Purpose: To evaluate the outcome of a web-based digital assessment of visual acuity and refractive error, compared to a manifest refraction assessment, in keratoconus patients with complex refractive errors. Material and methods: Keratoconus patients, aged 18 to 40, with a refractive error between -6 and +4 diopters were eligible. Each participant subsequently underwent a uncorrected visual acuity and a refractive assessment. Refractive error was assessed with the web based tool (index test), autorefractor, and a manifest refraction (reference test) by an optometrist. Corrected visual acuity was assessed with the web based and manifest refractive prescription. Noninferiority was defined as the 95% limits of agreement (95%LoA) of the differences in spherical equivalent between the index and reference test not exceeding plus/minus 0.5 diopters. Agreement was assessed by an intraclass correlation coefficient and Bland Altman analyses. Results: A total of 100 eyes of 50 patients were examined. The overall mean difference of the uncorrected visual acuity measured minus0.01 LogMAR (95%LoA: minus 0.63 to 0.60). The variability decreased in the high uncorrected visual acuity subgroup (mean difference: 0.15 LogMAR, 95%LoA: minus 0.25 to 0.55). The intraclass correlation coefficient of the three refractive assessments was 0.32. The overall mean difference in spherical equivalent between the index and reference test measured minus 0.58 diopters (95%LoA: minus 4.49 to 3.33, P=0.008). The mean differences for myopic and hyperopic subjects were 0.09 diopters (P=0.675) and minus 2.06 diopters (P<0.001), respectively. Conclusions: Our results show promising results in the ability of the web based tool to remotely assess visual acuity in keratoconus patients. The agreement is better in higher visual acuity ranges and could provide physicians with an objective measurement to enhance teleconsultations, especially relevant when access to health care is limited. The assessment of the refractive error using the web based tool was found to be inferior to the manifest refraction and deserves further training of the tools algorithm.

中文翻译：

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基于Web的工具测量圆锥角膜未矫正的视力和屈光不正的评估：前瞻性开放标签方法比较研究

目的：与明显的屈光评估相比，评估具有复杂屈光不正的圆锥角膜患者基于网络的视力和屈光不正数字评估的结果。材料和方法：屈光度在-6至+4屈光度之间的18至40岁的圆锥角膜患者是合格的。每个参与者随后接受未矫正的视敏度和屈光评估。用基于网络的工具（指数测试），自动验光仪和验光师的明显折射（参考测试）评估屈光不正。矫正视力用基于网的和明显的屈光度处方进行评估。非劣效性被定义为指标和参考测试之间球形等效差异不超过正负0.5屈光度的95％一致极限（95％LoA）。通过组内相关系数和布兰德·奥特曼（Bland Altman）分析评估一致性。结果：共检查了50例患者的100眼。未矫正视敏度的总体平均差异为负0.01 LogMAR（95％LoA：负0.63至0.60）。高矫正视敏度亚组的变异性降低（平均差异：0.15 LogMAR，95％LoA：负0.25至0.55）。三种屈光评估的组内相关系数为0.32。指标与参考测试之间的等效球面总平均差为负0.58屈光度（95％LoA：负4.49至3.33，P = 0.008）。近视和远视受试者的平均差异分别为0.09屈光度（P = 0.675）和负2.06屈光度（P <0.001）。结论：我们的结果显示了基于Web的工具能够远程评估圆锥角膜患者视敏度的能力中的有希望的结果。该协议在较高的视敏度范围内更好，并且可以为医师提供客观的测量结果以增强远程会诊，尤其是在无法获得医疗保健的情况下。发现使用基于网络的工具对屈光不正的评估不如明显的屈光，并且值得对工具算法进行进一步的培训。