Kojima Takashi, Isogai Naoki, Nishida Tomoya, Nakamura Tomoaki, Ichikawa Kazuo
Department of Ophthalmology, Keio University School of Medicine, Shinanomachi 35, Shinjuku-ku, Tokyo 160-8582, Japan.
Nagoya Eye Clinic, Nagoya 456-0003, Japan.
Diagnostics (Basel). 2021 Nov 15;11(11):2120. doi: 10.3390/diagnostics11112120.
The keratometer keratoconus index (KKI) is a diagnostic index for the risk of keratoconus calculated from autokeratometer test values. We partially modified the KKI equation and assessed it without limiting the target age and severity of keratoconus. This retrospective study included 179 eyes of 99 patients with keratoconus and 468 eyes from 235 normal controls. In the modified KKI, oblique astigmatism or against-the-rule astigmatism was defined as ≥1D astigmatism. KKI diagnostic power was analyzed in subgroups of <50 and ≥50-year-old patients, and at different keratoconus stages. Although the sensitivity of modified KKI was comparable with that of original KKI (92.7% vs. 95.5%), modified KKI specificity was significantly higher (79.7% vs. 68.6%) ( = 0.0001). Using the modified KKI, sensitivity reached 100% (4/4) and specificity, 63.5% (33/52), in ≥50-year-old patients, while overall sensitivity in keratoconus ≥stage 2 was 100% (30/30). In conclusion, the modified KKI proved to be effective in keratoconus screening at all stages. However, it should be noted that false-positive frequency is higher in ≥50-year-old patients.
角膜曲率计圆锥角膜指数（KKI）是一种根据自动角膜曲率计测试值计算得出的圆锥角膜风险诊断指数。我们对KKI方程进行了部分修改，并在不限制圆锥角膜目标年龄和严重程度的情况下对其进行了评估。这项回顾性研究纳入了99例圆锥角膜患者的179只眼以及235名正常对照者的468只眼。在修改后的KKI中，斜轴散光或逆规散光被定义为散光≥1D。在年龄<50岁和≥50岁的患者亚组以及不同圆锥角膜阶段分析了KKI的诊断效能。尽管修改后的KKI敏感性与原始KKI相当（92.7%对95.5%），但修改后的KKI特异性显著更高（79.7%对68.6%）（P = 0.0001）。使用修改后的KKI，≥50岁患者的敏感性达到100%（4/4），特异性为63.5%（33/52），而在圆锥角膜≥2期患者中的总体敏感性为100%（30/30）。总之，修改后的KKI在圆锥角膜各阶段筛查中均被证明是有效的。然而，需要注意的是，≥50岁患者的假阳性频率更高。
