Functional retinal imaging with adaptive stimuli

Abstract

A technique and apparatus for performing a visual field test on an eye includes sequentially presenting visual stimuli to the eye on a display. A first fixation target is presented on display in a first position offset from a center of the display, such as while presenting first visual stimuli on the display for measuring a visual function sensitivity of the eye contemporaneously with presenting the first fixation target. A response of the eye to the first visual stimuli is registered. A second fixation target is presented on the display in a second position offset from the center of the display, wherein the second position is different than the first position, such as while presenting second visual stimuli on the display for measuring a visual function sensitivity of the eye contemporaneously with presenting the second fixation target. A response of the eye to the second visual stimuli is registered.

Description

FUNCTIONAL RETINAL IMAGING WITH ADAPTIVE STIMULICROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of US Provisional Application No.63 / 721,757, filed Nov. 18, 2024, the contents of which are hereby incorporated by reference.TECHNICAL FIELD

[0002] This disclosure relates generally to ophthalmology devices, and in particular but not exclusively, relates to visual field testing.BACKGROUND INFORMATION

[0003] Visual field testing is an important tool in the field of ophthalmology. Conventional visual field testing can take 10-30 minutes vs. 10-30 seconds for optical coherence tomography (OCT) or fundus imaging. One major reason for this length is due to inaccuracies in conventional testing techniques. The Humphrey Visual Field Analyzer is one such tool currently available for performing a visual field test.

[0004] Accurate visual field testing is essential for tracking the progression of many neurological diseases including Glaucoma. The test involves asking a patient to maintain their gaze on a fixation target while presenting stimuli to different parts of the retina (i.e., different parts of their field of view) and recording acknowledgement responses of the patient in the form of seen / not seen as registered by pushing a button. Maintaining a stable fixation is important in order to identify which portion of the retina is being stimulated by a particular visual stimulus. The Humphrey Visual Field Analyzer operates in this manner.

[0005] However, the standard test is not without its limitations. Firstly, the subjective nature of user input based on perceived stimuli presents a challenge. Secondly, certain patients face the inability to maintain stable fixation throughout the test, either due to fixation drifts caused by microsaccades or inherent ocular diseases resulting in unstable fixation. Consequently, the intra-subject test-retest variability remains relatively high, posing significant challenges in effectively tracking disease progression. Furthermore, it is widely believed that a significant proportion of the variability observed in glaucoma patients stems primarily from fixation inaccuracies.13960-P403WOBRIEF DESCRIPTION OF THE DRAWINGS

[0006] Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. Not all instances of an element are necessarily labeled so as not to clutter the drawings where appropriate. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles being described.

[0007] FIGS. 1 A-1F illustrate a fixation target and a display that sequentially presents visual stimuli to an eye during a visual field test, in accordance with an embodiment of the disclosure.

[0008] FIG. 2A and 2B illustrate two demonstrative types of visual function sensitivity maps, in accordance with an embodiment of the disclosure.

[0009] FIG. 3 is a functional block diagram illustrating components of an ophthalmic testing system for performing ophthalmic testing including visual field testing and retinal imaging, in accordance with an embodiment of the disclosure.

[0010] FIG. 4 is a flow chart illustrating a process of operating the ophthalmic testing system while performing a visual field test, in accordance with an embodiment of the disclosure.

[0011] FIG. 5 A illustrates an eye having a gaze direction that remains fixated on a fixation target while a visual stimulus is presented on a display, in accordance with an embodiment of the disclosure.

[0012] FIG. 5B illustrates an eye having a gaze direction that has drifted from the fixation target while a visual stimulus is presented on a display, in accordance with an embodiment of the disclosure.

[0013] FIG. 5C illustrates a gaze location of an eye gaze on a display and a visual stimulus location on the display, in accordance with an embodiment of the disclosure.

[0014] FIG. 5D. illustrates a gaze location including a drifted fixation and a stimulus location and an adjusted stimulus location, in accordance with an embodiment of the disclosure.

[0015] FIG. 6 is an example optical implementation of the ophthalmic testing system described in FIG. 3, in accordance with an embodiment of the disclosure.23960-P403WO

[0016] FIG. 7 is a functional block diagram of a retinal camera including an integrated image signal processor, in accordance with an embodiment of the disclosure.

[0017] FIG. 8 is a block flow diagram illustrating image processing by a retinal camera including an integrated image signal processor, in accordance with an embodiment of the disclosure.

[0018] FIG. 9 illustrates pupil size as a function of time and functions fit to the pupil size, in accordance with an embodiment of the disclosure.

[0019] FIG. 10A illustrates pupil size as a function of time in response to periodic stimulation, in accordance with an embodiment of the present disclosure.

[0020] FIG. 10B illustrates the pupil diameter as a function of time from FIG. 10A with a baseline subtracted from the pupil diameter, in accordance with an embodiment of the disclosure.

[0021] FIG. 10C illustrates a power spectrum of the baseline-corrected pupil diameter as a function of time from FIG. 10B, in accordance with an embodiment of the present disclosure.DETAILED DESCRIPTION

[0022] Embodiments of a system, apparatus, and method of operation for performing functional retinal imaging with adaptive stimuli and extended field of view that facilitate a visual field test and obtain high quality retinal images are described herein. In the following description numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects.

