Reduced retinal sensitivity and stereopsis in retinitis pigmentosa.

Aim of the study: To compare retinal sensitivity and stereo-acuity (SA) in retinitis pigmentosa (RP). Methods: We studied 23 patients with RP: mean age 30.34± 10.27 years, BCVA better than 0.15 logMAR, and a control group of 23 age and sex matched healthy patients. Every patient underwent a complete ophthalmologic examination, Titmus, Lang, TNO stereo-tests and microperimetry (MP-1, Nidek Technologies). Results were subjected to factor analysis using Varimax rotation. p values < 0.05 were considered statistically significant. Results: With the Titmus stereo test mean SA was 136.52±26.5 in RP group and 67.2±11.5 in the control group; Lang SA was 391.39±53.72 in RP group and 1150±33.4 in the control group; TNO SA was 69.3±14.39 in the RP group and 15.97±3.7in the control group. Factor analysis showed significant correlation between VA and SA (p=0.0001) in RP group. Microperimetry demonstrated that in RP patients inter-ocular difference in retinal sensitivity and fixation stability are related to anomalous stereopsis. p values < 0.05. Conclusion: Progressive RP degeneration could determine impairment of binocular vision due to anomalous inter-ocular retinal sensitivity and incomplete Panum’s area utilization, causing an incongruent retinal localization. This is probably why RP patients with a central retinal involvement, even if minimal, perceive a damaged stereoscopic perception that produce a severe disability.