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Bang SP, Sabesan R, Yoon G. Effects of Neural Adaptation to Habitual Spherical Aberration on Depth of Focus. Res Sq 2024:rs.3.rs-3917931. [PMID: 38410431 PMCID: PMC10896392 DOI: 10.21203/rs.3.rs-3917931/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/28/2024]
Abstract
We investigated how long-term visual experience with habitual spherical aberration (SA) influences subjective depth of focus (DoF). Nine healthy cycloplegic eyes with habitual SAs of different signs and magnitudes were enrolled. An adaptive optics (AO) visual simulator was used to measure through-focus high-contrast visual acuity after correcting all monochromatic aberrations and imposing +0.5 μm and -0.5 μm SAs for a 6-mm pupil. The positive (n=6) and negative (n=3) SA groups ranged from 0.17 to 0.8 μm and from -1.2 to -0.12 μm for a 6-mm pupil, respectively. For the positive habitual SA group, the median DoF with positive AO-induced SA (2.18D) was larger than that with negative AO-induced SA (1.91D); for the negative habitual SA group, a smaller DoF was measured with positive AO-induced SA (1.81D) than that with negative AO-induced SA (2.09D). The difference in the DoF of individual participants between the induced positive and negative SA groups showed a quadratic relationship with the habitual SA. Subjective DoF tended to be larger when the induced SA in terms of the sign and magnitude was closer to the participant's habitual SA, suggesting the importance of considering the habitual SA when applying the extended DoF method using optical or surgical procedures.
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Schleufer S, Pandiyan V, Hazelton B, Coates D, Sabesan R. Poster Session II: Cone spacing and S-cone proportion is sufficient to describe varying S-cone regularity across the human central retina. J Vis 2023; 23:59. [PMID: 38109589 DOI: 10.1167/jov.23.15.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023] Open
Abstract
The topography of S-cones in the human retina is vital to understand short-wavelength sampling of visual space. In humans S-cones have been reported as randomly arranged within 2° eccentricity and semi-regular more peripherally. A model describing how S-cone regularity varies across the retina is yet to be formulated. Here we describe such a model, dependent on 2 parameters - the average distance between neighboring cones and the proportion of S-cones - that is sufficient to explain S-cone regularity across the central retina. Cones were classified using AO-OCT optoretinography in ROIs distributed across the 4 cardinal meridians in 2 subjects (12 ROIs each) between 1.3 - 12.9°eccentricity. The radius of the S-exclusion zone, the area surrounding S-cones where other S-cones are significantly unlikely to appear, was found to be about twice the average distance between neighboring cones in 19/24 mosaics. We found that the measured regularity of S-cone mosaics increases linearly with the increasing proportion of S cones with eccentricity. Using the average distance between neighboring cones and proportion of S-cones per ROI as variables, we created a model to simulate S-cone mosaics that agree well with the observed topography. These results benefit our understanding of the foundational patterns underpinning spectral topography, and the ability to accurately simulate S-cone topography in computational models of early vision.
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Affiliation(s)
- Sierra Schleufer
- University of Washington Department of Ophthalmology and Graduate Program in Neuroscience
| | | | - Bryna Hazelton
- University of Washington eScience Institute and Department of Physics
| | - Daniel Coates
- University of Washington Department of Ophthalmology, University of Houston College of Optometry
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Pandiyan VP, Schleufer S, Bharadwaj P, Sabesan R. Poster Session II: Variation of cone spectral composition in the macula. J Vis 2023; 23:58. [PMID: 38109590 DOI: 10.1167/jov.23.15.58] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023] Open
Abstract
Cone spectral composition is central to the study of color vision and retinal development. There is a lack of information on the spatial distribution of L and M-cones in the macula given that there are no histological methods to separate them. To overcome this gap, cones were spectrally classified using adaptive optics OCT-based optoretinography in human subjects and their variation was described in the macula. To date, we have classified ~130000 total cones in 9 subjects across 79 regions of interest (ROI), with a maximum of 16 retinal eccentricities per subject spread along the 4 cardinal meridians. In 2 two subjects, the variation in cone spectral topography in both eyes was compared. The L: M cone ratio decreased in the foveal slope (0.4°- 1°) but remained relatively uniform in the parafovea from 1.5°- 10° eccentricity. The % S-cones and S-cone density were consistent with prior histology (Curcio et al. 1991). No significant differences were observed in the fellow eyes of the same subject or the distribution of cone types across the 4 cardinal meridians. Decreased L: M cone ratio in the foveal slope suggests earlier differentiation of M-cones than L-cones. The stable L: M cone ratio in the parafovea suggests that the greater fall off in chromatic versus achromatic vision with eccentricity is not explained by cone spectral composition, but is rather attributed to pooling in downstream neurons.
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Bharadwaj P, Slezak E, Pandiyan VP, Coates D, Sabesan R. Contributed Session III: The limits of resolution in the S-cone pathway. J Vis 2023; 23:82. [PMID: 38109566 DOI: 10.1167/jov.23.15.82] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023] Open
Abstract
The resolution of the S-cone pathway is first constrained by the density and arrangement of S-cones in the photoreceptor mosaic. Prior work comparing S-cone isolating visual acuity (sVA) to histological estimates of S-cone density has led to mixed conclusions, likely due to inter-individual differences in the S-cone sub-mosaic. We examined sVA in subjects with spectrally classified cone mosaics to test how the grain of the S-cone sub-mosaic limits resolution. Three observers whose cones were previously classified via adaptive optics (AO)-OCT based optoretinography participated in an sVA task at eccentricities ranging from 1.3° to 12.9° spread along all four cardinal meridians. Observers adapted to yellow light [CIE (0.45, 0.51); 200 cd/m2] for two minutes.Then, acuity was measured using a Tumbling 'E' task that showed blue [CIE (0.16, 0.044); 0.66 cd/m2) letters on the same yellow background, with an S-cone contrast of 0.93 (L/M-cone contrasts <0.01). Simultaneously recorded high-resolution AOSLO videos helped guide stimulus delivery to the spectrally classified retinal area. Measured sVAs were worse than predicted by the calculated S-cone Nyquist limit at all eccentricities, suggesting pooling of information from S-cones. Moreover, this pooling increased with eccentricity. While sVA does not follow the S-cone Nyquist limit, it is in good concordance with the Nyquist limit corresponding to known estimates of the sampling density of small bistratified retinal ganglion cells.
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Affiliation(s)
| | - Emily Slezak
- Department of Ophthalmology, University of Washington
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Liu T, Pandiyan VP, Wendel B, Slezak E, Mustafi D, Chao J, Sabesan R. Contributed Session I: Correlating cone structure and function in retinitis pigmentosa using coarse-scale optoretinography (CoORG). J Vis 2023; 23:69. [PMID: 38109579 DOI: 10.1167/jov.23.15.69] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023] Open
Abstract
Optoretinography (ORG) has the potential to serve as a powerful diagnostic biomarker, owing to its sensitive and objective localization of function and dysfunction. Majority of ORG implementations employ adaptive optics (AO) for imaging activity at a cellular scale. Coarse-scale Optoretinography (CoORG), an ORG paradigm without AO, offers rapid, extended-field recordings and wider applicability in patients with retinal disease, by compromising cellular resolution. This study investigates the feasibility of CoORG in assessing cone dysfunction in patients diagnosed with retinitis pigmentosa (RP). Five RP patients aged 26 - 60 were recruited, alongside age-similar controls. The stimulus for evoking cone activity had a photon density between 15.5x10e6 - 19.7x10e6 photons/μm2, and was centered at 532 ± 5nm. Eight imaging trials per bleach were performed, allowing for 1 min. between successive trials for dark adaptation. The total experimental time for each bleach was 10-20 mins. In RP, cone function, estimated as the change in optical path length in the outer segment in response to a stimulus, was diminished and generally lower than normal controls. This deficit was observed in areas of seemingly normal outer retinal structure. Contrary to normals, no correlation was observed between outer segment length and cone function in RP. This highlights CoORG's potential for early, sensitive detection of retinal dysfunction prior to apparent structural degradation.
