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Ocular wavefront aberrations are used to describe retinal image formation in the study and modeling of foveal and peripheral visual functions and visual development. However, classical eye models generate aberration structures that generally do not resemble those of actual eyes, and simplifications such as rotationally symmetric and coaxial surfaces limit the usefulness of many modern eye models. Drawing on wide-field ocular wavefront aberrations measured previously by five laboratories, 28 emmetropic (-0.50 to +0.50 D) and 20 myopic (-1.50 to -4.50 D) individual optical eye models were reverse-engineered by optical design ray-tracing software. This involved an error function that manipulated 27 anatomical parameters, such as curvatures, asphericities, thicknesses, tilts, and translations-constrained within anatomical limits-to drive the output aberrations of each model to agree with the input (measured) aberrations. From those resultant anatomical parameters, three representative eye models were also defined: an ideal emmetropic eye with minimal aberrations (0.00 D), as well as a typical emmetropic eye (-0.02 D) and myopic eye (-2.75 D). The cohorts and individual models are presented and evaluated in terms of output aberrations and established population expectations, such as Seidel aberration theory and ocular chromatic aberrations. Presented applications of the models include the effect of dual focus contact lenses on peripheral optical quality, the comparison of ophthalmic correction modalities, and the projection of object space across the retina during accommodation.
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Emetropía , Miopía , Humanos , Miopía/fisiopatología , Emetropía/fisiología , Refracción Ocular/fisiología , Modelos BiológicosRESUMEN
Motion perception is considered a hyperacuity. The presence of a visual frame of reference to compute relative motion is necessary to achieve this sensitivity [Legge, Gordon E., and F. W. Campbell. "Displacement detection in human vision." Vision Research 21.2 (1981): 205-213.]. However, there is a special condition where humans are unable to accurately detect relative motion: images moving in a direction consistent with retinal slip where the motion is unnaturally amplified can, under some conditions, appear stable [Arathorn, David W., et al. "How the unstable eye sees a stable and moving world." Journal of Vision 13.10.22 (2013)]. In this study, we asked: Is world-fixed retinal image background content necessary for the visual system to compute the direction of eye motion to render in the percept images moving with amplified slip as stable? Or, are non-visual cues sufficient? Subjects adjusted the parameters of a stimulus moving in a random trajectory to match the perceived motion of images moving contingent to the retina. Experiments were done with and without retinal image background content. The perceived motion of stimuli moving with amplified retinal slip was suppressed in the presence of visual content; however, higher magnitudes of motion were perceived under conditions with no visual cues. Our results demonstrate that the presence of retinal image background content is essential for the visual system to compute its direction of motion. The visual content that might be thought to provide a strong frame of reference to detect amplified retinal slips, instead paradoxically drives the misperception of relative motion.
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PURPOSE: To survey the impact of directional reflectivity on structures within optical coherence tomography images in retinal pathology. METHODS: Sets of commercial optical coherence tomography images taken from multiple pupil positions were analyzed. These directional optical coherence tomography sets revealed directionally reflective structures within the retina. After ensuring sufficient image quality, resulting hybrid and composite images were characterized by assessing the Henle fiber layer, outer nuclear layer, ellipsoid zone, and interdigitation zone. Additionally, hybrid images were reviewed for novel directionally reflective pathological features. RESULTS: Cross-sectional directional optical coherence tomography image sets were obtained in 75 eyes of 58 patients having a broad range of retinal pathologies. All cases showed improved visualization of the outer nuclear layer/Henle fiber layer interface, and outer nuclear layer thinning was, therefore, more apparent in several cases. The ellipsoid zone and interdigitation zone also demonstrated attenuation where a geometric impact of underlying pathology affected their orientation. Misdirected photoreceptors were also noted as a consistent direction-dependent change in ellipsoid zone reflectivity between regions of normal and absent ellipsoid zone. CONCLUSION: Directional optical coherence tomography enhances the understanding of retinal anatomy and pathology. This optical contrast yields more accurate identification of retinal structures and possible imaging biomarkers for photoreceptor-related pathology.
