J Refract Surg. 2022 May;38(5):318-325. doi: 10.3928/1081597X-20220225-01. Epub 2022 May 1.
To determine the effectiveness of parameters and indices based on biomechanical measures at discriminating fellow eyes with topographically and tomographically normal corneas in patients with keratoconus from normal control corneas.
The study included 47 keratoconus suspect eyes, defined as the topographically and tomographically normal fellow eyes of patients with frank keratoconus in the other eye. Eyes were imaged using the Pentacam HR and Corvis ST (both Oculus Optikgeräte GmbH). Fellow eyes were then categorized as topographically/tomographically normal fellow eyes (TNF) and topographically/tomographically borderline fellow eyes (TBF). The ability of each of the Corvis Biomechanical Index (CBI), Tomographic and Biomechanical Index (TBI), stiffness parameter at applanation 1 (SP-A1), and stress-strain index (SSI) at discriminating between normal controls and keratoconus suspects was assessed.
The TBI had the best discriminative ability with the greatest area under the receiver operating characteristic (AUROC) curve value of 0.946 for normal controls versus TBF eyes, and 0.824 for normal controls versus TNF eyes. Compared to the TBI AUROC curves, SP-A1 and CBI had AUROC curve values of 0.833 ( = .09) and 0.822 ( = .01) for normal controls versus TBF eyes, respectively, and AUROC curve values of 0.822 ( = .96) and 0.550 ( = .0002) for normal controls versus TNF eyes, respectively. The TBI had the best positive predictive value for TNF and TBF eyes, followed by CBI and SP-A1.
The TBI and the purely biomechanical parameter SP-A1 were of moderate utility in distinguishing between normal and keratoconus suspect eyes. In the absence of topographic/tomographic evidence of keratectasia, an independently abnormal biomechanical parameter may suggest an increased risk of ectasia. .
确定基于生物力学测量的参数和指标在区分伴有明显角膜地形和角膜断层异常的圆锥角膜患者的正常对侧眼与正常对照眼角膜方面的有效性。
该研究纳入了 47 只圆锥角膜可疑眼,定义为对侧眼为明确圆锥角膜的患者的正常角膜地形和角膜断层正常的对侧眼。使用 Pentacam HR 和 Corvis ST(均为 Oculus Optikgeräte GmbH)对眼进行成像。然后将对侧眼分为正常角膜地形/断层正常对侧眼(TNF)和正常角膜地形/断层交界对侧眼(TBF)。评估了 Corvis 生物力学指数(CBI)、断层和生物力学指数(TBI)、压平 1 处的刚性参数(SP-A1)和应力-应变指数(SSI)各自在区分正常对照眼与圆锥角膜可疑眼方面的能力。
TBI 具有最佳的鉴别能力,其在正常对照眼与 TBF 眼之间的受试者工作特征(ROC)曲线下面积(AUROC)值最大,为 0.946,在正常对照眼与 TNF 眼之间为 0.824。与 TBI AUROC 曲线相比,SP-A1 和 CBI 在正常对照眼与 TBF 眼之间的 AUROC 曲线值分别为 0.833(=0.09)和 0.822(=0.01),在正常对照眼与 TNF 眼之间的 AUROC 曲线值分别为 0.822(=0.96)和 0.550(=0.0002)。TBI 对 TNF 和 TBF 眼具有最佳的阳性预测值,其次是 CBI 和 SP-A1。
TBI 和纯粹的生物力学参数 SP-A1 对于区分正常眼和圆锥角膜可疑眼具有中等效用。在没有角膜地形/角膜断层扩张证据的情况下,独立的异常生物力学参数可能提示扩张的风险增加。