Szczotka L B, Rabinowitz Y S, Yang H
Department of Ophthalmology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA.
CLAO J. 1996 Oct;22(4):270-3.
Corneal videokeratography is frequently used to evaluate keratoconus patients, as it is believed to allow for a more thorough appreciation of the complex curvature changes associated with the anterior corneal surface. The goal of this study was to determine the qualitative and quantitative influence of soft and rigid contact lens wear on the corneal topography of keratoconus.
205 keratoconus patients were analyzed by computerized videokeratography for both qualitative corneal topographic patterns and quantitative indices. Fifty-six patients were non-contact lens wearers, 130 wore polymethylmethacrylate (PMMA) or rigid gas permeable (RGP) contact lenses, and 19 wore soft contact lenses. Data from the keratoconus patients were also compared to a control group comprised of normal patients with no history of contact lens wear.
All three keratoconus groups had a significantly increased frequency of an asymmetric bowtie/skewed radial axes (AB/SRAX) pattern compared with normals. Differences among the videokeratography patterns for the kertoconus patients included a significant shift from the AB/SRAX videokeratographic pattern to the irregular videokeratographic pattern in the rigid (PMMA or RGP) lens subgroup as well as an increased frequency of the irregular pattern in the soft contact lens group versus the no contact lens group (P < 0.0001). Additional differences between the rigid contact lens and no contact lens keratoconus groups included increased values for the quantitative indices of SAI, SRI, SIM-K, and central K in the rigid contact lens group (P < 0.05).
The increased frequency of qualitative and quantitative corneal irregularity in the rigid contact lens keratoconus group may reflect a mechanical effect of contact lens wear or an advanced disease state in these patients limiting them to rigid lens wear. The advanced disease is evidenced by steeper SIM-K and Central K indices in the rigid contact lens group.
角膜视频角膜地形图常用于评估圆锥角膜患者，因为人们认为它能更全面地了解与角膜前表面相关的复杂曲率变化。本研究的目的是确定软性和硬性隐形眼镜佩戴对圆锥角膜患者角膜地形图的定性和定量影响。
通过计算机化视频角膜地形图分析205例圆锥角膜患者的角膜地形图定性模式和定量指标。56例患者不佩戴隐形眼镜，130例佩戴聚甲基丙烯酸甲酯（PMMA）或硬性透气性（RGP）隐形眼镜，19例佩戴软性隐形眼镜。圆锥角膜患者的数据也与一个由无隐形眼镜佩戴史的正常患者组成的对照组进行了比较。
与正常人相比，所有三个圆锥角膜组的不对称领结/倾斜径向轴（AB/SRAX）模式频率均显著增加。圆锥角膜患者的视频角膜地形图模式之间的差异包括，在硬性（PMMA或RGP）镜片亚组中，从AB/SRAX视频角膜地形图模式显著转变为不规则视频角膜地形图模式，以及软性隐形眼镜组与无隐形眼镜组相比，不规则模式的频率增加（P < 0.0001）。硬性隐形眼镜组和无隐形眼镜的圆锥角膜组之间的其他差异包括，硬性隐形眼镜组中SAI、SRI、SIM-K和中央K的定量指标值增加（P < 0.05）。
硬性隐形眼镜圆锥角膜组中角膜定性和定量不规则性频率的增加，可能反映了隐形眼镜佩戴的机械效应，或这些患者的疾病进展状态使他们只能佩戴硬性镜片。硬性隐形眼镜组中更陡峭的SIM-K和中央K指标证明了疾病进展。