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Enfermedades de la Retina , Tomografía de Coherencia Óptica , Humanos , Tomografía de Coherencia Óptica/métodos , Enfermedades de la Retina/diagnóstico , Enfermedades de la Retina/diagnóstico por imagen , Femenino , Masculino , Estudios Transversales , Persona de Mediana Edad , Anciano , Mácula Lútea/diagnóstico por imagen , Mácula Lútea/patología , Adulto , Estudios RetrospectivosRESUMEN
In prior art, advances in adaptive optics scanning laser ophthalmoscope (AOSLO) technology have enabled cones in the human fovea to be resolved in healthy eyes with normal vision and low to moderate refractive errors, providing new insight into human foveal anatomy, visual perception, and retinal degenerative diseases. These high-resolution ophthalmoscopes require careful alignment of each optical subsystem to ensure diffraction-limited imaging performance, which is necessary for resolving the smallest foveal cones. This paper presents a systematic and rigorous methodology for building, aligning, calibrating, and testing an AOSLO designed for imaging the cone mosaic of the central fovea in humans with cellular resolution. This methodology uses a two-stage alignment procedure and thorough system testing to achieve diffraction-limited performance. Results from retinal imaging of healthy human subjects under 30 years of age with refractive errors of less than 3.5 diopters using either 680 nm or 840 nm light show that the system can resolve cones at the very center of the fovea, the region where the cones are smallest and most densely packed.
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Fóvea Central , Oftalmoscopios , Enfermedades de la Retina , Humanos , Calibración , Fóvea Central/diagnóstico por imagen , Rayos Láser , Errores de Refracción , Enfermedades de la Retina/diagnóstico por imagenRESUMEN
The 2-photon effect in vision occurs when two photons of the same wavelength are absorbed by cone photopigment in the retina and create a visual sensation matching the appearance of light close to half their wavelength. This effect is especially salient for infrared light, where humans are mostly insensitive to 1-photon isomerizations and thus any perception is dominated by 2-photon isomerizations. This phenomenon can be made more readily visible using short-pulsed lasers, which increase the likelihood of 2-photon excitation by making photon arrivals at the retina more concentrated in time. Adaptive optics provides another avenue for enhancing the 2-photon effect by focusing light more tightly at the retina, thereby increasing the spatial concentration of incident photons. This article makes three contributions. First, we demonstrate through color-matching experiments that an adaptive optics correction can provide a 25-fold increase in the luminance of the 2-photon effect-a boost equivalent to reducing pulse width by 96%. Second, we provide image-based evidence that the 2-photon effect occurs at the photoreceptor level. Third, we use our results to compute the specifications for a system that could utilize 2-photon vision and adaptive optics to image and stimulate the retina using a single infrared wavelength and reach luminance levels comparable to conventional displays.
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Células Fotorreceptoras Retinianas Conos , Visión Ocular , Humanos , RetinaRESUMEN
Purpose: To measure photoreceptor packing density and S-cone spatial resolution as a function of retinal eccentricity in patients with enhanced S-cone syndrome (ESCS) and to discuss the possible mechanisms supporting their supernormal S-cone acuity. Methods: We used an adaptive optics scanning laser ophthalmoscope (AOSLO) to characterize photoreceptor packing. A custom non-AO display channel was used to measure L/M- and S-cone-mediated visual acuity during AOSLO imaging. Acuity measurements were obtained using a four-alternative, forced-choice, tumbling E paradigm along the temporal meridian between the fovea and 4° eccentricity in five of six patients and in seven control subjects. L/M acuity was tested by presenting long-pass-filtered optotypes on a black background, excluding wavelengths to which S-cones are sensitive. S-cone isolation was achieved using a two-color, blue-on-yellow chromatic adaptation method that was validated on three control subjects. Results: Inter-cone spacing measurements revealed a near-uniform cone density profile (ranging from 0.9-1.5 arcmin spacing) throughout the macula in ESCS. For comparison, normal cone density decreases by a factor of 14 from the fovea to 6°. Cone spacing of ESCS subjects was higher than normal in the fovea and subnormal beyond 2°. Compared to the control subjects (n = 7), S-cone-mediated acuities in patients with ESCS were normal near the fovea and became increasingly supernormal with retinal eccentricity. Beyond 2°, S-cone acuities were superior to L/M-cone-mediated acuity in the ESCS cohort, a reversal of the trend observed in normal retinas. Conclusions: Higher than normal parafoveal cone densities (presumably dominated by S-cones) confer better than normal S-cone-mediated acuity in ESCS subjects.