[0023] Reference throughout this specification to “one embodiment" or “an embodiment7’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.33960-P403WO

[0024] FIGS. 1A-1F illustrate a fixation target 105 and a display 110 that sequentially presents visual stimuli 115A-115L (collectively 115) to an eye 120 at times T1-T12, respectively, during a visual field test, in accordance with an embodiment of the disclosure. The user is asked to maintain their gaze direction 125 towards fixation target 105. A response to the visual stimuli 115 is registered or measured. Visual stimuli 115 are sequentially presented to the user throughout display 110 to measure a visual function sensitivity of eye 120 over the field of view (FOV) of the eye 120. The user inputs and / or responses of the eye 120 to the stimuli 115 are collected and analyzed to generate a visual function sensitivity map, such as a composite visual function sensitivity' map.

[0025] In FIGS. 1 A and IB, the fixation target 105 is positioned at a center 131 of the display 110. As discussed further herein, and as illustrated in FIGS. 1C-1F, in certain embodiments, the fixation target 105 is presented at positions away from or offset from a center 131 of the display 110. As also discussed further herein, by¬ presenting the fixation target 105 offset from a center 131 of the display 110, a FOV and an assayed portion of the eye 120 is expanded. For example, in an embodiment, when the fixation target 105 is in the center 131 of the display 110, the maximum FOV is limited to ~50°x36°. However, where the fixation target 105 is offset from a center 131 of the display 110, such as toward comers of the display 110. and measured, for example, a quadrant at a time, the maximum FOV is extended to ±30°.

[0026] In this regard, FIGS. 1C-1F show' the fixation target 105 sequentially positioned in different quadrants 145, 150, 155, and 160 of the display 110, while contemporaneously displaying visual stimulus 115. While quadrants 145, 150, 155, and 160 of the display 110 are discussed, it will be understood that the display 110 can be divided according to many different schemes, which are within the scope of the present disclosure. In this regard, the display 110 can be divided into two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, and ten or more sections into which the fixation target 105 is displayed, such as while visual stimuli 115 are contemporaneously displayed a response of an eye 120 to the visual stimuli 115 is measured or recorded.

[0027] FIGS. 2A and 2B illustrate tw o demonstrative types of visual function sensitivity maps, in accordance with an embodiment of the disclosure. The first visual function sensitivity map is a numerical map in FIG. 2A, which presents a grid of numbers that spatially indicate the sensitivity of the user’s retina responses during the 43960-P403WOvisual field testing. The numbers are indicative of the sensitivity of the retina at a given spatial location. The second visual function sensitivity map is a heat map in FIG. 2B, which presents similar data as the numerical map, but graphically rather than numerically. It is noted that FIG. 2A is a time-domain measurement, with pupil size change amplitude is used as a sensitivity7, whereas FIG. 2B is a frequency -domain measurement, with pupil oscillation spectral power used as sensitivity7. It will be understood that the frequency-domain analysis can be plotted as in FIG. 2A, and timedomain analysis can be plotted as FIG. 2B. Other forms of visual function sensitivity maps may be generated based upon the user inputs or measurements registered during the visual field testing.

[0028] Returning to FIGs 1A and IB, embodiments disclosed herein use camera 130 to monitor gaze direction 125 to identify when gaze direction 125 has drifted from fixation target 105. When gaze direction 125 is determined to have drifted during presentation of a given one of visual stimuli 115, an intended position associated with the given visual stimulus 115 is offset so that the user inputs are registered and used. In other words, intended positions associated with visual stimuli 115 are offset to compensate for a drifting gaze direction 125 instead of rejecting the user inputs or measured responses of the eye 120 to the stimuli 115. These offset intended positions can then be used when generating visual function sensitivity maps, thereby reducing the overall time of the visual field test. By reducing the overall length of the visual field test, eye 120 is less likely to fatigue, thereby reducing the likelihood gaze direction 125 will drift in the first place. In one embodiment, camera 130 is a retinal camera that tracks gaze direction in real-time by tracking anatomical features of retina 121.

[0029] FIG. 3 is a functional block diagram illustrating components of an ophthalmic testing system 300 for performing ophthalmic testing including visual field testing and retinal imaging, in accordance w ith an embodiment of the disclosure. The illustrated embodiment of system 300 includes a controller 305, a retinal camera 310, an pupil camera315, adisplay 110, an infrared (IR) illuminator 325, a flash illuminator 330, and memory 340.

[0030] As mentioned above, display 110 operates as a visual field display to sequentially present visual stimuli 115 to eye 120. In one embodiment, display 110 is a micro-display (e.g., a liquid crystal display, organic light emitting diode display, a liquid crystal on silicon display, a light emitting diode array, etc.). In one embodiment,53960-P403WOdisplay 110 also presents fixation target 105 as a stationary element during visual field testing.

