Foveolar drusen decrease fixation stability in pre-symptomatic AMD

Abstract

PurposeWe conducted a clinical study to characterize fine spatiotemporal alterations of FEM in controls and patients with pre-clinical signs of age-related macular degeneration (AMD).MethodsTwenty-seven participants were recruited from the SilverSight cohort of the Vision Institute - Quinze-Vingts National Vision Hospital, Paris. Subjects were included in three groups: healthy young, healthy aging controls, and aging subjects with drusen. Detection of microdrusen was done using gaze-dependent adaptive optics ophthalmology. Monocular retinal tracking was based on adaptive optics flood illumination ophthalmoscopy (AO-FIO). The system allows for sub-arcminute resolution, high-speed, distortion-free imaging of the foveal area. Local stimulation through digital micromirror (DMD) projection from a near infrared source enabled projection of optotypes. Eye movements were estimated using a phase-correlation registration algorithm.ResultsCompared to controls, patients with foveal drusen showed higher microsaccade amplitude, higher drift diffusion coefficient, and worse fixation stability -i.e. higher isoline area. Among the drusen group, the increase of microsaccade amplitude and ISOA was correlated with drusen eccentricity; the closer the drusen were to the center of the fovea, the more unstable were FEM.ConclusionsWe demonstrate the clinical interest of a novel high-precision retinal tracking technique to characterize FEM changes at the microscopic level. We found significant differences between the drusen group and both healthy young and older adult groups. Central drusen altered fixation stability characteristics, resulting in compensatory FEM changes. High speed, high resolution FEM analysis may help to define the functional signatures of early age-related changes.

Real-time optical stabilization of retinal motion at micrometer precision using Adaptive Optics Flood-Illumination Ophthalmsocope

“…In addition, precise delivery of visual stimuli for photostimulation or laser strikes for photocoagulation surgery may be possible in patients with poor fixation. Furthermore, the proposed algorithm, which is robust to noisy images, can be used to estimate eye movements during psychophysical testing and may help to find early signs of retinal diseases by characterizing fixational eye movements [6].…”

“…AO technology has opened new avenues for earlier diagnosis and better treatment of retinal diseases, as well as a better understanding of the normal and diseased retina [2]. Indeed, applications such as cellular imaging of retinal neurons, super-resolution structured illumination [3], functional assessment by cell-targeted photostimulation [4], cellular psychophysical testing [5,6], and high-precision laser photocoagulation surgery [7] benefit from AO's ability to achieve micrometer resolution. However, the improved spatial resolution afforded by the use of AO also makes these applications more sensitive to the effect of constant, involuntary eye movements, even during careful fixation [8,9].…”