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Stephen A Burns, Ting Luo; Dual Scan AOSLO Imaging for measuring eye velocity and correcting eye motion distortion of images.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):661.
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© ARVO (1962-2015); The Authors (2016-present)
To develop and perform initial evaluation of a new algorithm for measuring and correcting eye movements during AOSLO Imaging.
A dual channel two wavelength Adaptive Optics Scanning Laser Ophthalmoscope (780 and 820 nm) was used. Light from the two wavelengths enter the eye at slightly different angles, imaging the same retinal at slightly different times. The two beams were separated on the retina by approximately 36 lines. This corresponds to a time differential of approximately 2.3 msec and a spatial displacement of approximately 36 microns. Eye motion is measured based on the fact that pairs of lines are collected from the retina simultaneously, and thus are not susceptible to eye movement distortion. Displacements between the same retinal locations therefore represent the displacement due to eye motion during the 2.3 msec interval and thus are a direct measurement of the motion during this interval. From these displacements a complete eye movement velocity trace for within frame motions can be computed at micron level accuracy. Integration of the velocity profiles allows removing the impact of eye motions on each image frame.Series of images of 100 sequential frames at a series of adjacent retinal positions were obtained in 3 subjects.
In all subjects the impact of eye movements could be substantially decreased making almost all frames in each of 100 video frame acquisitions useable. Exceptions occurred for large saccades, especially at the top and bottom of image frames where succeeding data were not available.Reconstruction of non-distorted image sequences allowed essentially all frames to be averaged.
This approach allows direct estimation of eye velocity during imaging. It also holds promise for generating retinal images without the impact of eye movements. The primary limitations of the current implementation arise from slight changes in transverse chromatic aberration from one retinal location to another, as well as the need to decrease small errors in location which can accumulate when integrating the change in eye positon.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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