Reading Performance Is Reduced by Parafoveal Scotomas in Patients with Macular Telangiectasia Type 2

Abstract

PURPOSE: Macular telangiectasia (MacTel) type 2 typically exhibits sharply demarcated parafoveal scotomas. In an investigation of their significance for reading performance, reading acuity and speed were measured and correlated with parafoveal sensitivity and fixation stability. METHODS: In this prospective controlled cross-sectional observational study, 49 eyes of 26 patients with MacTel type 2 were investigated. Twenty-four eyes of 14 age-matched normal subjects served as the control. Reading acuity and reading speed (in words per minute [wpm]) were assessed by Radner charts. Retinal sensitivity was measured using fundus controlled microperimetry (MP1; Nidek Technologies). Fixation stability was quantified by the bivariate contour ellipse area (BCEA). Multiple logistic regression analysis was used to delineate outcome predictors of reading acuity and speed. RESULTS: Mean reading speed was considerably reduced in patients (to 141 wpm; control speed, 190 wpm; P < 0.001) as was reading acuity (patients, 20/63; control subjects, 20/32; P < 0.001). Mean best corrected visual acuity (BCVA) was reduced in most eyes (patients, 20/50; control subjects, 20/20; P < 0.001). Mean BCEA was not reduced compared with that in the control subjects. BCVA reduction predicted reading acuity loss (P = 0.02) and a decrease in maximum reading speed (P < 0.001). Parafoveal sensitivity loss resulted in decreased reading acuity (P = 0.03) and reading speed reduction (P < 0.001). CONCLUSIONS: These findings indicate that parafoveal sensitivity loss in MacTel type 2 is associated with loss of reading performance despite stable central fixation. Reading performance appears to be a sensitive variable of functional impairment in MacTel type 2 and should therefore be considered an outcome measure in future interventional trials.