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Affiliation(s)
- Teng Liu
- Department of Ophthalmology, University of Washington
| | | | | | - Emily Slezak
- Department of Ophthalmology, University of Washington
| | - Debarshi Mustafi
- Department of Ophthalmology, University of Washington
- Seattle Children's Hospital
| | - Jennifer Chao
- Department of Ophthalmology, University of Washington
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Sabesan R, Grieve K, Hammer DX, Ji N, Marcos S. Introduction to the Feature Issue on Adaptive Optics for Biomedical Applications. Biomed Opt Express 2023; 14:1772-1776. [PMID: 37078031 PMCID: PMC10110319 DOI: 10.1364/boe.488044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Indexed: 05/03/2023]
Abstract
The guest editors introduce a feature issue commemorating the 25th anniversary of adaptive optics in biomedical research.
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Affiliation(s)
- Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Kate Grieve
- Sorbonne Université, INSERM, CNRS, Institut de la Vision, 17 rue Moreau, and CHNO des Quinze-Vingts, INSERM-DGOS CIC 1423, 28 rue de Charenton, F-75012 Paris, France
| | - Daniel X. Hammer
- Center for Devices and Radiological Health (CDRH), U. S. Food and Drug Administration (FDA), Silver Spring, MD 20993, USA
| | - Na Ji
- Department of Physics, Department of Molecular & Cellular Biology, University of California, Berkeley, CA 94720, USA
| | - Susana Marcos
- Visual Optics and Biophotonics Laboratory, Instituto de Óptica, Consejo Superior de Investigaciones Científicas, Calle Serrano 121, Madrid, 28006, Spain
- Center for Visual Sciences; The Institute of Optics and Flaum Eye Institute, University of Rochester, Rochester, NY 14642, USA
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Pandiyan VP, Schleufer S, Slezak E, Fong J, Upadhyay R, Roorda A, Ng R, Sabesan R. Characterizing cone spectral classification by optoretinography. Biomed Opt Express 2022; 13:6574-6594. [PMID: 36589563 PMCID: PMC9774847 DOI: 10.1364/boe.473608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Revised: 10/26/2022] [Accepted: 10/27/2022] [Indexed: 05/02/2023]
Abstract
Light propagation in photoreceptor outer segments is affected by photopigment absorption and the phototransduction amplification cascade. Photopigment absorption has been studied using retinal densitometry, while recently, optoretinography (ORG) has provided an avenue to probe changes in outer segment optical path length due to phototransduction. With adaptive optics (AO), both densitometry and ORG have been used for cone spectral classification based on the differential bleaching signatures of the three cone types. Here, we characterize cone classification by ORG, implemented in an AO line-scan optical coherence tomography (OCT), and compare it against densitometry. The cone mosaics of five color normal subjects were classified using ORG showing high probability (∼0.99), low error (<0.22%), high test-retest reliability (∼97%), and short imaging durations (< 1 hour). Of these, the cone spectral assignments in two subjects were compared against AO-scanning laser opthalmoscope densitometry. High agreement (mean: 91%) was observed between the two modalities in these two subjects, with measurements conducted 6-7 years apart. Overall, ORG benefits from higher sensitivity and dynamic range to probe cone photopigments compared to densitometry, and thus provides greater fidelity for cone spectral classification.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Sierra Schleufer
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
| | - Emily Slezak
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - James Fong
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Rishi Upadhyay
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, Berkeley, CA, USA
| | - Ren Ng
- Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, CA, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, USA
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Jiang X, Liu T, Pandiyan VP, Slezak E, Sabesan R. Coarse-scale optoretinography (CoORG) with extended field-of-view for normative characterization. Biomed Opt Express 2022; 13:5989-6002. [PMID: 36733759 PMCID: PMC9872880 DOI: 10.1364/boe.473475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/04/2022] [Accepted: 10/11/2022] [Indexed: 05/02/2023]
Abstract
Optoretinography (ORG) has the potential to be an effective biomarker for light-evoked retinal activity owing to its sensitive, objective, and precise localization of retinal function and dysfunction. Many ORG implementations have used adaptive optics (AO) to localize activity on a cellular scale. However, the use of AO restricts field-of-view (FOV) to the isoplanatic angle, necessitating the montaging of multiple regions-of-interest to cover an extended field. In addition, subjects with lens opacities, increased eye movements and decreased mobility pose challenges for effective AO operation. Here, we developed a coarse-scale ORG (CoORG) system without AO, which accommodates FOVs up to 5.5 deg. in a single acquisition. The system is based on a line-scan spectral domain OCT with volume rates of up to 32 Hz (16,000 B-frames per second). For acquiring ORGs, 5.5 deg. wide OCT volumes were recorded after dark adaptation and two different stimulus bleaches. The stimulus-evoked optical phase change was calculated from the reflections encasing the cone outer segments and its variation was assessed vs. eccentricity in 12 healthy subjects. The general behavior of ΔOPL vs. time mimicked published reports. High trial-to-trial repeatability was observed across subjects and with eccentricity. Comparison of ORG between CoORG and AO-OCT based ORG at 1.5°, 2.5°, and 3.5° eccentricity showed an excellent agreement in the same 2 subjects. The amplitude of the ORG response decreased with increasing eccentricity. The variation of ORG characteristics between subjects and versus eccentricity was well explained by the photon density of the stimulus on the retina and the outer segment length. Overall, the high repeatability and rapid acquisition over an extended field enabled the normative characterization of the cone ORG response in healthy eyes, and provides a promising avenue for translating ORG for widespread clinical application.
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Affiliation(s)
- Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Teng Liu
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
| | - Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Emily Slezak
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
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Ng CJ, Sabesan R, Barbot A, Banks MS, Yoon G. Suprathreshold Contrast Perception Is Altered by Long-term Adaptation to Habitual Optical Blur. Invest Ophthalmol Vis Sci 2022; 63:6. [PMID: 36223102 PMCID: PMC9583751 DOI: 10.1167/iovs.63.11.6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Purpose To investigate whether visual experience with habitual blur alters the neural processing of suprathreshold contrast in emmetropic and highly aberrated eyes. Methods A large stroke adaptive optics system was used to correct ocular aberrations. Contrast constancy was assessed psychophysically in emmetropic and keratoconic eyes using a contrast matching paradigm. Participants adjusted the contrasts of gratings at various spatial frequencies to match the contrast perception of a reference grating at 4 c/deg. Matching was done both with fully corrected and uncorrected ocular aberrations. Optical correction allowed keratoconus patients to perceive high spatial frequencies that they have not experienced for some time. Results Emmetropic observers exhibited contrast constancy both with their native aberrations and when their aberrations were corrected. Keratoconus patients exhibited contrast constancy with their uncorrected, native optics but they did not exhibit constancy during adaptive optics correction. Instead. they exhibited striking underconstancy: they required more contrast at high spatial frequencies than the contrast of the 4-c/deg stimulus to make them seem to have the same contrast. Conclusions The presence of contrast constancy in emmetropes and keratoconus patients viewing with their native optics suggests that they have learned to amplify neural signals to offset the effects of habitual optical aberrations. The fact that underconstancy was observed in keratoconus patients when their optics were corrected suggests that they were unable to learn the appropriate neural amplification because they did not have experience with fine spatial detail. These results show that even adults can learn neural amplification to counteract the effects of their own optical aberrations.
