Abstract
To evaluate the contribution of fixational eye movements to dynamic aberration, 50 healthy eyes were examined with an original custom-built Shack-Hartmann aberrometer, running at a temporal frequency of 236Hz, with 22 lenslets across a 5mm pupil, synchronized with a 236Hz pupil tracker. A comparison of the dynamic behavior of the first 21 Zernike modes (starting from defocus) with and without digital pupil stabilization, on a 3.4s sequence between blinks, showed that the contribution of fixational eye movements to dynamic aberration is negligible. Therefore we highlighted the fact that a pupil tracker coupled to an Adaptive Optics Ophthalmoscope is not essential to achieve diffraction-limited resolution.
Highlights
Imaging the human retina at high-resolution has an important impact on early-stage retinal disease diagnosis and treatment as well as in monitoring the effects of new drugs and improving our understanding of the eye [1, 2]
Using previously published data [5] of high-temporal resolution characterization of ocular aberrations synchronised with pupil displacement on a population of 50 healthy eyes, we presented a comparison of the dynamic behavior of the first 21 Zernike modes, with and without digital pupil stabilization, on a 3.4s sequence between blinks
Our results showed a major correlation between dynamic aberration and two fixational eye movements: fast horizontal micro-saccades and large amplitude horizontal drifts
Summary
Imaging the human retina at high-resolution has an important impact on early-stage retinal disease diagnosis and treatment as well as in monitoring the effects of new drugs and improving our understanding of the eye [1, 2]. Such high-resolution retinal images can be obtained using Adaptive Optics (AO) systems [3]. Fixational eye movements [6, 7], tear film dynamics [8,9,10] and micro-fluctuations of accommodation [11, 12] were identified as important sources of temporal variation of ocular aberration. Fixational eye movements exhibit three main components [13]: 1) tremors, a wave-like motion of small amplitude (≈ diameter of a cone in the fovea) but high frequency (≈ 90 Hz); 2) drifts, slow movements (0.5deg/s) that carry the eye away from the fixation target (can move across dozens of photoreceptors) and 3) micro-saccades, fast (≈ 20ms in duration), jerk-like movements (10-100deg/s) to correct from drifts and from Troxler fading [14]
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