[0031] Pupil camera 315 is included to provide gross gaze tracking and blink detection. For example, pupil camera 315 may be focused on external portions of the eye, such as the iris 317 or pupil 319. In contrast, retinal camera 310 is configured to focus on retina 121 on the interior of eye 120 through pupil 319. Retinal camera 310 is operated to provide high-speed, high-precision gaze tracking (i.e.. monitoring of gaze direction 125) by imaging and tracking anatomical features, such as feature 320, on retina 121. While conventional pupil tracking cameras are capable of gaze tracking within tolerances measured in degrees (e.g., within 3 degrees), retinal tracking by retinal camera 310 is capable of gaze tracking within tolerances measured in millidegrees. These improved tolerances reduce image noise. In some embodiments, retinal camera 310 can also serve to produce high quality retinal or fundus images, in addition to, gaze tracking based on anatomical features.

[0032] IR illuminator 325 is provided to illuminate retina 121 and / or iris 317 with IR or far-IR illumination during gaze tracking. In one embodiment. IR illumination is output by IR illuminator 325 continuously during visual field examination to provide continuous real-time gross gaze direction monitoring and blink detection. Flash illuminator 330 provides visual spectrum, flash illumination when retinal camera 310 is acquiring retinal images. In one embodiment, the fine gaze detection performed by retinal camera 310 uses a series of high-speed retinal images, each acquired with flash illumination. In an embodiment, the flash illuminator 330 emits IR illumination and IR images, such as rather than color images, of the fundus are used for gaze tracking. In one embodiment, flash illuminator 330 outputs a white light flash. IR illuminator 325 and / or flash illuminator 330 may be implemented using one or more light emitting diodes (LEDs).

[0033] User interface 335 provides a user feedback mechanism for registering user inputs indicating whether the user acknowledges observance of visual stimuli 115 presented on display 110. In one embodiment, user interface 335 may be a simple button or mechanical clicker. In other embodiments, user interface 335 may be a microphone for registering voice prompts. Other user interfaces may be implemented. While a user interface 335 is described, it will be understood that a response to visual stimuli 115 can be registered or measured in other ways, such as by measuring or registering a change in pupil size in response to visual stimuli 115, as discussed further 63960-P403WOherein with respect to FIGS. 9 and 10. In an embodiment, user interface 335 is optional.

[0034] Controller 305 is coupled to the other components of system 300 to choreograph their operation for performing visual field tests and / or obtaining retinal or fundus images. Controller 305 may include a microprocessor for executing software / firmware instructions stored on memory 340. Controller 305 may include hardware logic (e.g., application specific integrated circuit, field programmable gate array, logic gates, etc.) for implementing the functionality described herein. In some embodiments, controller 305 acquires retinal images of retina 121 from retinal camera 310 and transfers those retinal images into memory 340 for storage and / or subsequent image processing.

[0035] FIG. 4 is a flow chart illustrating a process 400 of operation of ophthalmic testing system 300 while performing a visual field test, in accordance with an embodiment of the disclosure. Process 400 is described with reference to FIGS.1A-1F and 5 A and 5B. The order in which some or all of the process blocks appear in process 400 should not be deemed limiting. Rather, one of ordinary skill in the art having the benefit of the present disclosure will understand that some of the process blocks may be executed in a variety of orders not illustrated, contemporaneously, or even in parallel.

[0036] With fixation target 105 presented offset from the center 131 of display 110, in a process block 402, controller 305 operates display 110 to present a first visual stimulus 115A to eye 120 in process block 405. Visual stimulus 115A may assume a variety of different shapes, colors, and patterns; however, in one embodiment, visual stimulus 115A is a monochromatic dot (e.g., red dot, black dot, etc.). In an embodiment, white stimuli 115 are shown on a scotopic, mesopic or photopic background. Chromatic stimuli 115 can also be used depending on different applications. Intensities, dimensions and exact locations of the stimuli 115 are variable and programmable. One stimulus 115 is presented at a time. Typical duration of the stimulus 115 pulse can be. for example, from 10 ms to 1 sec. In an embodiment, intervals between two consecutive stimuli 115 can be between 3 sec and 10 sec. In an embodiment, positions of the stimuli 115 on the display 110 are randomized. During the entire test, the subject is instructed to fixate at the fixation target 105 as it is variously positioned on the display 110.73960-P403WO

[0037] Contemporaneously with presenting visual stimulus 115A (and in some embodiments includes prior to presenting visual stimulus 115A), controller 305 uses retinal camera 310 to track gaze direction 125 of eye 120. Retinal camera 310 is focused on retina 121 of eye 120 and uses anatomical features of retina 121 for monitoring gaze direction 125 in real-time. In one embodiment, retinal camera 310 includes an integrated image signal processor that internally analyzes retinal images and outputs gaze tracking data in real-time to controller 305. Controller 305 then uses the gaze tracking data, as opposed to the retinal images themselves, to determine whether eye 120 is fixated on fixation target 105.