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Células Fotorreceptoras Retinianas Conos , Degeneración Retiniana , Humanos , Retina , Agudeza Visual , Fóvea Central , OftalmoscopíaRESUMEN
Enhanced S-cone Syndrome (ESCS) is an autosomal recessive inherited retinal disease mostly associated with disease-causing variants in the NR2E3 gene. During retinal development in ESCS, rod photoreceptor precursors are misdirected to form photoreceptors similar to short-wavelength cones, or S-cones. Compared to a normal human retina, patients with ESCS have no rods and significantly increased numbers of S-cones. Night blindness is the main visual symptom, and visual acuity and color vision can be normal at early disease stages. Histology of donor eyes and adaptive optics imaging revealed increased S-cone density outside of the fovea compared to normal. Visual function testing reveals absent rod function and abnormally enhanced sensitivity to short-wavelength light. Unlike most retinal degenerative diseases, ESCS results in a gain in S-cone photoreceptor function. Research involving ESCS could improve understanding of this rare retinal condition and also shed light on the role of NR2E3 expression in photoreceptor survival.
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Receptores Nucleares Huérfanos , Degeneración Retiniana , Humanos , Receptores Nucleares Huérfanos/genética , Receptores Nucleares Huérfanos/metabolismo , Degeneración Retiniana/patología , Retina/patología , Células Fotorreceptoras Retinianas Conos/patologíaRESUMEN
When single cones are stimulated with spots of 543-nm light presented against a white background, subjects report percepts that vary between predominately red, white, and green. However, light of the same spectral composition viewed over a large field under normal viewing conditions looks invariably green and highly saturated. It remains unknown what stimulus parameters are most important for governing the color appearance in the transition between these two extreme cases. The current study varied the size, intensity and retinal motion of stimuli presented in an adaptive optics scanning laser ophthalmoscope. Stimuli were either stabilized on target locations or allowed to drift across the retina with the eye's natural motion. Increasing both stimulus size and intensity led to higher likelihoods that monochromatic spots of light were perceived as green, whereas only higher intensities led to increases in perceived saturation. The data also show an interaction between size and intensity, suggesting that the balance between magnocellular and parvocellular activation may be critical factors for color perception. Surprisingly, under the range of conditions tested, color appearance did not depend on whether stimuli were stabilized. Sequential activation of many cones does not appear to drive hue and saturation perception as effectively as simultaneous activation of many cones.
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Retina , Células Fotorreceptoras Retinianas Conos , Humanos , Retina/fisiología , Células Fotorreceptoras Retinianas Conos/fisiología , Visión Ocular , Percepción de Color/fisiologíaRESUMEN
SIGNIFICANCE: This case report demonstrates the use of novel imaging techniques and functional tests to longitudinally evaluate retinal structure and function after laser retinal injury. The structural and functional prognosis could be predicted with clinical findings, high-resolution retinal imaging, and functional testing. PURPOSE: We present a laser retinal injury case in which an adaptive optics scanning laser ophthalmoscope and adaptive optics-based psychophysics were used to examine and monitor retinal structure and function after accidental exposure to a 1-W infrared laser beam. CASE REPORT: A 23-year-old patient was unwittingly exposed to a 1-W, 852-nm continuous-wave laser at work as they noticed a small central blurry spot in the right eye. An initial eye examination was done 1 day after exposure, and the right eye's acuity was 20/25 -2 . Posterior segment evaluation revealed disrupted outer retina near the right eye's fovea. Adaptive optics imaging 2 weeks after the exposure revealed a 0.50 × 0.75° elliptical area with irregular borders and abnormal cone reflectivity just below the fovea. Starting at 1-month follow-up, structural recovery was observed on optical coherence tomography (OCT). Subsequent adaptive optics imaging showed significant recovery of cone reflectivity. Importantly, adaptive optics microperimetry showed measurable detection thresholds at all affected retinal locations at 6 months. By 10 months, all sites exhibited normal sensitivities. CONCLUSIONS: Retinal structure and function from laser injury can be visualized and measured with OCT, adaptive optics imaging, and psychophysics. An intact Bruch's membrane on OCT and measurable retinal sensitivity by adaptive optics microperimetry may serve as good biomarkers for retinal recovery.
