Closed-loop optical stabilization and digital image registration in adaptive optics scanning light ophthalmoscopy.

Qiang Yang,Austin Roorda,Ethan A Rossi,David R Williams,Koji Nozato,Jie Zhang,Kenichi Saito

doi:10.1364/boe.5.003174

Abstract

Eye motion is a major impediment to the efficient acquisition of high resolution retinal images with the adaptive optics (AO) scanning light ophthalmoscope (AOSLO). Here we demonstrate a solution to this problem by implementing both optical stabilization and digital image registration in an AOSLO. We replaced the slow scanning mirror with a two-axis tip/tilt mirror for the dual functions of slow scanning and optical stabilization. Closed-loop optical stabilization reduced the amplitude of eye-movement related-image motion by a factor of 10-15. The residual RMS error after optical stabilization alone was on the order of the size of foveal cones: ~1.66-2.56 μm or ~0.34-0.53 arcmin with typical fixational eye motion for normal observers. The full implementation, with real-time digital image registration, corrected the residual eye motion after optical stabilization with an accuracy of ~0.20-0.25 μm or ~0.04-0.05 arcmin RMS, which to our knowledge is more accurate than any method previously reported.

Highlights

The adaptive optics scanning light ophthalmoscope (AOSLO) has become an important tool for the study of the human retina in both normal and diseased eyes [1,2,3,4]
Fixational eye motion causes unique distortions in each AOSLO frame due to the fact that each image is acquired over time
Modern dual-Purkinje image (DPI) eye trackers can measure eye motion and manipulate visual stimuli with a precision of ~1 arcmin [23]. Each of these methods can only indirectly infer the motion of the retinal image; here we report on recent advances to measure and stabilize eye motion by directly tracking the motion of the retina itself

Summary

Introduction

The adaptive optics scanning light ophthalmoscope (AOSLO) has become an important tool for the study of the human retina in both normal and diseased eyes [1,2,3,4]. In patients with retinal disease or poor vision, fixational eye movements can be amplified [7] and introduce distortions that are a major hindrance to efficient AOSLO imaging, in some cases precluding imaging altogether. These patients are potentially some of the most interesting to study using this technology. For clinical imaging, to minimize or eliminate this motion altogether

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