[0038] If gaze direction 125 of eye 120 is determined to be aligned with fixation target 105 within an acceptable threshold (decision block 415; see FIG. 5A), then process 400 continues to process block 435 where the user’s input indicating whether they saw or didn’t see visual stimulus 115A is registered. However, if controller 305 determines that gaze direction 125 of eye 120 has drifted away from fixation target 105 during presentation of visual stimulus 115A (decision block 415; see FIG. 5B). then process 400 continues to general process block 420 to offset an intended position associated with visual stimulus 115 A and compensate for the drifting of gaze direction 125 from fixation target 105 during presentation of visual stimulus 115A.

[0039] General process block 420 can be implemented by either one of process block 425 or process block 430. In process block 425, the intended position associated with visual stimulus 115A is an intended display position 515A. When gaze direction 125 is fixated on fixation target 105 (see FIG. 5A), display position 515B (which is physically the same as intended display position 515 A in FIG. 5B) stimulates retinal position 520A and operates as a visual function sensitivity test of retinal position 520A. However, since gaze direction 125 has drifted or strayed from fixation target 105 (see FIG. 5B), intended display position 515 A no longer stimulates intended retinal position 520B (which is the same physical location on retina 121 as retinal position 520A). Rather, intended display position 515 A ends up stimulating a different portion of retina 121, thereby spoiling the visual field test results, unless the gaze drifting is compensated. Accordingly, in process block 425, intended display position 515A is offset, or physically shifted on display 110, to offset display position 525 by an amount and a direction (i.e., vector offset) that causes visual stimulus 115A (as offset in FIG. 5B) to stimulate intended retinal position 520B on retina 121. Intended 83960-P403WOretinal position 520B is equivalent to retinal position 520A, which is stimulated by display position 515B (see FIG. 5A) when gaze direction 125 is aligned with fixation target 105. Accordingly, process block 425 offsets the position of visual stimulus 115A by a vector offset that compensates for the drifting of gaze direction 125.

[0040] Optionally, process block 430 may be executed to offset an intended position associated with visual stimulus 115A to compensate for drifting of gaze direction 125 from fixation target 105 during presentation of visual stimulus 115 A. In process block 430, the intended position associated with visual stimulus 115A is intended retinal position 520B on retina 121, which would be stimulated if gaze direction 125 was aligned with fixation target 105, as illustrated in FIG. 5A. Accordingly, instead of offsetting the physical position of visual stimulus 115 A on display 110, intended retinal position 520B is mapped to offset retinal position 530 that is actually stimulated by visual stimulus 115 A in its intended display position 515A. Accordingly, general process block 420 offsets an intended position associated with visual stimulus 115A to compensate for drifting of gaze direction 125 by either shifting the physical position of visual stimulus 115A on display 110 in real-time based upon gaze tracking data from retinal camera 310, or remaps the intended retinal position 520B being tested to an offset retinal position 530 based upon the gaze tracking data from retinal camera 310.

[0041] In some cases, the user’s gaze direction 125 may drift or scan in multiple different directions during the presentation of a single visual stimulus 115A. Accordingly, in some embodiments, the mapping of a given visual stimulus is time weighted across multiple offset intended positions on retina 121, when gaze direction 125 is determined to have moved during presentation of a given visual stimulus. Accordingly, the user’s input associated with a given visual stimulus 115 may be time weighted and mapped to multiple offset intended positions (e.g., multiple offset retinal positions).

[0042] With the intended position associated with visual stimulus 115A is offset to compensate for drifting of gaze direction 125, a response to the visual stimulus 115A is registered (process block 435). In this manner, the visual field testing technique of process 400 does not reject user inputs acquired when the user’s gaze direction 125 has drifted off of fixation target 105, but rather offsets and compensates for this gaze drifting.93960-P403WO

[0043] While fixation targets, such as fixation target 105, in FIGS. 5A-5D are illustrated in a center of the display, it will be understood that fixation targets can be illustrated offset from a center of the display, as illustrated and discussed further herein with respect to FIGS. 1C-1F, and that methods of correcting for drifted gaze and possible with such offset fixation targets.

[0044] The visual field testing of process 400 continues to loop by updating the location of the next visual stimulus 115B, C... , and the offset position of the fixation target 105 (process block 445) to test the visual function sensitivity of eye 120 over the user’s FOV by testing a variety' of different locations throughout retina 121.

[0045] In this regard, not only is the visual stimulus 115 position changed, so too, in certain embodiments, is the fixation target 105 position. Accordingly, in an embodiment, a first fixation target 105 A is presented on the display 110 in a first position 135 offset from a center 131 of the display 110, such as in FIG. 1C, while presenting first visual stimuli 115A-115C on the display 110 at times T1-T3, respectively, for measuring a visual function sensitivity of the eye 120 contemporaneously with presenting the first fixation target 105 A. A response of the eye 120 to the first visual stimuli 115A-115C is registered. Additionally and separately, a second fixation target 105B is presented on the display 110 in a second position 140 offset from the center 131 of the display 110. As shown, the second position 140 is different than the first position 135. Second visual stimuli 115D-115F are presented on the display 110, such as at times T4-T6, respectively, for measuring a visual function sensitivity' of the eye 120 contemporaneously with presenting the second fixation target 105B. and a response of the eye 120 to the second visual stimuli 115D-115F is registered or otherwise measured.

