PURPOSE To determine optimal objective, machine-derived variables and variable combinations from Scheimpflug and spectral-domain (SD) OCT imaging to distinguish the clinically unaffected eye in patients with asymmetric keratoconus (AKC) from a normal control population. DESIGN Retrospective case-control study. PARTICIPANTS Thirty clinically unaffected eyes with no physical findings on slit-lamp examination, no definitive abnormalities on corneal imaging, and corrected distance acuity of 20/20 or better from 30 patients with highly AKC eyes and 60 eyes from 60 normal control patients who had undergone uneventful LASIK with at least 2 years of stable follow-up (controls). METHODS Scheimpflug and SD OCT imaging were obtained in all eyes, and receiver operating characteristic (ROC) curves were generated to determine area under the curve (AUC), sensitivity, and specificity for each machine-derived variable and variable combination. MAIN OUTCOME MEASURES Distinguishing AKC eyes from controls as determined by AUC, sensitivity, and specificity. RESULTS No individual machine-derived metric from Scheimpflug or SD OCT technology yielded an AUC higher than 0.75. Combining 5 Scheimpflug metrics (index height decentration [IHD], index vertical asymmetry [IVA], pachymetry apex, inferior-superior value, and Ambrosio's Relational Thickness Maximum [ARTmax]) yielded the best Scheimpflug results (AUC 0.86, sensitivity 83%, specificity 83%). Combining 11 SD OCT thickness metrics (minimum-median, temporal outer, superior nasal outer, minimum, epithelium minimum-maximum, epithelial standard deviation, superior inner, superior outer, superior temporal outer, superior nasal inner, central) yielded the best SD OCT results (AUC 0.96, sensitivity 89%, specificity 89%). Combining 13 total Scheimpflug/SD OCT metrics yielded the best results overall (AUC 1.0, sensitivity 100%, specificity 100%). The most impactful variables in combined models included epithelial thickness variability and total focal corneal thickness variability from SD OCT and anterior curvature and topometric indices from Scheimpflug technology. No posterior corneal metrics were impactful in modeling. CONCLUSIONS Individual machine-derived metrics from Scheimpflug and SD OCT imaging poorly distinguished normal eyes from minimally affected eyes from patients with highly AKC. Combined SD OCT metrics performed better than combined Scheimpflug metrics. Combining anterior curvature and asymmetry indices from Scheimpflug with regional total thickness and epithelial thickness variability metrics from SD OCT clearly distinguished the 2 populations. Posterior corneal indices were not useful in distinguishing populations.

中文翻译：

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结合使用Scheimpflug和光谱域OCT分析来区分高度不对称的圆锥角膜眼。

目的从Scheimpflug和光谱域（SD）OCT成像确定最佳的客观，机器衍生变量和变量组合，以区分非对称性圆锥角膜（AKC）患者与正常对照人群的临床未受影响的眼睛。设计回顾性病例对照研究。参加者30例临床未受影响的眼睛，裂隙灯检查未见任何物理发现，角膜成像未见明确异常，且30例AKC高眼患者和60例正常对照患者的60眼矫正距离视力为20/20或更好至少2年的稳定随访（对照）的LASIK手术。方法在所有眼睛中均获得Scheimpflug和SD OCT成像，并生成接收器工作特性（ROC）曲线以确定该曲线下的面积（AUC），每个机器衍生的变量和变量组合的敏感性和特异性。主要观察指标根据AUC，敏感性和特异性确定将AKC眼睛与对照区分开。结果没有来自Scheimpflug或SD OCT技术的机器衍生指标，其AUC均高于0.75。结合5种Scheimpflug度量标准（指数高度偏心[IHD]，指数垂直不对称[IVA]，测厚顶点，下优值和Ambrosio的最大关系厚度[ARTmax]）产生了最佳的Scheimpflug结果（AUC 0.86，灵敏度83％，特异性83％）。结合11种SD OCT厚度量度（最低中位，颞外，鼻上外，最小，上皮最小-最大值，上皮标准偏差，上内，上外，上颞外，上鼻内，中央）产生最好的SD OCT结果（AUC 0.96，敏感性89％，特异性89％）。总的来说，将13种Scheimpflug / SD OCT指标结合起来可得出最佳结果（AUC 1.0，灵敏度100％，特异性100％）。组合模型中影响最大的变量包括SD OCT的上皮厚度变异性和总局灶性角膜厚度变异性以及Scheimpflug技术的前曲率和形貌指数。没有后角膜指标对建模有影响。结论来自Scheimpflug和SD OCT成像的机器衍生指标很难区分正常眼睛和高度AKC患者的影响最小的眼睛。SD OCT组合指标的性能优于Scheimpflug组合指标。将Scheimpflug的前曲率和不对称指数与SD OCT的区域总厚度和上皮厚度变异性指标结合起来可以清楚地区分这两个人群。后角膜指数在区分人群中没有用。