Retina Consultants of Houston, Retina Consultants of America, Houston, Texas.
Vitreoretinal Service, Cole Eye Institute, Cleveland Clinic, Cleveland, Ohio.
Ophthalmol Retina. 2021 Mar;5(3):224-233. doi: 10.1016/j.oret.2020.04.011. Epub 2020 Apr 23.
To compare the variability between Snellen visual acuity (VA) and Early Treatment Diabetic Retinopathy (ETDRS) best-corrected VA (BCVA) measurements.
Retrospective chart review.
Eyes from subjects entering 12 prospective retinal trials in a large, urban retina practice.
Eyes were included if a Snellen VA measurement was performed at the visit preceding trial screening and VA was better than counting fingers. Snellen VA and ETDRS BCVA were then converted to logarithm of the minimum angle of resolution (logMAR) units, and the variability between measurements was calculated.
Outcome measures include VA variability among disease states, absolute VA, and central subfield thickness (CST).
A total of 773 eyes of 413 subjects were identified with a mean of 27.2 days (median, 19; 95% confidence interval [CI], 25.1-29.3) between measurements. Mean Snellen and ETDRS measurements were 0.40 (20/50) and 0.27 logMAR (20/40), respectively. Overall, mean ETDRS BCVA was 6.1 letters better than Snellen VA (median, 5.8; 95% CI, 5.3-7.0; P < 0.05); 76.6% of eyes had improved ETDRS. Restricting the number of days between measurements did not result in any meaningful differences from this directionality. Among eyes with worse VA, variation was more pronounced than among eyes with better VA; eyes 20/25 or better were a mean +1.9 letters better on ETDRS testing (P < 0.05) and eyes 20/160 or worse were a mean +12.6 letters better on ETDRS testing (P < 0.05). Subgroup analyses by disease state found statistically significantly better vision measurements with the ETDRS protocol compared with Snellen in 4 of the 5 disease states studied. Although lens status did not affect the extent of discrepancy between ETDRS and Snellen measurements, amount of retinal edema (CST) did: increased CST correlated with increased variability.
The ETDRS protocol BCVA measurement resulted in significantly better scores when compared with Snellen VA measurements. This difference was more pronounced among eyes with worse VA. Additionally, specific retinal disease states and anatomic variables such as extent of retinal edema (CST) may have a meaningful impact on the anticipated variability between ETDRS and Snellen VA measurement.
比较 Snellen 视力（VA）和早期糖尿病视网膜病变治疗研究（ETDRS）最佳矫正视力（BCVA）测量之间的变异性。
回顾性图表审查。
来自大型城市视网膜实践中参加 12 项前瞻性视网膜试验的受试者的眼睛。
如果在试验筛选前的就诊时进行了 Snellen VA 测量，并且 VA 优于数手指，则将眼睛纳入研究。然后将 Snellen VA 和 ETDRS BCVA 转换为最小角分辨率的对数（logMAR）单位，并计算测量之间的变异性。
观察指标包括疾病状态之间的 VA 变异性、绝对 VA 和中央视网膜厚度（CST）。
共确定了 773 只眼睛的 413 名受试者，两次测量之间的平均时间为 27.2 天（中位数为 19；95%置信区间[CI]，25.1-29.3）。Snellen 和 ETDRS 的平均测量值分别为 0.40（20/50）和 0.27 logMAR（20/40）。总体而言，ETDRS BCVA 平均比 Snellen VA 好 6.1 个字母（中位数，5.8；95%CI，5.3-7.0；P<0.05）；76.6%的眼睛 ETDRS 改善。限制两次测量之间的天数并没有导致这种方向性的任何有意义的差异。在 VA 较差的眼睛中，变异性比 VA 较好的眼睛更明显；VA 为 20/25 或更好的眼睛在 ETDRS 测试中平均提高了 1.9 个字母（P<0.05），VA 为 20/160 或更差的眼睛在 ETDRS 测试中平均提高了 12.6 个字母（P<0.05）。按疾病状态进行的亚组分析发现，在研究的 5 种疾病状态中，有 4 种状态的 ETDRS 方案与 Snellen 相比，视力测量结果明显更好。尽管晶状体状态并不影响 ETDRS 和 Snellen 测量之间差异的程度，但视网膜水肿（CST）的程度确实有影响：CST 增加与变异性增加相关。
与 Snellen VA 测量相比，ETDRS 方案 BCVA 测量结果明显更好。在 VA 较差的眼睛中，这种差异更为明显。此外，特定的视网膜疾病状态和解剖学变量，如视网膜水肿（CST）的程度，可能对 ETDRS 和 Snellen VA 测量之间的预期变异性有重要影响。