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Affiliation(s)
- Cherlyn J. Ng
- College of Optometry, University of Houston, Houston, TX, United States
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
| | - Antoine Barbot
- Department of Ophthalmology, University of Rochester, Rochester, NY, United States
| | - Martin S. Banks
- School of Optometry, University of California, Berkeley, CA, United States
| | - Geunyoung Yoon
- College of Optometry, University of Houston, Houston, TX, United States
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Bang SP, Aaker JD, Sabesan R, Yoon G. Improvement of neural contrast sensitivity after long-term adaptation in pseudophakic eyes. Biomed Opt Express 2022; 13:4528-4538. [PMID: 36187236 PMCID: PMC9484441 DOI: 10.1364/boe.465117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/16/2022] [Accepted: 07/19/2022] [Indexed: 05/02/2023]
Abstract
An adaptive optics (AO) system was used to investigate the effect of long-term neural adaptation to the habitual optical profile on neural contrast sensitivity in pseudophakic eyes after the correction of all aberrations, defocus, and astigmatism. Pseudophakic eyes were assessed at 4 and 8 months postoperatively for changes in visual performance. Visual benefit was observed in all eyes at all spatial frequencies after AO correction. The average visual benefit across spatial frequencies was higher in the pseudophakic group (3.31) at 4 months postoperatively compared to the normal group (2.41). The average contrast sensitivity after AO correction in the pseudophakic group improved by a factor of 1.73 between 4 and 8 months postoperatively. Contrast sensitivity in pseudophakic eyes was poorer, which could be attributed to long-term adaptation to the habitual optical profiles before the cataract surgery, in conjunction with age-related vision loss. Improved visual performance in pseudophakic eyes suggests that the aged neural system can be re-adapted for altered ocular optics.
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Affiliation(s)
- Seung Pil Bang
- Biomedical Engineering, Flaum Eye Institute, Center for Visual Sciences, University of Rochester, Rochester, NY, USA
| | | | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Geunyoung Yoon
- College of Optometry, University of Houston, Houston, TX, USA
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Schleufer S, Pandiyan V, Bharadwaj P, Sabesan R. In-vivo classification of human cone photoreceptors reveals crystalline S-cone sub-mosaics in the central retina. J Vis 2022. [PMID: 35120246 DOI: 10.1167/jov.22.3.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The topography of S-cones in the macula sets the neural constraints for coding the short-wavelength spectrum of color vision. We find that S-cones tile the central human retina with a non-random crystalline arrangement. This finding departs from previous studies, likely due to limited sampling. In 2 subjects we classified cones using Adaptive Optics Line-scan OCT and a bleaching stimulus of 660±10 nm. 8 ROIs per subject were classified at 1.5° and ~4° eccentricity across the 4 meridians. Numbers of total and S- cones per ROI spanned 541-3545 (mean: 1823) and 38-171 (mean: 99), respectively. We measured S-cone spacing in each ROI using the established method of Density Recovery Profile (DRP). To compare with random arrangement, we generated 1000 Monte Carlo (MC) simulations of each ROI such that its cone locations were maintained but locations of S-cones within it were randomized. We then measured the radius in units of inter-cone distance for which S-cone density was significantly lower than MC distributions, finding low density in a 1-cone radius in 13/16 ROIs (8/8 at 1.5°, p ≤ .037. 5/8 at 3.5°-4.5°, p ≤ .002), and up to a 2-cone radius in 12/16 ROIs (7/8 at 1.5°, p ≤ .002. 5/8 at 3.5°-4.5° p ≤ .003). Further experiments will include additional human subjects, ROIs at higher eccentricities, and classification using a short-wavelength bleach. Together, these findings have important implications for retinal development and color coding retinal circuits.
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Affiliation(s)
- Sierra Schleufer
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
| | - Vimal Pandiyan
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
| | - Palash Bharadwaj
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA, United States
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12
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Veysset D, Ling T, Zhuo Y, Pandiyan VP, Sabesan R, Palanker D. Interferometric imaging of thermal expansion for temperature control in retinal laser therapy. Biomed Opt Express 2022; 13:728-743. [PMID: 35284191 PMCID: PMC8884207 DOI: 10.1364/boe.448803] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Revised: 12/27/2021] [Accepted: 12/28/2021] [Indexed: 06/14/2023]
Abstract
Precise control of the temperature rise is a prerequisite for proper photothermal therapy. In retinal laser therapy, the heat deposition is primarily governed by the melanin concentration, which can significantly vary across the retina and from patient to patient. In this work, we present a method for determining the optical and thermal properties of layered materials, directly applicable to the retina, using low-energy laser heating and phase-resolved optical coherence tomography (pOCT). The method is demonstrated on a polymer-based tissue phantom heated with a laser pulse focused onto an absorbing layer buried below the phantom's surface. Using a line-scan spectral-domain pOCT, optical path length changes induced by the thermal expansion were extracted from sequential B-scans. The material properties were then determined by matching the optical path length changes to a thermo-mechanical model developed for fast computation. This method determined the absorption coefficient with a precision of 2.5% and the temperature rise with a precision of about 0.2°C from a single laser exposure, while the peak did not exceed 8°C during 1 ms pulse, which is well within the tissue safety range and significantly more precise than other methods.
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Affiliation(s)
- David Veysset
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Tong Ling
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
- Present address: School of Chemical and Biomedical Engineering, Nanyang Technological University, Singapore 637457, Singapore
| | - Yueming Zhuo
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | | | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
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Abstract
It is well known that crowding, the disruptive influence of flanking items on identification of targets, is the primary limiting factor to object identification in the periphery, while limits in the fovea are more determined by the ability to resolve individual items. Whether this is a dichotomous or merely a quantitative difference, and the transition between these two regimes, has remained unexplained. Here, using an adaptive optics system for optimal control of optical and stimulus factors, we measured threshold acuity for identification of Tumbling Es flanked by bars at a variety of flanker spacings and eight eccentricities in the parafovea. Thresholds at each eccentricity were influenced by resolution, contour interaction, and a saturating pedestal effect. When target-flanker spacing was plotted in terms of cortical distance, a single canonical clipped-line fit unified the resultant curves. The critical spacing for letters flanked by bars was found to be 1.3 to 1.5 cortical millimeters, corresponding to approximately 0.1*E outside the fovea.
