Patent Description:
Disclosed herein are systems and methods for alignment of the eye for ocular imaging.

In ocular imaging, proper alignment of the optical axes of the subject's eye and the imaging optics is a prerequisite to avoid unwanted reflections quality ocular image acquisition. However, there are <NUM> degrees of freedom (<NUM> on the part of the subject's eye, and <NUM> on the part of the imaging system, making this a nontrivial task. Traditional approaches to achieving alignment rely on an operator manually aligning the axes of the imaging device to that of the subject's eye, or robotic (automated) alignment of the axes of the imaging system to that of the subject's eye. Both trained operators and robotic alignment add cost and complexity to the imaging workflow. For example, manual handheld fundus cameras require the operator to manually position a camera in three-dimensional space along <NUM> degrees of freedom, and often require an integrated screen to view the eye, while the head of the subject is partially restrained leaving <NUM> degrees of freedom, for a total of <NUM> degrees of freedom. Traditional manual desk-mounted fundus cameras require the operator to manually steer the camera with a joystick, <NUM> degrees of freedom, while the subject's eye is restrained with a chinrest and headband as well as fixation, leaving <NUM> degrees of freedom in total. Automated or semi-automated fundus cameras require complex motors, additional cameras and sensors, and built-in image processing to drive the automated alignment along <NUM> degrees of freedom, thereby adding significant cost, and also restrain the subject's eye using chinrest, headband and fixation.

The human eye, however, is the endpoint for a highly versatile cybernetic system that can align the optical axis of the eye with respect to external objects along <NUM> degrees of freedom. Because there is a need in the art for an alignment system with reduced cost, complexity, and ease of operation, it is attractive to use the natural alignment of the human body. <CIT> describes an imager, a module for an imager and an imaging system and method suitable for ocular imaging, the module having an optical aperture extending therethrough that aligns with an image sensor to form an imaging channel wherein the sensor is operable to image a subject within an optical axis of the imaging channel. <CIT> describes a fundus imaging system in which images are obtained using selective illumination of a sector of the field of view of the fundus. <CIT> describes a head mounted eyepiece worn by a user, the eyepiece including an optical assembly through which the user views the surrounding environment and displayed content.

Disclosed herein are various ocular alignment system embodiments for aligning a subject's eye with an optical axes of an ocular imaging device. The implementations comprise one or more guide lights and one or more baffles configured to mask the one or more guide lights from the subject's eye such that the one or more guide light is only visible to the subject when the optical axis eye of the subject is aligned with the optical axis of an ocular imaging system along one or more degrees of freedom.

In certain aspects, disclosed is a device for aligning the optical axis of a subject's eye with the optical axis of an ocular imaging device comprising a housing, the housing comprising a first end, a second end, an outer surface, and an inner surface, wherein the inner surface defines a luminal space and wherein the luminal space is configured to allow for passage of the optical axis therethrough; a plurality of guide light assemblies disposed within the housing, each guide light assembly comprising a body, the body comprising a first side and a second side opposite the first side, wherein the second side faces the luminal space a channel defined in the body, wherein the channel extends from the body first side to the body second side, wherein the channel forms an opening in the body second side; a guide light disposed within the channel, wherein the guide light is configured to emit rays out of the opening; and a baffle disposed transversely in the channel between the guide light and the opening and configured to mask rays from the guide light, wherein the baffle further comprises a slit configured to allow passage of rays along a path of ocular alignment; and a plurality of secondary baffle assemblies disposed on the housing second end, wherein each of the plurality of second baffle assemblies is configured to mask rays emitted from one of the plurality of guide light assemblies, wherein each of secondary baffle assemblies further comprises a slit configured to allow passage of rays along a second path of ocular alignment, wherein the rays from each of the plurality of guide light assemblies are visible to the subject when the optical axis of the subject's eye is in alignment with respect to the optical axis of the device and not visible when the optical axis of the subject's eye is out of alignment with respect to the optical axis of the device.

A method of aligning the optical axis of a subject's eye with the optical axis of an ocular imaging device not part of the invention is also disclosed comprising providing a first set of guide lights along the line connecting the optical axes of the subject's eye and of the ocular imaging device; and providing one or more baffles, configured to mask the rays emitted from first set of guide lights from view of the subject such that first set of guide lights is only visible to the subject when the eye of the subject is aligned with the optical axis of an ocular imaging system.

