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Wei F, Li CY, Hagan K, Stinnett SS, Kuo AN, Izatt JA, Dhalla AH. Spiral scanning improves subject fixation in widefield retinal imaging. OPTICS LETTERS 2024; 49:2489-2492. [PMID: 38691751 PMCID: PMC11068122 DOI: 10.1364/ol.517088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 04/02/2024] [Indexed: 05/03/2024]
Abstract
Point scanning retinal imaging modalities, including confocal scanning light ophthalmoscopy (cSLO) and optical coherence tomography, suffer from fixational motion artifacts. Fixation targets, though effective at reducing eye motion, are infeasible in some applications (e.g., handheld devices) due to their bulk and complexity. Here, we report on a cSLO device that scans the retina in a spiral pattern under pseudo-visible illumination, thus collecting image data while simultaneously projecting, into the subject's vision, the image of a bullseye, which acts as a virtual fixation target. An imaging study of 14 young adult volunteers was conducted to compare the fixational performance of this technique to that of raster scanning, with and without a discrete inline fixation target. Image registration was used to quantify subject eye motion; a strip-wise registration method was used for raster scans, and a novel, to the best of our knowledge, ring-based method was used for spiral scans. Results indicate a statistically significant reduction in eye motion by the use of spiral scanning as compared to raster scanning without a fixation target.
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Affiliation(s)
- Franklin Wei
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Claire Y. Li
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Kristen Hagan
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Sandra S. Stinnett
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27708, USA
| | - Anthony N. Kuo
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27708, USA
| | - Joseph A. Izatt
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27708, USA
| | - Al-Hafeez Dhalla
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
- Department of Ophthalmology, Duke University Medical Center, Durham, NC 27708, USA
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Bowers NR, Gautier J, Lin S, Roorda A. Fixational eye movements in passive versus active sustained fixation tasks. J Vis 2021; 21:16. [PMID: 34677574 PMCID: PMC8556553 DOI: 10.1167/jov.21.11.16] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Human fixational eye movements are so small and precise that high-speed, accurate tools are needed to fully reveal their properties and functional roles. Where the fixated image lands on the retina and how it moves for different levels of visually demanding tasks is the subject of the current study. An Adaptive Optics Scanning Laser Ophthalmoscope (AOSLO) was used to image, track and present a variety of fixation targets (Maltese cross, disk, concentric circles, Vernier and tumbling-E letter) to healthy subjects. During these different passive (static) or active (discriminating) tasks under natural eye motion, the landing position of the target on the retina was tracked in space and time over the retinal image directly with high spatial (<1 arcmin) and temporal (960 Hz) resolution. We computed both the eye motion and the exact trajectory of the fixated target's motion over the retina. We confirmed that compared to passive tasks, active tasks elicited a partial inhibition of microsaccades, leading to longer drift periods compensated by larger corrective saccades. Consequently, the overall fixation stability during active tasks was on average 57% larger than during passive tasks. The preferred retinal locus of fixation was the same for each task and did not coincide with the location of the peak cone density.
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Affiliation(s)
- Norick R Bowers
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
| | - Josselin Gautier
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
| | - Samantha Lin
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
| | - Austin Roorda
- Herbert Wertheim School of Optometry and Vision Science, University of California, Berkeley, CA, USA.,
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Westheimer G. Focused and defocused retinal images with Bessel and axicon pupil functions. JOURNAL OF THE OPTICAL SOCIETY OF AMERICA. A, OPTICS, IMAGE SCIENCE, AND VISION 2020; 37:108-114. [PMID: 32118886 DOI: 10.1364/josaa.37.000108] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/21/2019] [Indexed: 06/10/2023]
Abstract
Retinal image light distributions in a standard optical model of a diffraction-limited eye with round pupils are presented for several patterns of amplitude and phase modulation of the light admitted into the eye. Of special interest are circularly symmetrical configurations of truncated Bessel amplitude transmission functions, and of light subjected to axicon deviation. It is shown by several examples that this kind of beam shaping allows generation of retinal imagery, which can be more robust to defocus while maintaining minimal image degradation, and it points to situations of two separate zones simultaneously in sharp focus, several diopters apart.
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