Abstract: Objective To investigate the spatial processing in patients with retinal pigmentosa (RP) in the central and peripheral visual fields by diffusion model analysis. Methods A total of 19 RP patients and 13 healthy controls were recruited in this study. The spatial processing task was aimed to evaluate the spatial processing in the peripheral and central visual fields with various field sizes. Reaction times (RTs), accuracies (ACCs) were recorded. In addition, the EZ-diffusion model analysis was performed for possible underlying mechanism. Results Compared with the control group [for large: (768±65) ms; for medium: (736±56) ms], RP group reacted slower in peripheral visual field including large (1193±106) ms and medium (1059±84) ms stimulus (for large: P<0.01; for medium: P<0.01). The diffusion model showed that smaller v (drift rate) (0.20±0.02) cv in large stimulus than control group (0.27±0.03) cv (P<0.05); and for large (540±44) ms, medium (556±37) ms, small (516±47) ms stimulus, the Ter (nondecision time) was found longer (for large: P<0.001, for medium: P<0.01, for small: P<0.001) than control group [for large: (286±59) ms, for medium: (358±31) ms, for small: (211±64) ms]. Conclusions RP exerts a visual field loss-related impairment in spatial cognition mainly in the peripheral visual field, which might be attributable to the decrease in information processing speed and increase in information encoding time.

Key words: Retinal pigmentosa, Diffusion model, Peripheral visual field, Central visual field, Information processing