Abstract
Purpose :
In clinical trials, best-corrected visual acuity (BCVA) of non-English speaking individuals sometimes is measured with the ETDRS Landolt C chart, which may not reflect true BCVA in those with left-right confusion. Reliability of a commercial ETDRS numeric chart has not yet proven. This cross-sectional study evaluates repeatability and concordance of ETDRS number charts with the ETDRS Landolt C and ETDRS alphabet charts in normal eyes and eyes with sight-threatening conditions.
Methods :
Following IRB approval, Thai participants who can speak English were recruited as group A: 60 participants with normal vision (BCVA 20/20-20/25); group B: 40 participants with BCVA 20/20-20/40 due to senile cataract (SC), diabetic macular edema (DME), or age-related macular degeneration (AMD); group C: 40 participants with BCVA 20/50-20/100 due to SC, DME, or AMD; and, group D: 14 participants with BCVA 20/125-20/200 due to SC, DME, or AMD. Each participant underwent standardized BCVA measurements at 4 meters with three types of ETDRS charts (Precision-Vision®, Woodstock, IL) including PV numbered, Landolt C, and original alphabet charts in a random sequence, twice, with at least 30 minutes apart. Mean BCVA were analyzed for repeatability and concordance using Pearson’s correlation coefficient and intra-class correlation, respectively.
Results :
Of 154 participants (47% men, 154 study eyes), mean age was 52.9 (±18.2) years. Repeatability coefficients of the ETDRS number chart were 0.61 in group A (95% confidence interval [CI]: 0.42-0.75), 0.87 in group B (95% CI: 0.78-0.93), 0.81 in group C (95% CI: 0.67-0.90), and 0.81 in group D (95% CI: 0.49-0.94). Concordance correlation coefficients (CCC) between number and Landolt C charts were 0.61 (95% CI: 0.35-0.77) in group A, 0.83 (95% CI: 0.68-0.91) in group B, 0.77 (0.56-0.88) in group C, and 0.75 (0.22-0.92) in group D. CCC between number and original alphabet charts were 0.89 (0.82-0.93) in group A, 0.97 (0.94-0.98) in group B, 0.92 (0.86-0.96) in group C, and 0.96 (0.87-0.99) in group D.
Conclusions :
These data suggest the ETDRS number chart can be used in non-English speaking individuals with normal vision or sight-threatening conditions with high repeatability, and high concordance with Landolt C and alphabet charts.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.