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Affiliation(s)
- Daniel R Coates
- College of Optometry, University of Houston, Houston, TX, USA
| | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Dennis M Levi
- Herbert Wertheim School of Optometry & Vision Science, Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
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Pandiyan VP, Jiang X, Kuchenbecker JA, Sabesan R. Reflective mirror-based line-scan adaptive optics OCT for imaging retinal structure and function. Biomed Opt Express 2021; 12:5865-5880. [PMID: 34692221 PMCID: PMC8515964 DOI: 10.1364/boe.436337] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 08/16/2021] [Accepted: 08/20/2021] [Indexed: 05/06/2023]
Abstract
Line-scan OCT incorporated with adaptive optics (AO) offers high resolution, speed, and sensitivity for imaging retinal structure and function in vivo. Here, we introduce its implementation with reflective mirror-based afocal telescopes, optimized for imaging light-induced retinal activity (optoretinography) and weak retinal reflections at the cellular scale. A non-planar optical design was followed based on previous recommendations with key differences specific to a line-scan geometry. The three beam paths fundamental to an OCT system -illumination/sample, detection, and reference- were modeled in Zemax optical design software to yield theoretically diffraction-limited performance over a 2.2 deg. field-of-view and 1.5 D vergence range at the eye's pupil. The performance for imaging retinal structure was exemplified by cellular-scale visualization of retinal ganglion cells, macrophages, foveal cones, and rods in human observers. The performance for functional imaging was exemplified by resolving the light-evoked optical changes in foveal cone photoreceptors where the spatial resolution was sufficient for cone spectral classification at an eccentricity 0.3 deg. from the foveal center. This enabled the first in vivo demonstration of reduced S-cone (short-wavelength cone) density in the human foveola, thus far observed only in ex vivo histological preparations. Together, the feasibility for high resolution imaging of retinal structure and function demonstrated here holds significant potential for basic science and translational applications.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Co-first authors with equal contribution
| | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
- Co-first authors with equal contribution
| | - James A Kuchenbecker
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
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15
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Li Z, Pandiyan VP, Maloney-Bertelli A, Jiang X, Li X, Sabesan R. Correcting intra-volume distortion for AO-OCT using 3D correlation based registration. Opt Express 2020; 28:38390-38409. [PMID: 33379652 PMCID: PMC7771894 DOI: 10.1364/oe.410374] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 11/15/2020] [Accepted: 11/19/2020] [Indexed: 05/18/2023]
Abstract
Adaptive optics (AO) based ophthalmic imagers, such as scanning laser ophthalmoscopes (SLO) and optical coherence tomography (OCT), are used to evaluate the structure and function of the retina with high contrast and resolution. Fixational eye movements during a raster-scanned image acquisition lead to intra-frame and intra-volume distortion, resulting in an inaccurate reproduction of the underlying retinal structure. For three-dimensional (3D) AO-OCT, segmentation-based and 3D correlation based registration methods have been applied to correct eye motion and achieve a high signal-to-noise ratio registered volume. This involves first selecting a reference volume, either manually or automatically, and registering the image/volume stream against the reference using correlation methods. However, even within the chosen reference volume, involuntary eye motion persists and affects the accuracy with which the 3D retinal structure is finally rendered. In this article, we introduced reference volume distortion correction for AO-OCT using 3D correlation based registration and demonstrate a significant improvement in registration performance via a few metrics. Conceptually, the general paradigm follows that developed previously for intra-frame distortion correction for 2D raster-scanned images, as in an AOSLO, but extended here across all three spatial dimensions via 3D correlation analyses. We performed a frequency analysis of eye motion traces before and after intra-volume correction and revealed how periodic artifacts in eye motion estimates are effectively reduced upon correction. Further, we quantified how the intra-volume distortions and periodic artifacts in the eye motion traces, in general, decrease with increasing AO-OCT acquisition speed. Overall, 3D correlation based registration with intra-volume correction significantly improved the visualization of retinal structure and estimation of fixational eye movements.
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Affiliation(s)
- Zhenghan Li
- Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu, Sichuan 610209, China
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, Sichuan 610209, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, USA
- These authors contributed equally to this work
| | - Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, USA
- These authors contributed equally to this work
| | | | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, USA
| | - Xinyang Li
- Key Laboratory on Adaptive Optics, Chinese Academy of Sciences, Chengdu, Sichuan 610209, China
- Institute of Optics and Electronics, Chinese Academy of Sciences, Chengdu, Sichuan 610209, China
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, Washington 98109, USA
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16
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Boyle KC, Chen ZC, Ling T, Pandiyan VP, Kuchenbecker J, Sabesan R, Palanker D. Mechanisms of Light-Induced Deformations in Photoreceptors. Biophys J 2020; 119:1481-1488. [PMID: 33031739 PMCID: PMC7642315 DOI: 10.1016/j.bpj.2020.09.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 09/02/2020] [Accepted: 09/08/2020] [Indexed: 01/11/2023] Open
Abstract
Biological cells deform on a nanometer scale when their transmembrane voltage changes, an effect that has been visualized during the action potential using quantitative phase imaging. Similar changes in the optical path length have been observed in photoreceptor outer segments after a flash stimulus via phase-resolved optical coherence tomography. These optoretinograms reveal a fast, millisecond-scale contraction of the outer segments by tens of nanometers, followed by a slow (hundreds of milliseconds) elongation reaching hundreds of nanometers. Ultrafast measurements of the contractile response using line-field phase-resolved optical coherence tomography show a logarithmic increase in amplitude and a decreasing time to peak with increasing stimulus intensity. We present a model that relates the early receptor potential to these deformations based on the voltage-dependent membrane tension-the mechanism observed earlier in neurons and other electrogenic cells. The early receptor potential is caused by conformational changes in opsins after photoisomerization, resulting in the fractional shift of the charge across the disk membrane. Lateral repulsion of the ions on both sides of the membrane affects its surface tension and leads to its lateral expansion. Because the volume of the disks does not change on a millisecond timescale, their lateral expansion leads to an axial contraction of the outer segment. With increasing stimulus intensity and the resulting tension, the area expansion coefficient of the disk membrane also increases as thermally induced fluctuations are pulled flat, resisting further expansion. This leads to the logarithmic saturation observed in measurements as well as the peak shift in time. This imaging technique therefore relates the structural changes in the photoreceptor to the underlying neurological function of transducing light into electrical signals. Such label-free optical monitoring of neural activity using fast interferometry may be applicable not only to optoretinography but also to neuroscience in general.
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Affiliation(s)
- K C Boyle
- Department of Electrical Engineering, Stanford University, Stanford, California; Hansen Experimental Physics Laboratory, Stanford University, Stanford, California.
| | - Z C Chen
- Department of Electrical Engineering, Stanford University, Stanford, California; Hansen Experimental Physics Laboratory, Stanford University, Stanford, California
| | - T Ling
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California; Department of Ophthalmology, Stanford University, Stanford, California
| | - V P Pandiyan
- Department of Ophthalmology, University of Washington, Seattle, Washington
| | - J Kuchenbecker
- Department of Ophthalmology, University of Washington, Seattle, Washington
| | - R Sabesan
- Department of Ophthalmology, University of Washington, Seattle, Washington.
| | - D Palanker
- Hansen Experimental Physics Laboratory, Stanford University, Stanford, California; Department of Ophthalmology, Stanford University, Stanford, California.
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Pandiyan VP, Maloney-Bertelli A, Kuchenbecker JA, Boyle KC, Ling T, Chen ZC, Park BH, Roorda A, Palanker D, Sabesan R. The optoretinogram reveals the primary steps of phototransduction in the living human eye. Sci Adv 2020; 6:6/37/eabc1124. [PMID: 32917686 PMCID: PMC9222118 DOI: 10.1126/sciadv.abc1124] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Accepted: 07/24/2020] [Indexed: 05/05/2023]
Abstract
Photoreceptors initiate vision by converting photons to electrical activity. The onset of the phototransduction cascade is marked by the isomerization of photopigments upon light capture. We revealed that the onset of phototransduction is accompanied by a rapid (<5 ms), nanometer-scale electromechanical deformation in individual human cone photoreceptors. Characterizing this biophysical phenomenon associated with phototransduction in vivo was enabled by high-speed phase-resolved optical coherence tomography in a line-field configuration that allowed sufficient spatiotemporal resolution to visualize the nanometer/millisecond-scale light-induced shape change in photoreceptors. The deformation was explained as the optical manifestation of electrical activity, caused due to rapid charge displacement following isomerization, resulting in changes of electrical potential and surface tension within the photoreceptor disc membranes. These all-optical recordings of light-induced activity in the human retina constitute an optoretinogram and hold remarkable potential to reveal the biophysical correlates of neural activity in health and disease.