[0046] Fixation targets 105A-105D are sequentially presented offset from the center 131 of the display 110 at different positions within the display 110, such as broken up by quadrant or other spatial dividing schemes, while visual stimuli 115 are also presented on the display 110. In an embodiment, the first portion 135 is disposed in a first quadrant 145 of the display 110 and the second portion 140 is disposed in a second quadrant 150 of the display 110 different than the first quadrant 145. In such embodiments, generating the composite visual function sensitivity map of the eye 120 is based on registered responses of the eye 120 to visual stimuli 115A-115L with fixation targets 105A-105D presented in all quadrants 145, 150. 155, and 160 of the display 110 over corresponding times T1-T12.103960-P403WO

[0047] In an embodiment, registering the response of the eye to the first visual stimuli 115A-115C or the second visual stimuli 115D-115F comprises registering user inputs indicating whether the user acknowledges observance of each of the visual stimuli 115 presented, such as with user interface 335.

[0048] In an embodiment, registering the response of the eye 120 to the first visual stimuli 115A-115C or the second visual stimuli 115D-115F comprises measuring with the camera 130 a size of a pupil of the eye 120 in response to the first visual stimuli 115A-115C or the second visual stimuli 115D-115F, such as measuring a size of the pupil as a function of time. In an embodiment, this comprises measuring, with the camera 130, temporal changes in pupil diameter in response to visual stimuli 115 at a particular position on the display 110.

[0049] In an embodiment, raw data of pupil radius associated with timestamps is processed to reject blinks and other artifacts. In an embodiment, a trendline of baseline pupil size is obtained. Pupil radius can be normalized to the baseline. Blinks can also cause pupil size change, or a blink-locked pupillary response. These blink-related size changes can have similar amplitudes and profiles with those from hght-stimulated pupillary response. The blink-induced pupil size changes can be considered to be artifacted and may contaminate the data of interest. In an embodiment, multiple tests are repeated to ensure there is good quality data for each stimulus. In an embodiment, guided or timed blinks are encouraged.

[0050] In an embodiment, measuring, such as with the camera 130, a size change of a pupil of the eye 120 in response to the first visual stimuli 115A-115C or the second visual stimuli 115D-115F comprises fitting the light-induced pupillary response with a log-normal function, such as a log-normal function according to the following formula:

[0052] where A is the amplitude of the constriction peak, tp is the time delay to from stimulus 115 onset to the maximum constriction, and <7 defines the shape of the constriction profile. In an embodiment, log-normal fitting is performed on each light-induced concentration to extract these parameters. See FIG. 9.113960-P403WO

[0053] In an embodiment, after multiple retests (e.g., N=3), the mean and standard deviation of the pupillary light reflex at each retina location are calculated and included in the composite visual function sensitivity map. See FIG. 2A.

[0054] Unlike transient pupillary light reflex, when the stimulus 115 is flickering or otherwise periodically presented at a fixed frequency, the pupil may not have enough time to recover to the baseline size after initial size change. In this case, the pupillary responses show an oscillation profile. Frequency domain analysis can be carried out to identify the oscillation frequency and the power spectral after Fast Fourier Transform. In the power spectrum, the sharpest peak is the oscillation frequency. See FIG. 10C. Accordingly, in an embodiment, methods according to the present disclosure comprise presenting with the display 110 the first visual stimuli 115A-115C or the second visual stimuli 115D-115F at a visual stimulation frequency. Pupil diameter is measured, such as with the camera 130, in response to the first visual stimuli 115A-115C or the second visual stimuli 115D-115F as function of time. See for example FIG. 10A. A pupil diameter baseline is subtracted from the measured pupil diameter. See for example FIG. 10B. A pupil contraction frequency is identified, such as through Fast Fourier Transform analysis. See for example FIG. 10C.

[0055] An advantage of frequency-domain flickering or periodic stimulation is that there are fewer impacts due to the blinks or other artifacts. The spectral power at the oscillation frequency can be a metric used to evaluate the functional sensitivity within the visual field.

[0056] In embodiments where visual stimuli 115 are presented a visual stimulation frequency and a pupil contraction frequency is identified, registering the response of the eye 120 to the first visual stimuli 115A-115C or the second visual stimuli 115D-115F is based on the pupil contraction frequency.

[0057] Once retina 121 has been adequately tested over the user’s FOV, the visual field test is completed (decision block 440) and a composite visual function sensitivity map (e.g.. numerical map 205, heat map 210, etc.) is generated for doctor / patient review.

[0058] In an embodiment, generating a composite visual function sensitivity map of the eye 120 is based on the registered and / or measured responses of the eye 120 to visual stimuli 115, such as the first visual stimuli 115A-115C or the second visual stimuli 115D-115F, where the fixation target 105 is displayed in various portions of the display 110 offset from the center 131 of the display 110.123960-P403WO

[0059] The composite visual function sensitivity maps generated by process 400 are generated using registered and / or measured responses of the eye 120 to visual stimuli 115, both while gaze direction 125 was fixated on fixation target 105 (e.g., FIGS. 5A and 5C) and while gaze direction 125 drifted from fixation target 105 (e.g., FIG. 5B and 5D). Since inputs acquired while gaze direction 125 has drifted are used, the visual field test of process 400 reduces the testing time compared to conventional visual field tests.

