Examining oculomotor behavior in central vision loss with a gaze-contingent display.

Patients with central vision loss due to macular degeneration (MD) must rely on their peripheral vision for tasks normally performed by the fovea. Many patients develop a preferred retinal locus (PRL), an eccentric retinal location used as a substitute for the damaged fovea in tasks such as face recognition, navigation, and reading. However, the mechanisms underlying PRL development remain elusive, and no single hypothesis fully explains its characteristics. Investigations into PRL development are hindered by oculomotor assessments, which often focus on fixation ability while neglecting other eye movement characteristics and potentially conflating different behaviors over time. In previous work, we introduced a series of oculomotor metrics in cases of simulated central vision loss, demonstrating that complex profiles of eye movement behavior can be extracted from a simple visual task. Here we present longitudinal data from 10 patients with MD as evidence of the feasibility of using these metrics to characterize different profiles of eye movements following central vision loss. Consistent with findings in healthy individuals using artificial scotoma, the metrics reveal substantial individual differences in behavior, both at baseline and after visual training. Overall, patients exhibit significantly higher saccadic re-referencing than controls, despite larger inter-individual differences. These metrics provide a detailed evaluation of oculomotor behavior in patients with central vision loss and offer a valuable tool for assessing progress in training protocols.