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Affiliation(s)
| | | | | | - Kevin C Boyle
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Tong Ling
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Zhijie Charles Chen
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Electrical Engineering, Stanford University, Stanford, CA 94305, USA
| | - B Hyle Park
- Department of Bioengineering, University of California, Riverside, CA 92521, USA
| | - Austin Roorda
- School of Optometry, University of California, Berkeley, CA 94720, USA
| | - Daniel Palanker
- Hansen Experimental Physics Laboratory, Stanford, CA 94305, USA
- Department of Ophthalmology, Stanford University, Stanford, CA 94305, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA 98109, USA.
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18
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Pandiyan VP, Jiang X, Maloney-Bertelli A, Kuchenbecker JA, Sharma U, Sabesan R. High-speed adaptive optics line-scan OCT for cellular-resolution optoretinography. Biomed Opt Express 2020; 11:5274-5296. [PMID: 33014614 PMCID: PMC7510866 DOI: 10.1364/boe.399034] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 08/05/2020] [Accepted: 08/19/2020] [Indexed: 05/15/2023]
Abstract
Optoretinography-the non-invasive, optical imaging of light-induced functional activity in the retina-stands to provide a critical biomarker for testing the safety and efficacy of new therapies as well as their rapid translation to the clinic. Optical phase change in response to light, as readily accessible in phase-resolved OCT, offers a path towards all-optical imaging of retinal function. However, typical human eye motion adversely affects phase stability. In addition, recording fast light-induced retinal events necessitates high-speed acquisition. Here, we introduce a high-speed line-scan spectral domain OCT with adaptive optics (AO), aimed at volumetric imaging and phase-resolved acquisition of retinal responses to light. By virtue of parallel acquisition of an entire retinal cross-section (B-scan) in a single high-speed camera frame, depth-resolved tomograms at speeds up to 16 kHz were achieved with high sensitivity and phase stability. To optimize spectral and spatial resolution, an anamorphic detection paradigm was introduced, enabling improved light collection efficiency and signal roll-off compared to traditional methods. The benefits in speed, resolution and sensitivity were exemplified in imaging nanometer-millisecond scale light-induced optical path length changes in cone photoreceptor outer segments. With 660 nm stimuli, individual cone responses readily segregated into three clusters, corresponding to long, middle, and short-wavelength cones. Recording such optoretinograms on spatial scales ranging from individual cones, to 100 µm-wide retinal patches offers a robust and sensitive biomarker for cone function in health and disease.
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Affiliation(s)
- Vimal Prabhu Pandiyan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Aiden Maloney-Bertelli
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - James A Kuchenbecker
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Utkarsh Sharma
- Catapult Sky LLC, 34116 Blue Heron Dr, Solon, OH 44139, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA 98109, USA
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19
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Neitz A, Jiang X, Kuchenbecker JA, Domdei N, Harmening W, Yan H, Yeonan-Kim J, Patterson SS, Neitz M, Neitz J, Coates DR, Sabesan R. Effect of cone spectral topography on chromatic detection sensitivity. J Opt Soc Am A Opt Image Sci Vis 2020; 37:A244-A254. [PMID: 32400553 PMCID: PMC7231539 DOI: 10.1364/josaa.382384] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 03/06/2020] [Indexed: 05/06/2023]
Abstract
The spatial and spectral topography of the cone mosaic set the limits for detection and discrimination of chromatic sinewave gratings. Here, we sought to compare the spatial characteristics of mechanisms mediating hue perception against those mediating chromatic detection in individuals with known spectral topography and with optical aberrations removed with adaptive optics. Chromatic detection sensitivity in general exceeded previous measurements and decreased monotonically for increasingly skewed cone spectral compositions. The spatial grain of hue perception was significantly coarser than chromatic detection, consistent with separate neural mechanisms for color vision operating at different spatial scales.
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Affiliation(s)
- Alexandra Neitz
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - Xiaoyun Jiang
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - James A. Kuchenbecker
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - Niklas Domdei
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Wolf Harmening
- Department of Ophthalmology, University of Bonn, Bonn, Germany
| | - Hongyi Yan
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - Jihyun Yeonan-Kim
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - Sara S. Patterson
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - Maureen Neitz
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - Jay Neitz
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
| | - Daniel R. Coates
- College of Optometry, University of Houston, Houston, Texas 77004, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, Washington 98195, USA
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20
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Reiniger JL, Lobecke AC, Sabesan R, Bach M, Verbakel F, de Brabander J, Holz FG, Berendschot TTJM, Harmening WM. Habitual higher order aberrations affect Landolt but not Vernier acuity. J Vis 2020; 19:11. [PMID: 31100127 PMCID: PMC6526962 DOI: 10.1167/19.5.11] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
To assess whether the eye's optical imperfections are relevant for hyperacute vision, we measured ocular wave aberrations, visual hyperacuity, and acuity thresholds in 31 eyes of young adults. Although there was a significant positive correlation between the subjects' performance in Vernier- and Landolt-optotype acuity tasks, we found clear differences in how far both acuity measures correlate with the eyes' optics. Landolt acuity thresholds were significantly better in eyes with low higher order aberrations and high visual Strehl ratios (r2 = 0.22, p = 0.009), and significantly positively correlated with axial length (r2 = 0.15, p = 0.03). A retinal image quality metric, calculated as two-dimensional correlation between perfect and actual retinal image, was also correlated with Landolt acuity thresholds (r2 = 0.27, p = 0.003). No such correlations were found with Vernier acuity performance (r2 < 0.03, p > 0.3). Based on these results, hyperacuity thresholds are, contrary to resolution acuity, not affected by higher order aberrations of the eye.
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Affiliation(s)
| | - Anne C Lobecke
- Department of Neurobiology, University of Bielefeld, Germany
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | - Michael Bach
- Eye Center, Medical Center-University of Freiburg, Faculty of Medicine, University of Freiburg, Germany
| | | | | | - Frank G Holz
- Department of Ophthalmology, University of Bonn, Germany
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21
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Coates DR, Levi DM, Sabesan R. The gradient of parafoveal crowding. J Vis 2019. [DOI: 10.1167/19.10.13b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
| | - Dennis M Levi
- School of Optometry, University of California, Berkeley
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22
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Jiang X, Kuchenbecker JA, Touch P, Sabesan R. Measuring and compensating for ocular longitudinal chromatic aberration. Optica 2019; 6:981-990. [PMID: 33614858 PMCID: PMC7894623 DOI: 10.1364/optica.6.000981] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 06/15/2019] [Indexed: 05/18/2023]
Abstract
It is well known that the eye's optics and media introduce monochromatic and chromatic aberration unique to each individual. Once monochromatic aberrations are removed with adaptive optics (AO), longitudinal chromatic aberrations (LCA) define the fidelity for multi-wavelength, high-resolution vision testing and retinal imaging. AO vision simulation systems and AO scanning laser ophthalmoscopes (AOSLOs) typically use the average population LCA to compensate for focus offsets between different wavelengths precluding fine, individualized control. The eye's LCA has been characterized extensively using either subjective (visual perception) or objective (imaging) methods. Classically, these have faced inconsistencies due to extraneous factors related to depth of focus, monochromatic aberration, and wavelength-dependent light interactions with retinal tissue. Here, we introduce a filter-based Badal LCA compensator that offers the flexibility to tune LCA for each individual eye and demonstrate its feasibility for vision testing and imaging using multiple wavelengths simultaneously. Incorporating the LCA compensator in an AOSLO allowed the first objective measurements of LCA based on confocal, multi-wavelength foveal cone images and its comparison to measures obtained subjectively. The objective LCA thus obtained was consistent with subjective estimates in the same individuals and hence resolves the prior discrepancies between them. Overall, the described approach will benefit applications in retinal imaging and vision testing where the focus of multiple wavelengths needs to be controlled independently and simultaneously.
