand  200  positions the handheld device  100  at a fixed distance and orientation relative to the mirror  204  so that a test image  206  creates a reflection  208  that can be observed by the camera  112  (the camera is not explicitly visible in  FIG. 2   a , but it&#39;s relative position is clear from  FIG. 1 , so it is identified consistently by the numbering in  FIG. 2   a ). Please note that the test image  206  and the reflection  208  are shown just in front of the handheld device  100  and the mirror  204  in the cross sectional view shown in  FIG. 2   a . Of course, they would in practice actually appear on the surface of the handheld device&#39;s  100  display  104  and, respectively, on the surface of the mirror  204 , but such a view is not possible in a cross sectional drawing. The handheld device  100  is inserted into the base  202  and a self-testing and calibration sequence is initiated by the user to ensure that the handheld device  100  is operating properly and can provide good quality measurements. The handheld device  100  can display a wide range of images and observe them back through it&#39;s camera to ensure that the shape, color, contrast, size, and other aspects of the images are displayed as they should be. The calibration stand  200  is clearly desirable for such self-testing and self-calibration, but it is noted that this could be undertaken by simply holding the device in front of a reflective surface and initiating the self-testing and calibration sequence. Of course, given the potential for different distances, movement of the handheld device, and other factors, the use of a calibration stand  200  may be preferred. 
         [0021]    The base  202  may be fabricated from metals, wood, plastics, or other materials. It may include features such as accurately formed surfaces, keyed openings, mechanical guides, and other features to keep the handheld device  100  accurately and consistently in place. The base  202  may also include fabrics, cushions, gaskets, felt linings, or other features to protect the handheld device  100  from being scratched or damaged when it is inserted and removed from the base  202 . And the base  202  may also include mechanical features that secure the handheld device  100  such as straps, clamps, snaps, buckles, or other features. The mirror  204  may be a glass mirror or may be made from polished metals, metal film laminated on plastics or other materials, or may be constructed in other ways to provide a substantially reflective surface. Normally, the mirror  204  would be constructed to be highly reflective of visible light, but in the case that it has limited reflectivity or inconsistent reflectivity for some wavelengths of light, the handheld device  100  may compensate for this limitation through adjustment factors included in its calibration routine. Similarly, if the camera  112  provides higher sensitivity to some wavelengths of light, the handheld device  100  may compensate for it with information about the cameras  112  sensitivity as a function of wavelength. 
         [0022]    In another embodiment, the base  202  of calibration stand  200  could include an auxiliary camera in place of mirror  204 . In this embodiment, the auxiliary camera would be oriented toward the display of handheld device  100  such that test image  206  is captured by the auxiliary camera. The auxiliary camera could interface with handheld device  100  for calibration purposes or could interface with an external device to analyze calibration of the handheld tester. 
         [0023]    The handheld device  100  may keep track of calendar dates and times and require that it be operated through its self-testing and calibration sequence on a regular basis. The user may be reminded electronically of the need for this with visible, audible, or other signals or messages. The handheld device  100  may refuse to operate and collect user test results if it has not been acceptably self-tested and calibrated within a sufficient time interval. Further, if the handheld device  100  detects that it has possibly been modified, the case  102  has been opened, high levels of mechanical shock or acceleration have been measured, or other factors are present that bring the proper condition of the device into question; the handheld device  100  may demand that the user run the self-testing and calibration sequence with acceptable results before further testing takes place. 
         [0024]      FIG. 2   b  shows a perspective view of a handheld device  100  mounted in a calibration stand  200  including a base  202  and mirror  204 . This view is shown to avoid any confusion related to the similar view of a handheld device  100  in a calibration stand  200  shown in  FIG. 2   a . On the mirror  204 , a reflection  220  of the handheld device  100  is visible. This reflection  220  may be analyzed as already described with regard to  FIG. 2   a  by using the camera  112  to create an image of the reflection  220  and use of data processing functions in the handheld device  100  to analyze the calibration image  222  visible in the reflection  220 . Note that the camera  112  is not actually visible in  FIG. 2   b , but the camera reflection  224  of camera  112  is visible. The generation of a calibration image  222  will be discussed next with regard to  FIG. 2   c.    
