Abstract
Adaptive optics optical coherence tomography (AO-OCT) is a highly sensitive and noninvasive method for three dimensional imaging of the microscopic retina. Like all in vivo retinal imaging techniques, however, it suffers the effects of involuntary eye movements that occur even under normal fixation. In this study we investigated dynamic retinal tracking to measure and correct eye motion at KHz rates for AO-OCT imaging. A customized retina tracking module was integrated into the sample arm of the 2nd-generation Indiana AO-OCT system and images were acquired on three subjects. Analyses were developed based on temporal amplitude and spatial power spectra in conjunction with strip-wise registration to independently measure AO-OCT tracking performance. After optimization of the tracker parameters, the system was found to correct eye movements up to 100 Hz and reduce residual motion to 10 µm root mean square. Between session precision was 33 µm. Performance was limited by tracker-generated noise at high temporal frequencies.
Highlights
Spectral-domain optical coherence tomography with adaptive optics (AO-OCT) is a highly sensitive in vivo method for three dimensional imaging of the living microscopic retina [1,2,3,4,5,6,7,8,9,10,11,12]
We developed analyses based on temporal amplitude and spatial power spectra in conjunction with a strip-wise registration method to measure and optimize tracker performance for Adaptive optics optical coherence tomography (AO-OCT) imaging
The two representative sessions depict with and without tracking, and contain similar levels of eye motion.With tracking, the yellow arrow - pointing to the same location on a vasculature shadow – is present in all frames and appears visually stationary across images
Summary
Spectral-domain optical coherence tomography with adaptive optics (AO-OCT) is a highly sensitive in vivo method for three dimensional imaging of the living microscopic retina [1,2,3,4,5,6,7,8,9,10,11,12]. OCT provides ultrahigh axial resolution using broadband light sources and exquisite sensitivity for detection of faint reflections from essentially any layer in the retina. Eye movements pose two principal challenges for cellular level imaging: (1) image blur and distortion that diminish the visibility of retinal structures captured in individual images and (2) difficulty to track the same structures across images. The latter is challenging for functional studies in which images are captured over extended time intervals
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