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23
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Neitz A, Jiang X, Kuchenbecker JA, Patterson SS, Doebley AL, Neitz M, Neitz J, Sabesan R. High acuity vision corrected for chromatic and monochromatic aberrations is associated with color discrimination without red-green or blue-yellow sensations. J Vis 2019. [DOI: 10.1167/19.8.12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
| | | | | | | | | | | | - Jay Neitz
- Ophthalmology University of Washington
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24
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Abstract
Crowding is the substantial interference of neighboring items on target identification. Crowding with letter stimuli has been studied primarily in the visual periphery, with conflicting results for foveal stimuli. While a cortical locus for peripheral crowding is well established (with a large spatial extent up to half of the target eccentricity), disentangling the contributing factors in the fovea is more challenging due to optical limitations. Here, we used adaptive optics (AO) to overcome ocular aberrations and employed high-resolution stimuli to precisely characterize foveal lateral interactions with high-contrast letters flanked by letters. Crowding was present, with a maximal edge-to-edge interference zone of 0.75-1.3 minutes at typical unflanked performance levels. In agreement with earlier foveal contour interaction studies, performance was non-monotonic, revealing a recovery effect with proximal flankers. Modeling revealed that the deleterious effects of flankers can be described by a single function across stimulus sizes when the degradation is expressed as a reduction in sensitivity (expressed in Z-score units). The recovery, however, did not follow this pattern, likely reflecting a separate mechanism. Additional analysis reconciles multiple results from the literature, including the observed scale invariance of center-to-center spacing, as well as the size independence of edge-to-edge spacing.
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Affiliation(s)
- Daniel R Coates
- College of Optometry, University of Houston, Houston, TX, USA.
| | - Dennis M Levi
- School of Optometry, Vision Science Graduate Group, Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA, USA
| | - Phanith Touch
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington School of Medicine, Seattle, WA, USA
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Schmidt BP, Sabesan R, Tuten WS, Neitz J, Roorda A. Sensations from a single M-cone depend on the activity of surrounding S-cones. Sci Rep 2018; 8:8561. [PMID: 29867090 PMCID: PMC5986870 DOI: 10.1038/s41598-018-26754-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 05/18/2018] [Indexed: 11/15/2022] Open
Abstract
Color vision requires the activity of cone photoreceptors to be compared in post-receptoral circuitry. Decades of psychophysical measurements have quantified the nature of these comparative interactions on a coarse scale. How such findings generalize to a cellular scale remains unclear. To answer that question, we quantified the influence of surrounding light on the appearance of spots targeted to individual cones. The eye's aberrations were corrected with adaptive optics and retinal position was precisely tracked in real-time to compensate for natural movement. Subjects reported the color appearance of each spot. A majority of L-and M-cones consistently gave rise to the sensation of white, while a smaller group repeatedly elicited hue sensations. When blue sensations were reported they were more likely mediated by M- than L-cones. Blue sensations were elicited from M-cones against a short-wavelength light that preferentially elevated the quantal catch in surrounding S-cones, while stimulation of the same cones against a white background elicited green sensations. In one of two subjects, proximity to S-cones increased the probability of blue reports when M-cones were probed. We propose that M-cone increments excited both green and blue opponent pathways, but the relative activity of neighboring cones favored one pathway over the other.
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Affiliation(s)
- Brian P Schmidt
- Graduate Program in Neuroscience, University of Washington, Seattle, WA, 98109, USA.
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, CA, 94720, USA.
| | - Ramkumar Sabesan
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, CA, 94720, USA
- Department of Ophthalmology, University of Washington, Seattle, WA, 98109, USA
| | - William S Tuten
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, CA, 94720, USA
| | - Jay Neitz
- Department of Ophthalmology, University of Washington, Seattle, WA, 98109, USA
| | - Austin Roorda
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, CA, 94720, USA
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26
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Winter S, Sabesan R, Tiruveedhula P, Privitera C, Unsbo P, Lundström L, Roorda A. Transverse chromatic aberration across the visual field of the human eye. J Vis 2017; 16:9. [PMID: 27832270 PMCID: PMC5109981 DOI: 10.1167/16.14.9] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The purpose of this study was to measure the transverse chromatic aberration (TCA) across the visual field of the human eye objectively. TCA was measured at horizontal and vertical field angles out to ±15° from foveal fixation in the right eye of four subjects. Interleaved retinal images were taken at wavelengths 543 nm and 842 nm in an adaptive optics scanning laser ophthalmoscope (AOSLO). To obtain true measures of the human eye's TCA, the contributions of the AOSLO system's TCA were measured using an on-axis aligned model eye and subtracted from the ocular data. The increase in TCA was found to be linear with eccentricity, with an average slope of 0.21 arcmin/degree of visual field angle (corresponding to 0.41 arcmin/degree for 430 nm to 770 nm). The absolute magnitude of ocular TCA varied between subjects, but was similar to the resolution acuity at 10° in the nasal visual field, encompassing three to four cones. Therefore, TCA can be visually significant. Furthermore, for high-resolution imaging applications, whether visualizing or stimulating cellular features in the retina, it is important to consider the lateral displacements between wavelengths and the variation in blur over the visual field.
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Affiliation(s)
- Simon Winter
- Department of Applied Physics, Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Stockholm,
| | - Ramkumar Sabesan
- Department of Ophthalmology, University of Washington, Seattle, WA, USA
| | | | | | - Peter Unsbo
- Department of Applied Physics, Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Linda Lundström
- Department of Applied Physics, Biomedical and X-Ray Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Austin Roorda
- School of Optometry, University of California, Berkeley, CA, USAVision Science Graduate Group, University of California, Berkeley, CA, USA
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27
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Roorda A, Sabesan R, Schmidt BP, Sincich LC, Tuten WS. Color percepts elicited by stimulation of individual targeted cones. J Vis 2017. [DOI: 10.1167/17.7.25] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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29
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Sabesan R, Schmidt BP, Tuten WS, Roorda A. The elementary representation of spatial and color vision in the human retina. Sci Adv 2016; 2:e1600797. [PMID: 27652339 PMCID: PMC5023317 DOI: 10.1126/sciadv.1600797] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2016] [Accepted: 08/19/2016] [Indexed: 05/05/2023]
Abstract
The retina is the most accessible element of the central nervous system for linking behavior to the activity of isolated neurons. We unraveled behavior at the elementary level of single input units-the visual sensation generated by stimulating individual long (L), middle (M), and short (S) wavelength-sensitive cones with light. Spectrally identified cones near the fovea of human observers were targeted with small spots of light, and the type, proportion, and repeatability of the elicited sensations were recorded. Two distinct populations of cones were observed: a smaller group predominantly associated with signaling chromatic sensations and a second, more numerous population linked to achromatic percepts. Red and green sensations were mainly driven by L- and M-cones, respectively, although both cone types elicited achromatic percepts. Sensations generated by cones were rarely stochastic; rather, they were consistent over many months and were dominated by one specific perceptual category. Cones lying in the midst of a pure spectrally opponent neighborhood, an arrangement purported to be most efficient in producing chromatic signals in downstream neurons, were no more likely to signal chromatic percepts. Overall, the results are consistent with the idea that the nervous system encodes high-resolution achromatic information and lower-resolution color signals in separate pathways that emerge as early as the first synapse. The lower proportion of cones eliciting color sensations may reflect a lack of evolutionary pressure for the chromatic system to be as fine-grained as the high-acuity achromatic system.