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Lesiones Oculares , Enfermedades de la Retina , Humanos , Adulto Joven , Adulto , Retina/diagnóstico por imagen , Células Fotorreceptoras Retinianas Conos , Tomografía de Coherencia Óptica/métodos , Fóvea Central , Lesiones Oculares/diagnóstico , Lesiones Oculares/etiología , Oftalmoscopía/métodosRESUMEN
This review describes the progress that has been achieved since adaptive optics (AO) was incorporated into the ophthalmoscope a quarter of a century ago, transforming our ability to image the retina at a cellular spatial scale inside the living eye. The review starts with a comprehensive tabulation of AO papers in the field and then describes the technological advances that have occurred, notably through combining AO with other imaging modalities including confocal, fluorescence, phase contrast, and optical coherence tomography. These advances have made possible many scientific discoveries from the first maps of the topography of the trichromatic cone mosaic to exquisitely sensitive measures of optical and structural changes in photoreceptors in response to light. The future evolution of this technology is poised to offer an increasing array of tools to measure and monitor in vivo retinal structure and function with improved resolution and control.
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We describe a system-the Binocular Varichrome and Accommodation Measurement System-that can be used to measure and correct the eye's longitudinal and transverse chromatic aberration (LCA and TCA) and to perform vision tests with custom corrections. We used the system to investigate how LCA and TCA affect visual performance. Specifically, we studied the effects of LCA and TCA on visual acuity, contrast sensitivity, and chromostereopsis. LCA exhibited inter subject variability but followed expected trends compared with previous reports. TCA at the fovea was variable between individuals but with a tendency for the shift at shorter wavelengths to be more temporalward in the visual field in each eye. We found that TCA was generally greater when LCA was corrected. For visual acuity, we found that a measurable benefit was realized only with both LCA and TCA correction unless the TCA was low. For contrast sensitivity, we found that the best sensitivity to a 10-cycle/degree polychromatic grating was attained when LCA and TCA were corrected. Finally, we found that the primary cause of chromostereopsis is the TCA of the eyes.
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Acomodación Ocular , Campos Visuales , Humanos , Agudeza Visual , Fóvea Central , Sensibilidad de ContrasteRESUMEN
PURPOSE: To compare cone structure and function between RPGR- and USH2A-associated retinal degeneration. DESIGN: Retrospective, observational, cross-sectional study. METHODS: This multicenter study included 13 eyes (9 participants) with RPGR-related X-linked retinitis pigmentosa (RPGR), 15 eyes (10 participants) with USH2A-related Usher syndrome type 2 (USH2), 16 eyes (9 participants) with USH2A-related autosomal recessive retinitis pigmentosa (ARRP), and 7 normal eyes (6 participants). Structural measures included cone spacing and density from adaptive optics scanning laser ophthalmoscopy and photoreceptor inner segment (IS), outer segment (OS), and outer nuclear layer (ONL) thickness from optical coherence tomography (OCT) images. OCT angiography images were used to study choriocapillaris flow deficit percent (CCFD). Cone function was assessed by fundus-guided microperimetry. Measures were compared at designated regions using analysis of variance with pairwise comparisons among disease groups, adjusted for disease duration and eccentricity. RESULTS: OCT segmentation revealed shorter OS and IS, with reduced ONL thickness in RPGR compared to normal (OS: P < .001, IS: P = .001, ONL: P = .005), USH2 (OS: P = .01, IS: P = .03, ONL: P = .03), or ARRP (OS: P = .001, ONL: P = .03). Increased cone spacing was observed in both RPGR (P = .03) and USH2 compared with normal (P = .048). The mean CCFD in RPGR was greater than in USH2 (P = .02). Microperimetry demonstrated below-normal regional sensitivity in RPGR (P = .004), USH2 (P = .02), and ARRP (P = .009), without significant intergroup differences. CONCLUSIONS: Outer retinal structure and choriocapillaris perfusion were more abnormal in RPGR- than USH2A-related retinal degenerations, whereas there were no significant differences in below-normal regional sensitivity between each rod-cone degeneration associated with variants in these 2 genes expressed at the photoreceptor-connecting cilium.
