An eye movement technique for correlating fixational target eye movements with location on the retinal image

Recent investigation demonstrate that ocular motility in eyes with retinal pathology may show a lower propensity to visit such areas of the retina as compared to non-pathological retinal sites. While current ophthalmic instruments with the ability to image both the retina and visual function test target placement on the retina have provided this observation, the ability to quantify in real time these images as an eye movement measurement is presently lacking and the objective of this paper. A Rodenstock confocal scanning ophthalmoscope (CSLO) was used to image the retina during the performance of a visual fixation task. Direct observation of acuity target placement at the retina under continuous viewing conditions was possible with this apparatus. Target fixation eye movement images of the retina were rapidly digitized from video tape records and registered using a specialized rapid retinal image tracking algorithm. Fixational eye movement pattern densities at the retina were derived from these data. Preliminary data obtained demonstrate the utility of this technique in quantifying fixation eye movement patterns observed in three human patients with vocation-related laser retinal injury. In all patients, areas of severe retinal damage was generally avoided. The density of ocular eye movement tends to reflect regions of retinal normality and avoidance of retinal regions with severe pathology. Variation in eye movement density may exist where pathology is less severe.