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Affiliation(s)
- Ramkumar Sabesan
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
- Corresponding author.
| | - Brian P. Schmidt
- Graduate Program in Neuroscience, University of Washington, Seattle, WA 98109, USA
| | - William S. Tuten
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Austin Roorda
- School of Optometry and Vision Science Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
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Privitera CM, Sabesan R, Winter S, Tiruveedhula P, Roorda A. Eye-tracking technology for real-time monitoring of transverse chromatic aberration. Opt Lett 2016; 41:1728-31. [PMID: 27082330 PMCID: PMC5322945 DOI: 10.1364/ol.41.001728] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Objective measurements of transverse chromatic aberration (TCA) between two or more wavelengths with an adaptive optics scanning laser ophthalmoscope (AOSLO) are very accurate, but frequent measurements are impractical in many experimental settings. Here, we demonstrate a pupil tracker that can accurately measure relative changes in TCA that are caused by small shifts in the pupil relative to the AOSLO imaging beam. Corrections for TCA caused by these shifts improve the measurement of TCA as a function of eccentricity, revealing a strong linear relationship. We propose that pupil tracking be integrated into AOSLO systems, where robust and unobtrusive control of TCA is required.
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Affiliation(s)
| | | | - Simon Winter
- Department of Applied Physics, Biomedical and X-ray Physics, KTH Royal Institute of Technology, Stockholm, Sweden
| | | | - Austin Roorda
- School of Optometry, University of California, Berkeley, CA
- Vision Science Graduate Group, University of California, Berkeley, CA
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Schmidt BP, Sabesan R, Tuten WS, Neitz J, Roorda A. How Does the Brain Interpret Signals from Single Cones? J Vis 2016. [DOI: 10.1167/16.4.46] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Abstract
We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone.
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Affiliation(s)
- Christy K. Sheehy
- Vision Science Graduate Group, University of California, Berkeley; Berkeley, CA 94720, USA
- School of Optometry, University of California, Berkeley; Berkeley, CA 94720, USA
| | - Pavan Tiruveedhula
- School of Optometry, University of California, Berkeley; Berkeley, CA 94720, USA
| | - Ramkumar Sabesan
- School of Optometry, University of California, Berkeley; Berkeley, CA 94720, USA
| | - Austin Roorda
- Vision Science Graduate Group, University of California, Berkeley; Berkeley, CA 94720, USA
- School of Optometry, University of California, Berkeley; Berkeley, CA 94720, USA
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Sabesan R, Tuten WS, Harmening WM, Carney T, Klein SA, Roorda A. Measuring color vision on a cellular scale in an adaptive optics scanning laser ophthalmoscope. J Vis 2013. [DOI: 10.1167/13.15.32] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Klein S, Carney T, Switkes G, Choi M, Roorda A, Privitera C, Sabesan R, Sincich L. Towards the single cone transducer function. J Vis 2013. [DOI: 10.1167/13.15.17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Zheleznyak L, Sabesan R, Oh JS, MacRae S, Yoon G. Modified monovision with spherical aberration to improve presbyopic through-focus visual performance. Invest Ophthalmol Vis Sci 2013; 54:3157-65. [PMID: 23557742 DOI: 10.1167/iovs.12-11050] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the impact on visual performance of modifying monovision with monocularly induced spherical aberration (SA) to increase depth of focus (DoF), thereby enhancing binocular through-focus visual performance. METHODS A binocular adaptive optics (AO) vision simulator was used to correct both eyes' native aberrations and induce traditional (TMV) and modified (MMV) monovision corrections. TMV was simulated with 1.5 diopters (D) of anisometropia (dominant eye at distance, nondominant eye at near). Zernike primary SA was induced in the nondominant eye in MMV. A total of four MMV conditions were tested with various amounts of SA (± 0.2 and ± 0.4 μm) and fixed anisometropia (1.5 D). Monocular and binocular visual acuity (VA) and contrast sensitivity (CS) at 10 cyc/deg and binocular summation were measured through-focus in three cyclopledged subjects with 4-mm pupils. RESULTS MMV with positive SA had a larger benefit for intermediate distances (1.5 lines at 1.0 D) than with negative SA, compared with TMV. Negative SA had a stronger benefit in VA at near. DoF of all MMV conditions was 3.5 ± 0.5 D (mean) as compared with TMV (2.7 ± 0.3 D). Through-focus CS at 10 cyc/deg was significantly reduced with MMV as compared to TMV only at intermediate object distances, however was unaffected at distance. Binocular summation was absent at all object distances except 0.5 D, where it improved in MMV by 19% over TMV. CONCLUSIONS Modified monovision with SA improves through-focus VA and DoF as compared with traditional monovision. Binocular summation also increased as interocular similarity of image quality increased due to extended monocular DoF.
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Affiliation(s)
- Len Zheleznyak
- Institute of Optics, University of Rochester, Rochester, New York 14624, USA.
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Sabesan R, Zheleznyak L, Yoon G. Binocular visual performance and summation after correcting higher order aberrations. Biomed Opt Express 2012; 3:3176-89. [PMID: 23243568 PMCID: PMC3521316 DOI: 10.1364/boe.3.003176] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Revised: 10/03/2012] [Accepted: 10/04/2012] [Indexed: 05/04/2023]
Abstract
Although the ocular higher order aberrations degrade the retinal image substantially, most studies have investigated their effect on vision only under monocular conditions. Here, we have investigated the impact of binocular higher order aberration correction on visual performance and binocular summation by constructing a binocular adaptive optics (AO) vision simulator. Binocular monochromatic aberration correction using AO improved visual acuity and contrast sensitivity significantly. The improvement however, differed from that achieved under monocular viewing. At high spatial frequency (24 c/deg), the monocular benefit in contrast sensitivity was significantly larger than the benefit achieved binocularly. In addition, binocular summation for higher spatial frequencies was the largest in the presence of subject's native higher order aberrations and was reduced when these aberrations were corrected. This study thus demonstrates the vast potential of binocular AO vision testing in understanding the impact of ocular optics on habitual binocular vision.