[0060] FIG. 6 is an example ophthalmic testing system 600, in accordance with an embodiment of the disclosure. System 600 is one possible optical implementation of ophthalmic testing system 300 described and illustrated in FIG. 3. The illustrated embodiment of system 600 includes controller 305, retinal camera 310, pupil camera 315, display 110, an annular illuminator 605, memory 340 (not illustrated in FIG. 6), alignment mirror 610, hole mirror 615, beam splitter 620, and lenses 625. The illustrated embodiment of hole mirror 615 includes a central section 630 and a peripheral section 635. Annular illuminator 605 incorporates the functionality provided by both IR illuminator 325 and flash illuminator 330. System 600 operates in the same manner as system 300 as described in connection with FIGS. 3 and 4 to perform a visual field test.

[0061] Central section 630 of hole mirror 615 is substantially transmissive to visible light and aligned to pass retinal images of retinal 121 within eye 120 to retinal camera 310. In contrast, peripheral section 635 is substantially reflective to IR light and reflects IR iris images from eye 120 to pupil camera 315 and reflects IR light from annular shaped illuminator 605 to eye 120. In one embodiment, peripheral section 635 is substantially reflective to both IR light and visible light to reflect white light flashed from annular illuminator 605 into eye 120 for acquiring retinal images of retina 121. The retinal images are then passed through central section 630 to retinal camera 310. In one embodiment, central section 630 is coated with one or more optical films (e.g., dichroic coatings) to substantially pass light with wavelengths below 900 nm while substantially reflecting light above 900 nm. Hole mirror 615 serves to reduce ghost images from annular illuminator 605 from reaching retinal camera 310. In one embodiment, pupils camera 315 is disposed in a center of annular illuminator 605, which has an annular shape. As discussed above, pupil camera 315 operates to track gross movements of eye 120, such as blinking and gross gaze tracking, by tracking or imaging the iris and / or pupil of eye 120.133960-P403WO

[0062] Beam spliter 620 is positioned to pass a portion of the light of retinal images to retinal camera 310 while reflecting display light including fixation target 105 and visual stimuli 115 to eye 120. In some embodiments, beam spliter 620 is more transmissive than reflective. In one embodiment, beam spliter 620 is approximately 90% transmissive and 10% reflective. Other reflectance / transmitance ratios may be implemented. Alignment mirror 610 is provided to align eye 120 into the optical system. In the illustrated embodiment, alignment mirror 610 is coupled to controller 305 to provide auto-alignment. In other embodiments, alignment mirror 610 may be manually adjusted (e.g., pivoted) as an initial setup. Lenses 625 are provided throughout system 600 to provide image and light focusing in the optical paths.

[0063] FIG. 7 is a functional block diagram of a retinal camera 700 including an integrated image signal processor, in accordance with an embodiment of the disclosure. Retinal camera 700 is one possible implementation of retinal camera 310. The illustrated embodiment of retinal camera 700 includes a two-dimensional sensor array 705, data conversion circuitry 710. a memory buffer 715. an integrated image signal processor (ISP) 720, a higher speed output port 725 and a slower speed output port 730.

[0064] During operation, two-dimensional image data (e.g., retinal images) is acquired by sensor array 705 and converted from the analog domain to the digital domain by data conversion circuitry 710. The image data is acquired at a full frame rate (e.g., 30 frames per second) and stored into memory buffer 715. ISP 702 operates on the buffered retinal image frames to generate gaze tracking data and composite or mosaic retinal image data. The gaze tracking data is generated in real-time and output on higher speed output port 725 to controller 305. In one embodiment, the gaze tracking data is output on higher speed output port 725 at the full frame rate (e.g., 30 frames per second). In one embodiment, the gaze tracking data is output at a substantially higher rate than the inverse of the duration of a given visual stimulus. For example, in one embodiment, gaze tracking data is refreshed and output on higher speed output port 725 at or above 100 Hz. In contrast, the retinal images or mosaic retinal images are output at a reduced speed on slower speed output port 730.

[0065] Using higher speed output port 725 to output gaze tracking data while using slower speed output port 730 for image data enables controller 305 to perform real-time gaze tracking based upon retinal images, while giving retinal camera 700 more time to generate high quality composite or mosaic retinal images.143960-P403WO

