R A Schuchard¹, D C Fletcher²
¹Veterans Affairs, Rehab R&D Center, Decatur, GA, United States; ²University of Alabama Birmingham, Ophthalmology, Birmingham, AL, United States
Background. This study was done to determine the PRL ability in fixation, saccade, and pursuit as a function of retinal eccentricity location of the PRL.
Methods. 211 eyes of 115 people with macular scotomas were evaluated with the scanning laser ophthalmoscope for PRL characteristics (location and eye movement ability) and with the ETDRS for visual acuity.
Results. The visual acuity range was from 20/50 to 20/3800 (monocular; median = 20/400). Distance from the fovea to the PRL centers were 0.0 to 25.8 degrees (median = 4.0 degrees). PRL diameter was from 1.0 to 9.0 degrees (median = 3.0 degrees). Regression analysis gave the following results: 1) fixation diameter by eccentricity (r squared = 0.48); 2) Visual acuity by eccentricity (r squared = 0.31); 3) Fixation diameter by visual acuity (r squared = 0.12); 4) Saccade ability by eccentricity (r squared = 0.18); 5) Pursuit ability by eccentricity (r squared = 0.20); 6) Saccade ability by visual acuity (r squared = 0.13); and 7) Pursuit ability by visual acuity (r squared = 0.16).
Conclusions. Prl location relative to the fovea was related to eye movement performance. PRLs at or near the fovea displayed the widest range of performance variability while more eccentric PRLs had lower ability and were more uniform in performance. In people with macular diseases/scotomas, lower acuity does not necessarily indicate a PRL more distant from the fovea as near foveal PRLs can have poorer performance (visual acuity and eye movement) due to yet unknown factors. It is a mistake to assume that all patients with a low visual acuity due to macular diseases need to be taught eccentric viewing techniques. It is also an incorrect assumption that all patients with foveal function have good eye movement performance.
Return to the ISLRR.ORG Home Page