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Affiliation(s)
- Ramkumar Sabesan
- The Institute of Optics, University of Rochester, Rochester, NY 14627, USA ; Center for Visual Science, University of Rochester, Rochester, NY 14627, USA ; Flaum Eye Institute, University of Rochester, NY 14627, USA
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Pantanelli SM, Sabesan R, Ching SST, Yoon G, Hindman HB. Visual performance with wave aberration correction after penetrating, deep anterior lamellar, or endothelial keratoplasty. Invest Ophthalmol Vis Sci 2012; 53:4797-804. [PMID: 22700712 DOI: 10.1167/iovs.12-10003] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To investigate the contribution ocular aberrations have on visual performance by quantifying improvements in best-corrected visual acuity (VA) and contrast sensitivity (CS) obtained with higher-order aberration (HOA) correction after penetrating (PK), deep anterior lamellar (DALK), or Descemet's stripping automated endothelial keratoplasty (DSAEK). METHODS Sixteen eyes were evaluated from 14 subjects who underwent PK (n = 5), DALK (n = 6), or DSAEK (n = 5) greater than 1 year prior to study enrollment. Ocular aberrations were measured and an adaptive optics system was used to correct ocular lower-order aberration (LOA) and HOA. VA and CS were measured for each subject with LOA or full-aberration correction. CS was measured at each of three spatial frequencies: 4, 8, and 12 cycles/deg. RESULTS All keratoplasty groups had more aberration than that of a normal myopic population and experienced significant VA gains with full-aberration correction (P < 0.0013). PK subjects had better VA than that of DSAEK subjects with LOA correction (logMAR VA 0.03 ± 0.05 vs. 0.25 ± 0.05; P = 0.0870). After HOA correction this trend persisted (P = 0.1734). DSAEK subjects also experienced less VA benefit from full-aberration correction than that of PK and DALK subjects. All keratoplasty groups demonstrated similar CS benefits from full-aberration correction despite differing higher-order root-mean-square magnitudes. CONCLUSIONS PK eyes had better logMAR VA than that of DSAEK eyes with LOA correction, whereas DALK eyes performed intermediate between the two. When full correction was applied, the same trend persisted. The findings suggest that factors other than aberration contribute to decrements in VA with DSAEK compared with PK.
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Affiliation(s)
- Seth M Pantanelli
- David and Ilene Flaum Eye Institute, 601 Elmwood Avenue, Rochester, NY 14642, USA
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Zheleznyak L, Oh JS, Sabesan R, Yoon G. Modifying monovision to improve presbyopic through-focus visual performance with a binocular adaptive optics system. J Vis 2010. [DOI: 10.1167/10.15.38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Yoon G, Sabesan R, Zheleznyak L, So E. Binocular visual performance after correcting higher order aberrations. J Vis 2010. [DOI: 10.1167/10.15.63] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Pantanelli SM, Sabesan R, Cai X, Ching S, Yoon G, Hindman HB. Effect of ocular aberration on visual acuity and contrast sensitivity after penetrating keratoplasty (PK), deep anterior lamellar keratoplasty (DALK), and Descemet's stripping automated endothelial keratoplasty (DSAEK). J Vis 2010. [DOI: 10.1167/10.15.76] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Sabesan R, MacRae S, Yoon G. Role of native spherical aberration in the extended depth of focus. J Vis 2010. [DOI: 10.1167/10.15.74] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Sabesan R, Yoon G. Neural compensation for long-term asymmetric optical blur to improve visual performance in keratoconic eyes. Invest Ophthalmol Vis Sci 2010; 51:3835-9. [PMID: 20130284 PMCID: PMC2904023 DOI: 10.1167/iovs.09-4558] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 12/08/2009] [Accepted: 01/24/2010] [Indexed: 11/24/2022] Open
Abstract
Purpose. To investigate whether long-term visual experience with irregular optical blur compensates for the impact of higher-order aberration on visual performance in keratoconic (KC) eyes. Methods. The aberrations and high (100%)- and low (20%)-contrast tumbling E visual acuity (VA) were measured in four moderate KC eyes in which the subjects were wearing their own prescribed soft toric contact lenses over a 6-mm pupil. VA was measured in three emmetropic normal eyes for comparison with each of the four KC eyes. An adaptive optics system was used to correct the aberration of the normal eye and to induce the aberration of the KC eye simultaneously during vision testing. The magnitude of neural compensation was defined as improvement in VA in each KC eye compared with the normal eyes with KC aberrations. Results. Mean total and higher-order root mean square errors in the KC eyes with contact lenses were 2.72 +/- 0.83 mum and 1.36 +/- 0.29 mum, respectively, for a 6-mm pupil. Residual RMS wavefront error in induction of KC aberrations on normal eyes was approximately 0.1 mum in all cases. Each KC eye had statistically better high (P < 0.02)- and low (P < 0.03)-contrast VA than the three normal eyes. Mean compensation for high-contrast VA in logMAR was 0.12 +/- 0.09, corresponding to an improvement of 23.8%. A similar result was obtained for low-contrast VA. The magnitude of compensation increased with the severity of KC aberrations. Conclusions. In KC eyes, the neural visual system compensates for long-term visual experience with an asymmetrically blurred retinal image, resulting in improved visual performance.
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Affiliation(s)
- Ramkumar Sabesan
- Institute of Optics, University of Rochester, Rochester, New York, USA.
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Sabesan R, Yoon G. Neural compensation to asymmetric optical blur to enhance visual performance in keratoconic eyes. J Vis 2010. [DOI: 10.1167/8.17.78] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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Kalaivani T, Undre P, Sabesan R, Krishnan S. Dielectric relaxation studies of aqueous sodium dodecyl sulfate with some amines as co-solvents by time domain reflectometry technique. Main Group Chemistry 2009. [DOI: 10.1080/10241220902977646] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Sabesan R, Yoon G. Visual performance after correcting higher order aberrations in keratoconic eyes. J Vis 2009; 9:6.1-10. [PMID: 19757884 DOI: 10.1167/9.5.6] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2008] [Accepted: 02/10/2009] [Indexed: 11/24/2022] Open
Abstract
Keratoconic eyes are affected by an irregular optical blur induced by significant magnitude of higher order aberrations (HOAs). Although it is expected that correction of ocular aberrations leads to an improvement in visual performance, keratoconic eyes might not achieve the visual benefit predicted by optical theory because of long-term adaptation to poor retinal image quality. To investigate this, an adaptive optics (AO) system equipped with a large-stroke deformable mirror and a Shack-Hartmann wavefront sensor was used to correct the aberrations and measure high contrast tumbling E visual acuity (HCVA) in 8 keratoconic eyes. Eight normal eyes were employed as control. Aberrations were dynamically corrected with closed-loop AO during visual acuity testing, with residual root-mean-square error of around 0.1 microm in both groups over 6-mm pupil (p = 0.11). With AO correction, the HCVA in logMAR was -0.26 +/- 0.063 in normal eyes, and in keratoconic eyes, it was -0.07 +/- 0.051 (p = 0.0001) for the same pupil size. There was no correlation in the AO-corrected HCVA for normals with the magnitudes of their native HOA. However, within keratoconic eyes, poorer AO-corrected HCVA was observed with an increase of the native magnitudes of HOA (R(2) = 0.67). This may indicate that long-term visual experience with poor retinal image quality, induced by HOA, may restrict the visual benefit achievable immediately after correction in keratoconic eyes.
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Affiliation(s)
- Ramkumar Sabesan
- Institute of Optics, University of Rochester, Rochester, NY, USA.
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Sakthivel B, Sabesan R. Dielectric studies of self-assembling amphiphiles: Part II: Microwave dielectric relaxation of long chain amphiphilic acids and alcohols. J Mol Liq 2007. [DOI: 10.1016/j.molliq.2007.02.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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