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Degeneración Retiniana , Retinitis Pigmentosa , Síndromes de Usher , Humanos , Estudios Transversales , Electrorretinografía , Proteínas de la Matriz Extracelular/genética , Proteínas del Ojo/genética , Células Fotorreceptoras Retinianas Conos/fisiología , Degeneración Retiniana/diagnóstico , Degeneración Retiniana/genética , Retinitis Pigmentosa/diagnóstico , Retinitis Pigmentosa/genética , Estudios Retrospectivos , Tomografía de Coherencia Óptica/métodos , Síndromes de Usher/diagnóstico , Síndromes de Usher/genéticaRESUMEN
Purpose: To present FIAT, a novel optical instrument and analysis package that is designed to elicit and optically record accommodation in human eyes. Methods: FIAT employs a Shack-Hartmann wavefront sensor and a retro-illumination pupil camera that records from a single eye at video rates. It is effective at eliciting accommodation by offering the subject a full-field binocular view of an alternating distant target and a near-eye display. FIAT analysis software computes wave aberrations for each video frame over full- or subpupil sizes and computes accommodative dynamics and accommodative range. Results: The system is validated by showing accurate refraction measurements in model eyes and human eyes with trial lenses. Robust accommodative responses are shown for young eyes, and a lack of accommodative response is shown for a known presbyopes. Accommodative stimulus-response curves from five phakic subjects over a range of ages show expected results. Results from two individuals with monofocal intraocular lenses are shown. Conclusions: FIAT is an effective instrument for making accurate, objective measures of accommodation in phakic and pseudophakic eyes. Translational Relevance: We present a device that can play an important role in the development and testing of accommodating intraocular lenses.
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Lentes Intraoculares , Seudofaquia , Humanos , Acomodación Ocular , Pupila/fisiologíaRESUMEN
In this paper, we present a review of how the various aspects of any study using an eye tracker (such as the instrument, methodology, environment, participant, etc.) affect the quality of the recorded eye-tracking data and the obtained eye-movement and gaze measures. We take this review to represent the empirical foundation for reporting guidelines of any study involving an eye tracker. We compare this empirical foundation to five existing reporting guidelines and to a database of 207 published eye-tracking studies. We find that reporting guidelines vary substantially and do not match with actual reporting practices. We end by deriving a minimal, flexible reporting guideline based on empirical research (Section "An empirically based minimal reporting guideline").
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Movimientos Oculares , Tecnología de Seguimiento Ocular , Humanos , Investigación EmpíricaRESUMEN
Purpose: To provide a tool for calculating radial and tangential retinal magnifications as functions of field angle and retinal shape and to articulate patterns of magnification across the retina for monocular and binocular combinations of prolate-, oblate-, and spherical-shaped retinas. Methods: Formulae were derived to calculate radial and tangential retinal magnifications (mm/deg) from field angle (degrees), retinal asphericity (unitless conic constant), retinal vertex radius of curvature (mm), and nodal point position (mm). Monocular retinal magnifications were determined for eyes with prolate, spherical, and oblate retinas as functions of field angle. Bilateral differences in magnifications were examined for combinations of those eyes. Results: Retinal shape substantially affects magnification profiles even for eyes with the same axial length. Greatest magnification changes across a retina and between eyes, as well as greatest increase in radial-tangential differences (distortion), occur with prolate retinas. Binocular magnification differences were smallest for oblate retinas. Nodal points anterior to the vertex center of curvature and oblate asphericity both cause field-dependent reductions in magnification relative to the fovea (barrel distortion), whereas nodal points posterior to vertex center of curvature and prolate asphericity cause the opposite (pincushion distortion). Retinal magnification differences due to eye shape are much greater than aniseikonia thresholds and chromatic differences in magnification. A spreadsheet tool implements the magnification calculations. Conclusions: Local retinal magnifications as functions of field angle have substantial effects on objective applications (imaging retinal anatomy) and subjective experiences (aniseikonia) and quantify an ocular property that differs across eye shapes and refractive errors. Translational Relevance: Methods are provided to customize the calculation of radial and tangential magnifications across the retina for individual eyes, which will bolster the multifactorial study of the effects of foveal and peripheral optics across eye shapes and refractive errors.