As will be realized, the invention is capable of modifications in various obvious aspects, all without departing from the scope of the present invention.

The instant disclosure relates to optical imaging system embodiments for imaging the eye of a subject which allow a subject to properly position and align the optical axis of his eye with the optical axis of an ocular imaging system in response to visual cues from the system. This is in contrast to known optical imaging systems where the subject's eye position is fixated as much as possible and alignment is achieved by adjusting the position of camera elements with respect to that eye. Thus, the disclosed implementations utilize the precise oculomotor alignment system of the human eye to align to the optical axis of the imaging system, instead of relying on the trained operators or expensive servo motors to align the optical axis of the imaging system to that of the human eye. The disclosed systems are further able to provide for precise oculomotor alignment without the use of mirrors or lenses to direct light to the desired angle along the optical path.

According to certain embodiments, the system comprises a camera (for example a fundus camera) having an image sensor and one or more guide lights positioned laterally between the image sensor and the subject's eye. In certain embodiments, the system further comprises one or more baffles positioned between the one or more guide light and subject's eye. The one or more baffle is configured to occlude the subject's view of the one or more guide light until the eye of the subject is properly positioned and aligned translationally (along x, y, z axes). Further embodiments have additional lights to provide for alignment rotationally (along θ, η, and ζ axes) with respect to the optical path of the imaging device, resulting in optimal image acquisition.

In certain embodiments, as best seen in <FIG> and <FIG>, the guide light is a ring light <NUM>, which is a light forming a substantially ring-like shape. As best shown in <FIG>, the guide light <NUM> is masked by a baffle <NUM>, which, according to certain embodiments, is of a substantially cone-like shape with the wide end <NUM> of the cone-like shaped baffle <NUM> at the ring guide light <NUM> and the narrow end <NUM> near the eye of the subject <NUM>. In certain embodiments, as the subject approaches the device, a coaxial light <NUM> becomes visible to aid in coarse alignment of the subject's eye <NUM> with the system. As the subject directs its gaze into the device, some section of the guide light ring <NUM> comes into view. As the subject further adjusts its gaze toward alignment, more and more of the ring <NUM> becomes visible until the entire ring <NUM> is visible indicating that the subject's optical axis <NUM> is in alignment with the to the optical axis of the imaging system <NUM> has been achieved. During this process, the aspect of the ring <NUM> that is not visible will direct the subject to adjust its eye <NUM> in the appropriate direction for alignment. For example, if the right side of the ring <NUM> is fully visible but the left is not, then the subject adjusts its eye <NUM> to the right until the light becomes visible.

According to certain embodiments, best shown in <FIG>, the system is external to the ocular imaging device <NUM> (also referred to as a "camera"). For example, in certain embodiments, the guide lights <NUM> are positioned on a ring <NUM> between the objective lens of the camera <NUM> and the subject's eye <NUM>. According to certain alternative embodiments, best shown in <FIG>, the system is integrated into the ocular imaging device <NUM>. In certain embodiments, the guide lights <NUM> are positioned around the objective lens of the camera <NUM>. In further embodiments, the guide lights <NUM> are positioned within the optics of a fundus camera, or other optical device, in the illumination pathway. In certain embodiments, the guide lights are discretely arranged around the optical opening of an optical imaging device.

According to certain embodiments, best shown in <FIG>, additional direction is provided to the subject by providing a sequence of lights that serve as sequential focal points. By way of example, a first guide light or set of guide lights 4a is activated and the subject aligns its eye <NUM> with the system such that the guide light <NUM> or each of the set of guide lights <NUM> is visible. Next, a second guide light or set of guide lights 4b is activated at a point further down the optical path (more distal from the eye <NUM> of the subject). The second set of guide lights 4b requires a more precise level of alignment in order to become visible to the subject, relative to the first guide light or set of guide lights 4a. In certain embodiments, additional subsequent guide lights are presented to the subject with increasing levels of precision required of the alignment in order for the lights to become visible. As the subject aligns its eye <NUM> with each of the sequential focal points, the subject's eye <NUM> is guided along the z-axis until they are looking at the target ring of light.

