Optical coherence tomographic parameters as objective signs for visual acuity in patients with retinitis pigmentosa, future candidates for retinal prostheses

Abstract

To find optical coherence tomographic parameters related with visual acuity, and, thus, which might be used as objective signs to predict visual acuity after future treatment, for example retinal prosthesis implantation, 86 eyes of 45 consecutive patients with retinitis pigmentosa, who showed no macular diseases, underwent optical coherence tomography to measure macular retinal thickness and peripapillary retinal nerve fiber layer (RNFL) thickness, and to obtain horizontal cross-sectional images at the fovea for observation of the inner segment/outer segment (IS/OS) junction line. Best-corrected visual acuity was significantly better either in the right eyes or in the left eyes with greater retinal thickness of all four quadrants of the macular area in the inner ring, encompassing 1-3mm from the foveal center (P<0.05, Spearman rank correlation test), and also with the presence of the IS/OS line at the fovea (P<0.0001, Wilcoxon-Kruskal-Wallis rank sum test). Retinal average thickness in the posterior pole covering the 6×6mm square area was positively correlated with peripapillary RNFL average thickness either in the right eyes or in the left eyes (P<0.05). The average thickness of the peripapillary RNFL became significantly less with age (P<0.05), but was not related with visual acuity. Macular retinal thickness and the presence of the IS/OS line, but not peripapillary RNFL thickness, could serve as objective signs for better visual acuity in retinitis pigmentosa. The macular retinal thickness might be used as an objective predictor to choose patients with retinitis pigmentosa who would be expected to gain vision after retinal prosthesis implantation.