Differentiation of mild keratoconus from corneal warpage according to topographic inferior steepening based on corneal tomography data

ABSTRACT We report two cases of suspicious asymmetric bow tie and inferior steepening on topographic evaluations with reflection (Placido) and projection (Scheimpflug). Rotating Scheimpflug corneal and anterior segment tomography (Oculus Pentacam HR, Wetzlar, Germany)® was performed in the first case, with a maximal keratometric value (Kmax) of 43.2 D and an overall deviation value from the Belin/Ambrósio Enhanced Ectasia Display (BAD-D) of 1.76, which was observed in the study eye (OD). BAD-D was 6.59 in the fellow eye, which had clinical findings that were consistent with keratoconus stage 2. The second case presented with a Kmax of 45.3 D and BAD-D of 0.76 in OD and 1.01 in OS. This patient had discontinued wearing soft contact lens less than 1 day prior to examination. Corneal tomographic data enabled us to distinguish mild or forme fruste keratoconus from contact lens-induced corneal warpage, and similar findings were observed on curvature maps.摘要：本研究报告2例经反射式（普拉西多（Placido））与投射式Scheimpflug地形图评估，发现可疑不对称蝶形征及下方角膜变陡的病例。首例患者接受旋转式Scheimpflug角膜及眼前节断层扫描（德国韦茨拉尔Oculus Pentacam HR®）检查，患眼（右眼，OD）的最大角膜曲率值（Kmax）为43.2 D，贝林/安布罗西奥增强圆锥角膜异常显示系统（BAD-D）整体偏离值为1.76；对侧眼的BAD-D值为6.59，其临床体征符合2期圆锥角膜诊断标准。第二例患者右眼（OD）的Kmax为45.3 D，BAD-D值为0.76，左眼（OS）BAD-D值为1.01，该患者于检查前不足1天停止佩戴软性角膜接触镜。角膜断层扫描数据可辅助鉴别轻度圆锥角膜/顿挫型圆锥角膜与软性角膜接触镜诱发的角膜曲率变形，曲率地形图亦可见类似异常表现。