Can retinal eccentricity predict visual acuity and contrast sensitivity at the PRL in AMD patients?

Abstract

Most patients with age-related macular degeneration (AMD) and bilateral central scotomas adopt a preferred retinal locus (PRL) for eccentric viewing. It is postulated that the optimal PRL position is inferior visual space as it provides a larger uninterrupted visual span for reading and mobility. However, the majority of patients place their PRL to the left of their scotoma in visual field space. The purpose of this study was to investigate which factors determine PRL location and specifically, whether the PRL develops in the area of peripheral retina with best visual acuity (VA) and contrast sensitivity (CS). 24 patients were recruited. They were tested on a scanning laser ophthalmoscope to identify the PRL in their better eye. An eyetracker was used to assess peripheral VA and CS. In 19 patients, the PRL was located near the area of best VA. In only 11 patients, the PRL was located near the area of best CS. Patients had worse VA and CS at their PRLs compared to normal vision subjects. VA was best near the PRL, but this was not the case for CS. We cannot distinguish whether the PRL develops at the area of best VA or if it improves at the PRL through practice.