         [0025]      FIG. 2   c  shows a calibration image  240  that may be used for calibration and testing of the handheld device  100  either through use of the calibration stand  200  or with a reflective surface as described above. In the course of testing and calibrating the handheld device  100 , a calibration image  240  is displayed on the display  104  and the reflection of the calibration image  240  is observed with a camera  112 . A very wide variety of calibration images  240  may be used. The calibration image  240  shown in  FIG. 2   c  includes crosses  244 , circles  246 , squares  248 , and triangles  250  inside display boundary  242 . The shapes shown in the calibration image  240  are shown in black and white for convenience. However, a very wide variety of shapes, images, features, shadings, textures, colors, line weights, and other aspects may be used in an image for calibration and handheld device  100  testing purposes. For example, rectangles, wavy lines, ellipses, trapezoids, and very many other shapes and images displayed in all possible colors, shadings, brightness levels, and other factors may be used as test images or as part of a test image. And, in addition to stationary images, moving images and video images may be used. Many standard video and image calibration charts may also be used. 
         [0026]      FIG. 3  shows a fundus imaging system  300 . A cross section of an eyeball  302  and a schematic of how illumination might be applied so that fundus photos of the retina  304  may be taken are shown. Fundus photography is widely used to take images of the retina  304  of the eyeball  302 . Fundus photos are taken by using special lighting systems to illuminate the inside of the eye and to then take a photograph of the retina  304  through the pupil of the eyeball  302 . In  FIG. 3 , light emitting diodes  310  are shown to illuminate the inside of the eye. Other lighting techniques are possible such as scanning lasers, incandescent bulbs, and other techniques. Light emitting diodes  310  are presently preferred for their small size, low cost, and high efficiency. While only two light emitting diodes  310  are shown in  FIG. 3 , the actual embodiment might include a full circle of light emitting diodes  310  around the lens  318  and imager  312 . Many possible forms of the camera  112  of the handheld device  100  are possible, but most are based on a simple lens  318  and imager  312 . Many types of imagers such as CMOS image sensors, CCD (Charge Coupled Device) imagers, and other imagers may be used. Also, the lens  318  may be a fixed lens or a variable focal length lens and may be formed from glass, plastic, or other possible materials. It is noted that the camera function made up of the lens  318  and imager  312  may be those of the camera  112  shown in  FIG. 1  or may be a separate camera mounted in the handheld device  100  or may be a separate camera that is connected electronically or can pass its image to the handheld device  100 .  FIG. 3  also includes a schematic feature of the upper eyelash  306 , the lower eyelash  308 , a diagram center line  314 , and illumination reference lines  316 . 
         [0027]    The addition of a fundus imaging system  300  to the handheld device  100  opens the possibility to couple analysis of an image of the retina  304  with the results of vision testing. If areas of the vision field are determined to show distortion, reduced clarity, limited acuity, or other effects, these can be compared to areas of the retina corresponding to that area of the vision field. In this way, automated or professional analysis of the fundus image can include additional attention in areas where the vision field showed limited or poor performance. And, in a reverse fashion, areas of the fundus image that show signs of eye disease can be given additional attention in the automated vision testing. The combination of both vision testing and fundus image analysis is novel and is a key aspect of some possible embodiments of this invention. 
         [0028]    Although the description above contains many specificities, these should not be construed as limiting the scope of the invention, but as merely providing illustrations of some of the presently preferred embodiments of this invention. Thus the scope of the present invention should be determined by the appended claims and their legal equivalents, rather than by the examples given. Those skilled in the art to which this application relates will appreciate that other and further additions, deletions, substitutions and modifications may be made to the described embodiments.