Applications For Eye–Motion–Corrected Adaptive Optics Scanning Laser Ophthalmoscope Videos

Abstract

Purpose: : Retinal motion traces extracted from the local distortions within adaptive optics scanning laser ophthalmoscope video frames facilitates (i) very accurate and high speed tracking of eye movements; (ii) stabilization of AOSLO videos; (iii) the ability to co–add a series of single frames to reduce noise effects; and (iv) the ability to form image montages.

Methods: : Fixational eye motion is estimated from sequences of frames of AOSLO video data using a patch–based cross correlation scheme (described in detail in Vogel et al, Optics Express, in press). AOSLO data is processed off–line using the GetMotion software package, which is custom–written in MATLAB^TM. A real–time implementation is currently under development.

Results: : Off–line retinal motion estimates with the GetMotion package are possible on segments of most AOSLO videos. Eye motion traces from one video were validated against a simultaneously–recorded motion trace that was recorded with a dual–purkinje eye tracker (Fourward Technologies, Buena Vista VA). In the stabilized video, image motion is stabilized to a fraction of a minute of arc, which is less than the size of a cone photoreceptor near the fovea. Eye motion traces are recorded with frequencies as high as 480 Hz. Co–added frames of stabilized AOSLO video reveal high signal–to–noise images of the contiguous retinal cone mosaic. High resolution montages extracted from panning videos are also possible.

Conclusions: : In high magnification AOSLO images, distortion of frames due to eye motion can be corrected. The outcomes of the distortion correction are high frequency eye traces, stabilized video, and high signal–to–noise images, including montages of extended retinal regions. Real–time on–line eye position measurements from an enhanced algorithm might be used to guide precision placement of stimuli or treatment lasers on the retina. Development of these enhanced algorithms are still underway.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • image processing • eye movements