In certain embodiments, one or more of the guide lights <NUM> are implemented as collimated light sources such as laser light. In these embodiments, the one or more guide lights <NUM> can be direct along a specific path configured to be visible only when the eye <NUM> is properly positioned. Accordingly, in these implementations, baffles are no longer necessarily needed.

<FIG> show exemplary baffles <NUM>, <NUM> according to certain embodiments. In these embodiments, light emitted from the guide light <NUM> is constrained by a first baffle <NUM> and a second baffle <NUM>. The first baffle <NUM> and second baffle <NUM> define a gap <NUM> through which a guide light beam <NUM> along the alignment path is emitted. As will be appreciated by one skilled in the art, the angle of the baffle(s) <NUM>, <NUM> constrains the light emission such that only a beam <NUM> at the desired beam path angle is emitted, allowing for precise control of the position of the eye required for viewing the masked light. As best shown in <FIG>, baffle angle can be adjusted to produce emission of the alignment beam <NUM> at the desired angle.

In certain alternative embodiments, the one or more guide lights are further comprised of sets of guide lights, wherein each set is configured to achieve alignment with respect to a specific axis (not shown). For example, according to certain embodiments, the plurality of guide lights are further comprised of one or more of z-axis guide lights, configured to be visible when the subject's eye is optimally positioned along the z-axis with respect to the image sensor. The plurality of guide lights are further comprised of one or more x-axis guide lights and one or more y-axis guide lights, configured to be visible to the subject when the subject is optimally positioned and aligned along the x-axis and y-axis, respectively.

According to certain implementations, best shown in <FIG>, each of the one or more guide lights <NUM> is enclosed within a baffle chamber <NUM>. The baffle chamber <NUM> is defined by baffle walls <NUM> and has a first end <NUM>, at which the guide light is positioned, and a second end <NUM>, from which the light is emitted. In certain embodiments, the baffle chamber <NUM> narrows from the first end <NUM> to the second end <NUM>, and in certain embodiments, forms a substantially cone-like shape. In certain implementations, light is emitted from the second end <NUM> through a baffle chamber slit <NUM>. The baffle chamber slit <NUM> ensures that only light that leaves the baffle chamber <NUM> is traveling at the proper angle to achieve alignment with the subjects eye (not shown). According to certain embodiments, the baffle chamber walls <NUM> are comprised of an anti-reflective material, thus further ensuring that only light at the proper angle leaves the baffle chamber <NUM>. In further embodiments, air pockets or voids within the baffle chamber <NUM> are employed to further minimize reflection. According to certain embodiments, best shown in <FIG>, the According to certain embodiments, best shown in <FIG>, the baffle slits <NUM> are angled toward the center of the optical path <NUM>. In certain implementations, the baffle chamber is a guide light assembly, a described elsewhere herein.

In certain implementations, best shown in <FIG>, there are multiple baffle chambers <NUM>. In this specific example, there are three baffle chambers <NUM>. The guide lights <NUM> are disposed within the baffle chambers <NUM> and the baffle chambers <NUM> are mounted on a housing <NUM> configured to interface with an optical imaging device <NUM>. According to certain embodiments, the baffle chambers <NUM> are pivotally mounted on the housing <NUM>, such as by way of a hinge <NUM>. In these embodiments, the angle of the baffle chamber <NUM>, and thus the angle of the emitted guide light beam <NUM>, is adjusted according to the desired ocular alignment point <NUM>. According to certain implementations, the pivotal movement of the baffle chambers <NUM> around their hinges <NUM> is driven by an electric motor or the like so that the baffle chambers <NUM> can be pivoted according to predetermined angles corresponding with various desired points of alignment.

