Purpose: To evaluate scotopic retinal organization in retinopathy of prematurity (ROP) through a study of spatial summation.
Methods: Thresholds for a range of stimulus diameters (0.4°-10°) were measured using a two alternative, spatial, forced choice psychophysical procedure. The critical diameter (DCRIT) for complete summation was estimated in subjects with a history of severe ROP (N = 7) and mild ROP (N = 17). Subjects who were born preterm and never had ROP (N = 16) and term-born subjects (N = 7) were also tested. The subjects ranged in age from 9 to 17 (median 13.5) years.
Results: Critical diameter for complete spatial summation was significantly larger in ROP subjects than in subjects who never had ROP and in term-born control subjects. Critical diameter varied significantly with severity of ROP.
Conclusions: The larger DCRIT values in ROP are consistent with altered organization of the post receptor retina. This may offer the ROP retina a strategy for achieving noise reduction and good dark-adapted visual sensitivity.
Keywords: psychophysics; retinopathy of prematurity; scotopic sensitivity; spatial summation.
Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.