Illinois College of Optometry, Chicago, Illinois.
Salus University Pennsylvania College of Optometry, Elkins Park, Pennsylvania.
Optom Vis Sci. 2020 May;97(5):370-376. doi: 10.1097/OPX.0000000000001506.
Automated low-contrast letter acuity (LCLA) has several advantages: consistent luminance, reduced chance of individuals memorizing test letters, and convenient and accurate visual acuity reporting functions. Although automated LCLA might report slightly worse acuity than Sloan LCLA chart, considering its advantages, it may be a viable alternative to Sloan LCLA chart in clinical practice and research.
The purpose of this study was to determine the repeatability of an automated LCLA measurement and its agreement with the Sloan LCLA chart test in normal participants and reduced-vision participants.
Adult participants (n = 49) were measured with both automated Early Treatment Diabetic Retinopathy Study and Sloan LCLA tests, including normal and reduced-vision groups. Low-contrast letter acuity at two contrast levels (2.5 and 10%) was measured at 3 m in a random sequence with both LCLA tests. To test repeatability, participants were retested 1 week later. Repeatability of the two tests between two visits and agreement between automated and Sloan LCLA tests were evaluated using 95% limits of agreement.
In terms of the 95% limits of agreement, the repeatability of both tests was as follows: automated LCLA at 2.5%, ±0.26; automated LCLA at 10%, ±0.22; Sloan LCLA at 2.5%, ±0.23, and Sloan LCLA at 10%, ±0.16. The agreement of the two tests was as follows: ±0.19 at 2.5% and ±0.24 at 10%. The automated LCLA at 2.5 and 10% levels was generally reported one-half to one logMAR line lower than Sloan LCLA (mean differences, -0.04 at 2.5% and -0.13 at 10%; paired t test, P < .05).
The automated LCLA test shows fairly good test-retest repeatability at both 2.5 and 10% contrast levels. The agreement between the automated and the Sloan low-contrast letter acuity tests was comparable with test-retest agreement. Although the automated LCLA test reports slightly worse acuity than the Sloan LCLA test, it could be an appropriate alternative to the Sloan LCLA test.
自动化低对比度字母视力（LCLA）具有几个优点：一致的亮度、减少个人记忆测试字母的机会，以及方便和准确的视力报告功能。虽然自动化 LCLA 可能报告的视力比 Sloan LCLA 图表稍差，但考虑到其优点，它可能是临床实践和研究中 Sloan LCLA 图表的可行替代方案。
本研究旨在确定自动化 LCLA 测量的重复性及其在正常参与者和低视力参与者中与 Sloan LCLA 图表测试的一致性。
成人参与者（n = 49）使用自动早期糖尿病视网膜病变研究和 Sloan LCLA 测试进行测量，包括正常和低视力组。在 3 米处以随机顺序用两种 LCLA 测试测量两种对比度水平（2.5%和 10%）的低对比度字母视力。为了测试重复性，参与者在一周后进行了重新测试。通过 95%一致性界限评估两次就诊时两种测试的重复性以及自动化和 Sloan LCLA 测试之间的一致性。
在 95%一致性界限方面，两种测试的重复性如下：自动化 LCLA 在 2.5%时，±0.26；自动化 LCLA 在 10%时，±0.22；Sloan LCLA 在 2.5%时，±0.23，以及 Sloan LCLA 在 10%时，±0.16。两种测试的一致性如下：在 2.5%时为±0.19，在 10%时为±0.24。自动化 LCLA 在 2.5%和 10%水平通常比 Sloan LCLA 报告低半到一个 logMAR 线（平均差异，在 2.5%时为-0.04，在 10%时为-0.13；配对 t 检验，P<.05）。
自动化 LCLA 测试在 2.5%和 10%两种对比度水平下均显示出相当好的测试-重测可重复性。自动化和 Sloan 低对比度字母视力测试之间的一致性与测试-重测一致性相当。虽然自动化 LCLA 测试报告的视力比 Sloan LCLA 测试略差，但它可能是 Sloan LCLA 测试的合适替代方案。