[0066] FIG. 8 is a block flow diagram illustrating image processing by retinal camera 700 that leverages the benefits of having the integrated ISP 720 to acquire high qualify mosaic retinal images, in accordance with an embodiment of the disclosure. As illustrated, retinal images 805 A-C are acquired by sensor array 705 at a full frame rate (e.g., 30 frames per second), converted into the digital domain by data conversion circuitry 710, and buffered into memory buffer 715. An image analyzer 810 is executed by ISP 720 to analyze the buffered retinal images 805 (a sort of preprocessing) to determine which of retinal images 805 are of sufficient qualify and which are of insufficient qualify. For example, image analyzer 810 may analyze retinal images 805 for images that are unacceptably blurred, do not have sufficient contrast to be useful, are washed out, and / or include unacceptable comeal reflections. Images that are deemed unacceptable are flagged unacceptable (e.g., marked with a zero bit) while images that are deemed acceptable are flagged as such (e.g., marked with a one bit). The images flagged as unacceptable may be discarded. The images marked as acceptable are registered to each other (e.g., pixel-to-pixel alignment) by image registration module 815, and then combined by mosaicking module 820 into a single mosaic retinal image 825. Mosaicking module 820 may combine images to generate high dynamic range images, to generate larger images having a larger FOV of retina 121 based upon a series of smaller partially overlapping retinal images, or otherwise. For example, in one embodiment, each image acquired may be shifted by just one, two. three, or more pixels both vertically and / or horizontally. By aligning and combining smaller retinal images, each shifted by a few pixels and generated based upon a smaller spot size illuminated through the pupil, into larger mosaic images 825, the likelihood of deleterious comeal reflections due to misalignments are reduced while achieving a high dynamic range. Furthermore, any of retinal image frames 805 spoiled by misalignment are simply flagged, discarded, and not used to generate the larger mosaic retinal image 825. Since mosaic retinal images 825 are output on the slower speed output port 730. ISP 720 is given more time to perform the image processing while still outputting gaze tracking data at the higher speed on higher speed output port 725 to controller 305 for real-time tracking.

[0067] The processes explained above are described in terms of computer software and hardware. The techniques described may constitute machine-executable instructions embodied within a tangible or non-transitory machine (e.g.. computer) readable storage medium, that when executed by a machine will cause the machine to 153960-P403WOperform the operations described. Additionally, the processes may be embodied within hardware, such as an application specific integrated circuit ('’ASIC' J or otherwise.

[0068] A tangible machine-readable storage medium includes any mechanism that provides (i.e., stores) information in anon-transitory form accessible by a machine (e.g., a computer, network device, personal digital assistant, manufacturing tool, any device with a set of one or more processors, etc.). For example, a machine-readable storage medium includes recordable / non-recordable media (e.g., read only memory (ROM), random access memory (RAM), magnetic disk storage media, optical storage media, flash memory devices, etc.).

[0069] The above description of illustrated embodiments of the invention, including what is described in the Abstract, is not intended to be exhaustive or to limit the invention to the precise forms disclosed. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize.

[0070] These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification. Rather, the scope of the invention is to be determined entirely by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.163960-P403WO

Claims

CLAIMSWhat is claimed is:

1. An apparatus for ophthalmic testing, the apparatus comprising: a display for presenting visual stimuli to an eye;a controller coupled to the display, the controller comprising at least one processor and a machine-readable storage medium comprising computer-executable instructions stored thereon that, when executed by the at least one processor, causes the at least one processor to perform operations comprising:presenting a first fixation target on the display in a first position offset from a center of the display:presenting first visual stimuli on the display for measuring a visual function sensitivity of the eye contemporaneously with presenting the first fixation target;registering a response of the eye to the first visual stimuli; presenting a second fixation target on the display in a second position offset from the center of the display, wherein the second position is different than the first position;presenting second visual stimuli on the display for measuring a visual function sensitivity of the eye contemporaneously with presenting the second fixation target;registering a response of the eye to the second visual stimuli; and generating a composite visual function sensitivity map of the eye based on the registered responses of the eye to the first visual stimuli and the second visual stimuli.

2. The apparatus of Claim 1, further comprising a camera positioned to image the eye while the first visual stimuli and the second visual stimuli are presented to the eye.

3. The apparatus of Claim 2. wherein registering the response of the eye to the first visual stimuli or the second visual stimuli comprises measuring with the camera a size of a pupil of the eye in response to the first visual stimuli or the second visual stimuli.173960-P403WO4. The apparatus of Claim 2, wherein the controller is operatively coupled to the camera, and wherein the machine-readable storage medium stores further instructions that, when executed by the controller, causes the at least one processor to perform further operations comprising:measuring, with the camera, temporal changes in pupil diameter in response to visual stimuli at a particular position on the display;wherein generating the composite visual function sensitivity map is based on the measured temporal changes in pupil diameter.

5. The apparatus of Claim 2, wherein the controller is operatively coupled to the camera, and wherein the machine-readable storage medium stores further instructions that, when executed by the controller, causes the at least one processor to perform further operations comprising:presenting, with the display, the first visual stimuli or the second visual stimuli at a visual stimulation frequency;measuring, with the camera, pupil diameter in response to the first visual stimuli or the second visual stimuli as function of time;subtracting a pupil diameter baseline from the measured pupil diameter; and identifying a pupil contraction frequency;wherein registering the response of the eye to the first visual stimuli or the second visual stimuli is based on the pupil contraction frequency.

