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

Abstract

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. 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. 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). 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.