Abstract
Abstract: :
Purpose:Stargardt disease/fundus flavimaculatus (STGD/FF) (OMIM 248200) is an autosomal recessive juvenile macular dystrophy, which leads to a decline in central vision. Due to reduced visual acuity associated with a central scotoma, patients with STGD frequently complain of difficulties reading. The purpose of this study was to quantify reading speed in patients with central scotomas due to Stargardt disease. Methods:To date, 24 patients with Stargardt disease and 15 control subjects have been included in this study. The patients (17 women, 7 men, with ages ranging between 15 and 63 years) underwent a full ophthalmological and visual function evaluation and were screened for ABCR gene mutations. The control subjects (12 women, 3 men, with ages ranging between 14 and 47 years) all had a corrected visual acuity of 20/20 or better. Reading speed was measured binocularly using MNread acuity charts (G Legge et al, 1989). Both charts ∼ black letters on white background (b/w) and white letters on black background (w/b) ∼ were used. Statistical analysis was performed using analysis of variance and correlation methods. Results:Study variables were maximal reading speed (MRS), reading visual acuity (RVA), and critical print size (CPS), the smallest print size readable at maximum speed. As expected, MRS was significantly slower in patients vs. controls (119 ± 46 vs. 165 ± 33 words per minute) (mean ± sd). RVA was significantly worse in patients vs. controls (0.73 ± 0.25 vs. –0.15 ± 0.01 logMAR). Similarly, CPS was significantly larger in patients vs. controls (1.08 ± 0.24 vs. 0.09 ± 0.11 logMAR). No significant differences were seen between results with b/w and w/b charts. There was a strong association between best–corrected acuity (BCVA), RVA, and CPS. In contrast, the association between BCVA and MRS was weak. Conclusions:Reading speed measurements provided a valuable addition for the assessment of visual function in STGD/FF. Patients with large central scotomas (typical FF) performed worse than those with smaller ones (typical STGD). MRS could not be accurately predicted by BCVA, suggesting that it is an independent estimator of visual function. Knowledge of the CPS may be useful to select the appropriate magnification required by a given patient. MNread charts provided a simple approach for office measurements of reading speed.
Keywords: reading • retinal degenerations: hereditary • low vision