According to further embodiments, best shown in <FIG>, disclosed is an alignment device <NUM> for aligning the eye <NUM> of a subject with an ocular imaging device (not shown). In these implementations the alignment device <NUM> comprises a housing <NUM> with a first end <NUM>, a second end <NUM>, an outer surface <NUM>, and an inner surface <NUM> (as best shown in <FIG>). The housing <NUM> first end <NUM> is configured to interface with an ocular imaging device (such as, for example, a device similar to the device <NUM> embodiments shown in <FIG> and <FIG>) while the second end <NUM> is proximal to the eye <NUM> of the subject. According to certain implementations as best shown in <FIG> and <FIG>, the housing <NUM> is a substantially tubular shape defining a luminal space <NUM> defined by its inner surface <NUM> through which the optical path <NUM> (as shown in <FIG>) between the optical imaging device and the eye <NUM> of the subject can pass. As best shown in <FIG> and <FIG>, a plurality of guide light assemblies <NUM> is arranged on the housing <NUM>.

As best shown in <FIG>, the guide light assemblies <NUM> comprise a body <NUM> having a first side <NUM> extending from the housing outer surface <NUM> and a second side <NUM> facing the luminal space <NUM>. In certain implementations, also best shown in <FIG>, the guide light assemblies <NUM> are slidably mounted into the housing <NUM> such that the user can adjust the position of the guide light assembly <NUM> along a longitudinal axis <NUM>.

As best shown in <FIG> and <FIG>, the guide light assembly body <NUM> defines a channel <NUM> extending from the guide light assembly body first side <NUM> to the second side <NUM> as best shown via the longitudinal axis depicted schematically via line A in <FIG>. The channel forms a first opening 88a on guide light assembly body first side <NUM> and a second opening 88b guide light assembly body second side <NUM>. Disposed within the channel <NUM> is a guide light bezel <NUM> and a guide light <NUM> disposed within the guide light bezel <NUM> (best shown in <FIG>). As best shown in <FIG> and <FIG>, the guide light bezel <NUM> is disposed partially within the channel <NUM> such that a portion of the bezel <NUM> extends out of the channel <NUM> on the first side <NUM>. In certain implementations, the guide light assembly may further comprise a power supply, housed within the body (not shown).

Continuing with <FIG> and <FIG>, the guide light assembly <NUM> further comprises a baffle <NUM> positioned in the channel <NUM> at or near the second channel opening 88b on the second side <NUM> (disposed between the guide light <NUM> and the second channel opening 88b). As shown, the baffle <NUM> is positioned such that it is transverse to the longitudinal axis of the channel <NUM>. The baffle <NUM> has a slit <NUM> defined in the baffle <NUM> that is positioned longitudinally along the length of the baffle <NUM>. In use, the baffle <NUM> occludes rays emitted by the guide light <NUM>, while the slit <NUM> permits passage of rays traveling along the alignment path <NUM> (best shown in <FIG>).

According to certain embodiments, the device further comprises a plurality of secondary baffle assemblies <NUM> (best shown in <FIG> and <FIG>). According to certain embodiments, the plurality of secondary baffle assemblies <NUM> is arranged on the second end <NUM> of the housing <NUM> such that the baffle assemblies <NUM> extend inward toward the center of the luminal space <NUM>, as best shown in <FIG>. In certain implementations, as best shown in <FIG>, the secondary baffle assemblies <NUM> are slidably mounted into the housing <NUM> such that the user can adjust the position of the secondary baffle assembly <NUM> along a longitudinal axis <NUM>. As best shown in <FIG> and <FIG>, each of the secondary baffle assemblies <NUM> further comprise a baffle plate <NUM> and a baffle wall <NUM> extending into the luminal space <NUM>, as mentioned above. The baffle plate <NUM> further comprises a slit <NUM>.

As best shown in <FIG>, light <NUM> emitted from the slit (not shown) in the baffle <NUM> is further masked by the secondary baffle assembly <NUM>, with the baffle plate <NUM> and the baffle wall <NUM> blocking light <NUM> not along the alignment path. The slit <NUM> mentioned above is configured to allow passage of guide light rays <NUM> along the path of alignment. As will be appreciated by a person having skill in the art, adjustment of the guide light assembly or the secondary baffle assembly <NUM> along the longitudinal axis <NUM> permits the adjustment of the angle at which the guide light rays <NUM> are emitted and masked. Such adjustment makes it possible to modify the alignment points with respect to the eye of the subject <NUM>.

