Optical Coherence Tomography In Retinitis Pigmentosa Patients Study - 5 Years Follow Up

Abstract

Purpose: : To study OCT findings (to compare and correlate retinal nervous fiber layer-RNFL and retinal thickness) and visual acuity in retinitis pigmentosa (RP) patients and to study part of the same group of patients in 5 years follow up.

Methods: : This study was approved by the UNIFESP medical research ethical committee. Twenty nine RP eyes were examined. Twenty five RP eyes had visual acuity better than 20/800. OCT (Fast RNFL Thickness Scan 3,4mm protocol) scans, complete eye exam and electrophysiological tests (full-field electroretinogram and dark adaptation threshold test) were performed. After five years, seven eyes were reexamined with OCT. The OCT scans were analyzed with the caliper tool under the RNFL thickness single eye protocol. Statistical analysis was performed (Newman-Keuls multiple comparison test, student t-test and Pearson correlation) with the SPSS version 12.0 software.

Results: : The electroretinogram confirmed RP diagnosis in the studied patients. There was a reverse correlation between visual acuity and retinal thickness in the temporal quadrant, and this correlation was stronger when considering RP eyes with visual acuity better than 20/800 (r=0.64; p<0.001). There was no correlation between visual acuity and RNFL thickness. The nasal quadrant was thinner than the other quadrants (retina and RNFL) in RP patients. The five years follow up showed that retinal thickness increases over time in the temporal quadrant (35.95um; p<0.001) and also increases when considering the nasal and superior quadrant and the general mean.

Conclusions: : RP eyes showed thicker retina in the temporal quadrant as the visual acuity decreases. Also the retina becomes thicker over time when considering a five years follow up. Both data support the hypothesis that as the degeneration progresses and becomes more severe the retina becomes thicker. The data show that the increase in retinal thickness and its layers during a retinal treatment in RP patients may not be a sign of improvement. Retinal thickness may be a parameter to be used to evaluate the degeneration progress in patients with better visual acuity. Also this parameter may be developed to be used to select patients to future treatments (as retinal prosthesis or neuroprotector agents in retinal diseases).

Keywords: retina • degenerations/dystrophies • imaging/image analysis: clinical