Reversibly Desensitising the Human Retina to Delay Saccadic Reaction Time for Diagnostic Prototyping

Glaucoma is a progressive retinal disease and a leading cause of blindness. Early detection is crucial but challenging due to subtle symptoms and the burden of standard clinical tests. Standard Automated Perimetry, though the gold standard for detecting glaucomatous functional deficits, is time-consuming and demanding for patients. Eye-movement perimetry (EMP) offers a promising alternative by using saccadic reaction times as indirect markers of visual-field integrity. However, EMP development is impeded by the need for large trial numbers due to inherent reaction-time variability and ethical constraints on patient involvement in early-stage prototyping. To address these limitations, this study employed photopigment bleaching to develop a method for generating reaction-time delays typically associated with glaucoma. Specific retinal regions in healthy participants were desensitised transiently using non-harmful light patterns displayed on a standard monitor. Participants performed an oculomotor task with targets presented at locations across the visual field either with or without desensitisation. Saccadic reaction times (target onset to movement onset) were measured to quantify the behavioural effect of desensitisation. Localised desensitisation significantly increased the mean (50-130 ms) and variability (20-60 ms) of saccadic reaction times in desensitised regions, and could lead to detection deficits resembling scotomas. These effects were more pronounced at greater eccentricities, consistent with retinal heterogeneity in photoreceptor density and receptive-field size, and decayed within hundreds of milliseconds (250-600 ms). This approach offers a safe, transient and spatially specific method for inducing reaction-time delays across the visual field in healthy individuals, enabling efficient prototyping of EMP paradigms prior to patient testing.