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- Title
Repeatability of mesopic visual acuity measurements using high- and low-contrast ETDRS letter charts.
- Authors
Barrio, Ana; Antona, Beatriz; Puell, María
- Abstract
Purpose: To determine the repeatability of mesopic high-contrast (HC) and low-contrast (LC) visual acuity (VA) measurements made at distance and near in healthy young individuals. While the repeatability of photopic VA is well-known, there is a lack of information with regard to the repeatability of VA measured under low luminance conditions. Methods: In two different sessions 1 week apart, best-corrected monocular VA was determined using HC (96 %) and LC (10 %) ETDRS charts under mesopic luminance conditions (0.75 cd/m) at distance (HCD, LCD) and near (HCN, LCN) in 47 healthy subjects aged 22.9 ± 6.8 years. Repeatability was estimated by the Bland and Altman method, whereby the mean difference (MD) and the 95 % limits of agreement were determined as the coefficient of repeatability (COR). Results: Mean logMAR VA values were HCD = 0.09, LCD = 0.44, HCN = 0.21, and LCN = 0.57. Mean differences in measurements between sessions 1 and 2 were not significant, and low in clinical terms (≤1 letter). Repeatability was better for the distance measurements at both high and lowcontrast (COR ±0.11 and COR ±0.11 logMAR vs COR ±0.15 and COR ±0.16 logMAR), and MDs were also slightly closer to zero for the distance measurements. Similar repeatability was observed between HC and LC VA, both at distance and near. Conclusions: In mesopic conditions, ETDRS charts offer repeatable best-corrected monocular VA measurements. The criterion for a significant change in logMAR VA was 1 line at distance and 1.5 lines at near.
- Subjects
DIABETIC retinopathy treatment; VISUAL acuity; DIABETIC retinopathy; MONOCULAR vision; DIAGNOSIS; PATIENTS
- Publication
Graefe's Archive of Clinical & Experimental Ophthalmology, 2015, Vol 253, Issue 5, p791
- ISSN
0721-832X
- Publication type
Article
- DOI
10.1007/s00417-014-2876-z