According to certain embodiments, the baffle slit <NUM> and the secondary baffle assembly <NUM> slit <NUM> have a generally perpendicular orientation with respect to one another. <FIG> shows a schematic representation of the effect of slit orientation on light masking. As shown in that figure, rays <NUM> are emitted along the length of the baffle slit <NUM>. The secondary baffle assembly <NUM> masks all rays <NUM> except for ray at the proper alignment path <NUM> which passes through the secondary baffle assembly slit <NUM> and is perceptible to the subject's eye <NUM>, indicating proper alignment.

The disclosed devices and systems are capable of imaging multiple ocular regions. In certain embodiments, proper alignment is achieved when the subject's eye is aligned for imaging of the retina. In further embodiments, proper alignment is achieved when the subject's eye is aligned for imaging the cornea. In still further embodiment, proper alignment is achieved when the subject's eye is aligned for imaging the iris. In yet further embodiments, proper alignment is achieved when the subject's eye is aligned for imaging the lens. In further embodiments, proper alignment is achieved when the subject's eye is aligned for imaging the optic nerve head.

As will be appreciated by a person having skill in the art, the disclosed systems and devices can be used with numerous optical imaging systems. In certain embodiments, the optical imaging device is a fundus camera. In further embodiments, the camera is an optical coherence tomography (OCT) retinal camera. In still further embodiments, the optical imaging device is an autorefractor. In yet further embodiments, the optical imaging device is a corneal camera. As will be appreciated by one skilled in the art, other camera types are possible.

According to certain embodiments, the system further comprises one or more indicator signals. In these embodiments, each indicator signal serves to provide additional guidance to the subject regarding the required direction of eye movement to achieve alignment. Example indicator signals include, but are not limited to, arrows, colors, or flashing lights. In certain implementations, sounds and/or other non-visual feedback cues are also possible. According to certain embodiments, the indicator signals are masked by one or more baffles such that they are only visible when the eye is out of alignment. For example, a rightward pointing arrow indicator signal is baffled such that it is only visible to the subject when the subject eye is directed to the left of proper alignment.

According to certain embodiments, , indicator signals are comprised of colored ring lights of differing colors (not shown). The one or more guide lights is a color different from the colors of the one or more indicator signal. <FIG> shows an eye of a subject <NUM> out of alignment where the subject is able to view a red indicator signal light <NUM> but unable to see the green guide light <NUM>. Similarly, if the subject is able to view the yellow indicator signal <NUM>, its eye <NUM> is not in proper alignment. <FIG> shows an eye of a subject in proper alignment where the subject is able to see the green guide light <NUM> but unable to see the yellow <NUM> or red indicator signals <NUM>. According to certain embodiments, (not shown) the indicator signal the subject is able to view conveys information to the subject about the direction the eye needs to adjust in order to achieve proper alignment.

Claim 1:
A device for aligning a subject's eye with an optical axis of an ocular imaging device comprising:
a. a housing comprising a first end, a second end, an outer surface, and an inner surface, wherein the inner surface defines a luminal space and wherein the luminal space is configured to allow for passage of the optical axis therethrough;
b. a plurality of guide light assemblies disposed within the housing, each guide light assembly comprising:
i. a body comprising a first side and a second side opposite the first side, wherein the second side faces the luminal space;
ii. a channel defined in the body, wherein the channel extends from the body first side to the body second side, wherein the channel forms an opening in the body second side;
iii. a guide light disposed within the channel, wherein the guide light is configured to emit light out of the opening; and
iv. a baffle disposed transversely in the channel between the guide light and the opening and configured to mask light from the guide light, wherein the baffle further comprises a slit configured to allow passage of light along a path of ocular alignment; and
c. a plurality of secondary baffle assemblies disposed on the housing second end, wherein each of the plurality of second baffle assemblies is configured to mask light emitted from one of the plurality of guide light assemblies, wherein each of secondary baffle assemblies further comprises a slit configured to allow passage of light along a second path of ocular alignment,
wherein the light from each of the plurality of guide light assemblies is visible to the subject when the subject's eye is in alignment with respect to the optical axis of the ocular imaging device and not visible when the subject's eye is out of alignment with respect to the optical axis of the ocular imaging device.