Relative locations of macular scotomas near the PRL: effect on low vision reading

Abstract

Patients referred for low vision rehabilitation had Minnesota Reading Acuity (MNRead), visual acuity (VA), and scanning laser ophthalmoscope (SLO) macular function testing performed in their initial evaluation to determine whether dense macular scotomas near the preferred retinal locus (PRL) have a significant effect on the characteristics of reading based on rate. The 99 subjects had macular scotoma characteristics relative to the fovea/PRL of: 22% only to the right; 15% only to the left; 26% both the right and left; 19% above or below; 17% had no dense scotomas. Reading performance (maximum reading speed, critical print size, and reading acuity) was significantly different between the non-scotoma group and all of the scotoma groups. There was no statistically significant difference in the characteristics of reading based on rate between the four scotoma groups: within each there was a wide variation in the characteristics of reading based on rate not fully explained by either VA or scotoma location. The position of the scotoma relative to the PRL was not a statistically significant factor in determining reading rate as found in studies on normally sighted people with artificial scotomas. Other factors (e.g., maybe PRL ability in fixation and saccadic eye movements and/or cognitive ability) are significantly involved in determining reading rate characteristics in people with macular scotomas.