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Aniseiconia , Fosmet , Errores de Refracción , Humanos , Radio (Anatomía) , Retina/diagnóstico por imagen , Campos VisualesRESUMEN
PURPOSE: The purpose of this study was to characterize the benign biological variance of fixational microsaccades in a control population using a tracking scanning laser ophthalmoscope (TSLO), accounting for machine accuracy and precision, to determine ideal testing conditions to detect pathologic change in fixational eye motion (FEM). METHODS: We quantified the accuracy and precision of the TSLO, analyzing measurements made by three operators on a model eye. Repeated, 10-second retinal motion traces were then recorded in 17 controls, 3 times a day (morning, afternoon, and evening), on 3 separate days. Microsaccade metrics (MMs) of frequency, average amplitude, peak velocity, and peak acceleration were extracted. Trace to trace, interday, and intraday variability were calculated across all subjects. RESULTS: Intra-operator and machine variation contributed minimally to total variation, with only 0.007% and 0.14% contribution for frequency and amplitude respectively. Bias was detected, with lower accuracy for higher amplitudes. Participants had an average (SD) microsaccade frequency of 0.84 Hz (0.52 Hz), amplitude of 0.32 degrees (0.11 degrees), peak velocity of 43.68 degrees/s (14.02 degrees/s), and peak acceleration of 13,920.04 degrees/s2 (4,186.84 degrees/s2). The first trace recorded within a session significantly differed from the second two in both microsaccade acceleration and velocity (P < 0.05), and frequency was 0.098 Hz higher in the evenings (P < 0.05). There was no MM difference between days and no evidence of a session-level learning effect (P > 0.05). CONCLUSIONS: The TSLO is both accurate and precise. However, biological inter- and intra-individual variance is present. Trace to trace variability and time of day should be accounted for to optimize detection of pathologic change.
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Fijación Ocular , Oftalmoscopios , Humanos , Rayos Láser , Movimiento (Física) , RetinaRESUMEN
Purpose: To characterize the structure and function of patches of dysflective cones in the foveal region of subjects with normal vision and no known pathology. Dysflective cones are cones that have little or no reflective properties in optical coherence tomography (OCT) or adaptive optics scanning laser ophthalmoscope (AOSLO) images yet exhibit measurable function. Methods: AOSLO images were surveyed for the presence of hyporeflective cone patches, and subjects were brought back for imaging to determine the changes in the hyporeflective region. Adaptive optics microperimetry (AOMP) was used to assess the function of hyporeflective patches in four subjects to determine that they did, in fact, contain dysflective cones. AOMP utilized a stimulus size of less than 1 arcmin to measure thresholds inside and outside the hyporeflective region. Results: Nineteen out of 47 individuals retrospectively reviewed had one or more regions with hyporeflective cone patches in one or both eyes. Ten subjects with hyporeflective cone patches were brought back for imaging. Seven of the 10 had resolved at follow up, and in three subjects new hyporeflective patches appeared in a different location. All AOMP-measured subjects had measurable function in the dysflective cone region. Three out of four subjects showed no difference in light sensitivity in the dysflective region compared to adjacent areas, and one subject showed a 3× reduction in sensitivity in the area. Conclusions: Patches of dysflective cone have been identified in subjects with normal vision and no known pathology, and we have observed instances where dysflective cones in these subjects regain normal reflective properties.
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Fóvea Central/patología , Oftalmoscopía/métodos , Células Fotorreceptoras Retinianas Conos/patología , Tomografía de Coherencia Óptica/métodos , Agudeza Visual , Adulto , Humanos , Masculino , Persona de Mediana Edad , Óptica y Fotónica , Estudios RetrospectivosRESUMEN
One of the main obstacles in high-resolution 3-D retinal imaging is eye motion, which causes blur and distortion artifacts that require extensive post-processing to be corrected. Here, an adaptive optics optical coherence tomography (AOOCT) system with real-time active eye motion correction is presented. Correction of ocular aberrations and of retinal motion is provided by an adaptive optics scanning laser ophthalmoscope (AOSLO) that is optically and electronically combined with the AOOCT system. We describe the system design and quantify its performance. The AOOCT system features an independent focus adjustment that allows focusing on different retinal layers while maintaining the AOSLO focus on the photoreceptor mosaic for high fidelity active motion correction. The use of a high-quality reference frame for eye tracking increases revisitation accuracy between successive imaging sessions, allowing to collect several volumes from the same area. This system enables spatially targeted retinal imaging as well as volume averaging over multiple imaging sessions with minimal correction of motion in post processing.