6. The apparatus of Claim 2, wherein the controller is operatively coupled to the camera, and wherein the machine-readable storage medium stores further instructions that, when executed by the controller, causes the at least one processor to perform further operations comprising:monitoring a gaze direction of the eye with the camera to identify when the gaze direction has drifted from the fixation target;mapping a first intended retinal position on a retina, which is associated with a visual stimulus of the first visual stimuli or the second visual stimuli, to an offset retinal position that is actually stimulated by the visual stimulus due to a drifting of the gaze direction, wherein the mapping compensates for the drifting of the gaze direction from the fixation target when the gaze direction is determined to have drifted during presentation of the visual stimulus, wherein the first intended retinal position is183960-P403WOstimulated by the visual stimulus on the display when the gaze direction is aligned with the fixation target.

7. The apparatus of claim 6, further comprising:an annular shaped illuminator coupled to the controller for illuminating the retina with infrared light while monitoring the gaze direction of the eye.

8. The apparatus of claim 7, further comprising:a pupil camera coupled to the controller and disposed in a center of the annular shaped illuminator, the pupil camera configured to track gross movements of the eye by tracking at least one of an iris or a pupil of the eye; anda hole mirror comprising a central section and a peripheral section surrounding the central section, wherein the central section is substantially transmissive to visible light and aligned to pass the retinal images from the eye to the retinal camera and the peripheral section is substantially reflective to reflect infrared images from the eye to the pupil camera and to reflect the infrared light from the annular shaped illuminator to the eye.

9. The apparatus of claim 2, wherein the camera comprises a retinal camera for capturing retinal images of a retina of the eye.

10. The apparatus of Claim 9, wherein the retinal camera includes an integrated image signal processor that generates gaze tracking data based upon the retinal images, wherein the integrated signal processor is coupled to the controller to output the gaze tracking data to the controller, and wherein monitoring of the gaze direction is executed by the controller based upon the gaze tracking data output from the retinal camera.

11. The apparatus of Claim 1, wherein registering the response of the eye to the first visual stimuli or the second visual stimuli comprises registering user inputs indicating whether the user acknowledges observance of each of the visual stimuli presented.

12. The apparatus of Claim 1, wherein the first portion is disposed in a first quadrant of the display and the second portion is disposed in a second quadrant of the display different than the first quadrant, wherein generating the composite visual193960-P403WOfunction sensitivity map of the eye is based on registered responses of the eye to visual stimuli with fixation targets presented in all quadrants of the display.

13. A method for performing a visual field test on an eye, the method comprising:presenting a first fixation target on a display in a first position offset from a center of the display;presenting first visual stimuli on the display for measuring a visual function sensitivity7of the eye contemporaneously with presenting the first fixation target; registering a response of the eye to the first visual stimuli;presenting a second fixation target on the display in a second position offset from the center of the display, wherein the second position is different than the first position;presenting second visual stimuli on the display for measuring a visual function sensitivity of the eye contemporaneously with presenting the second fixation target;registering a response of the eye to the second visual stimuli; and generating a composite visual function sensitivity map of the eye based on the registered responses of the eye to the first visual stimuli and the second visual stimuli.

14. The method of Claim 13, wherein registering the response of the eye to the first visual stimuli or the second visual stimuli comprises measuring, with a camera positioned to image the eye while the first visual stimuli and the second visual stimuli are presented to the eye, a size of a pupil of the eye in response to the first visual stimuli or the second visual stimuli.

15. The method of Claim 14, further comprising:measuring, with the camera, temporal changes in pupil diameter in response to visual stimuli at a particular position on the display;wherein generating the composite visual function sensitivity map is based on the measured temporal changes in pupil diameter.

16. The method of Claim 14, further comprising:presenting with the display the first visual stimuli or the second visual stimuli at a visual stimulation frequency;203960-P403WOmeasuring, with the camera, pupil diameter in response to the first visual stimuli or the second visual stimuli as function of time;subtracting a pupil diameter baseline from the measured pupil diameter; and identifying a pupil contraction frequency;wherein registering the response of the eye to the first visual stimuli or the second visual stimuli is based on the pupil contraction frequency.

17. The method of Claim 14, further comprising:monitoring a gaze direction of the eye with the camera to identify when the gaze direction has drifted from the fixation target; andmapping a first intended retinal position on a retina, which is associated with a visual stimulus of the first visual stimuli or the second visual stimuli, to an offset retinal position that is actually stimulated by the visual stimulus due to a drifting of the gaze direction, wherein the mapping compensates for the drifting of the gaze direction from the fixation target when the gaze direction is determined to have drifted during presentation of the visual stimulus, wherein the first intended retinal position is stimulated by the visual stimulus on the display when the gaze direction is aligned with the fixation target.

18. The method of Claim 14, further comprising capturing an image of a retina of the eye with the camera.

19. The method of Claim 13, wherein registering the response of the eye to the first visual stimuli or the second visual stimuli comprises registering user inputs indicating whether the user acknowledges observance of each of the visual stimuli presented.

20. The method of Claim 13, wherein the first portion is disposed in a first quadrant of the display and the second portion is disposed in a second quadrant of the display different than the first quadrant, wherein generating the composite visual function sensitivity map of the eye is based on registered responses of the eye to visual stimuli with fixation targets presented in all quadrants of the display.213960-P403WO

Images