Abstract
Purpose: :
In RP patients degenerative process could interfere with a retinal correct development at highest level of binocular cooperation: tridimensional perception. These alterations seemed to be correlated to the presence of macular impairment. The aim of this study is to evaluate macular function loss that cause alteration in stereo acuity (SA).
Methods: :
We studied 23 patients affected with primary RP age 30.34 ±10.27 years, selected with BCVA higher than 0.7 mean 0.911±1.42, and a control group of 23 age and sex matched healthy patients. All of them underwent to a complete ophthalmological observation, Wirth, Lang, TNO stereo tests and Microperimetry (Nidek MP–1); results were analyzed by Varimax factor Analysis.
Results: :
Mean SA in RP group was of 136.52±26.5 (Wirt) while in the control group was 67.2±11.5 Lang SA in RP group was of 391.39±53.72 while in the normal group was 1150±33.4"; TNO SA in the RP group was of 69.3±14.39 while in the control group was 15.97±3.7. Factor analysis in RP showed significant correlation between SA and VA (p=0.0001). But this correlation was not found in the control group (p=0.912). Microperimetric analisys showed a significative interocular difference in single point retinal sensitivity and in fixation stability (p=0.027). In the RP patients SA loss resulted significantly correlated (p=0.0129) to the cohesistence of one or more macular alteration like atrophy, Vitreoretinal interface wrinkling or cystoid macular edema.
Conclusions: :
Progressive RP degeneration could determine impairment of binocular vision due to anomalous retinal correspondence as demonstrated by retinal sensitivity differences and consequebtly incomplete Panum’s area use, causing an incongruent retinal localization. This is confirmed by dissociating tests as the Lang or TNO. Positive correlation between VA and SA demonstrates a wrong image analysis and a lowering in resolution power that damage stereoscopic perception, according Burian and Fishman studies on Vernier’s acuity, showing that this may be due to a photoreceptor random loss.
Keywords: retinal degenerations: hereditary • binocular vision/stereopsis • neuro-ophthalmology: cortical function/rehabilitation