Ophthalmic Research Group, Aston University, Life and Health Sciences, Birmingham, United Kingdom.
Cornea. 2012 Aug;31(8):849-54. doi: 10.1097/ICO.0b013e318243e42d.
To perform advanced analysis of the corneal deformation response to air pressure in keratoconics compared with age- and sex-matched controls.
The ocular response analyzer was used to measure the air pressure-corneal deformation relationship of 37 patients with keratoconus and 37 age (mean 36 ± 10 years)- and sex-matched controls with healthy corneas. Four repeat air pressure-corneal deformation profiles were averaged, and 42 separate parameters relating to each element of the profiles were extracted. Corneal topography and pachymetry were performed with the Orbscan II. The severity of the keratoconus was graded based on a single metric derived from anterior corneal curvatures, difference in astigmatism in each meridian, anterior best-fit sphere, and posterior best-fit sphere.
Most of the biomechanical characteristics of keratoconic eyes were significantly different from normal eyes (P < 0.001), especially during the initial corneal applanation. With increasing keratoconus severity, the cornea was thinner (r = -0.407, P < 0.001), the speed of corneal concave deformation past applanation was quicker (dive; r2 = -0.314, P = 0.01), and the tear film index was lower (r = -0.319, P = 0.01). The variance in keratoconus severity could be accounted for by the corneal curvature and central corneal thickness (r = 0.80) with biomechanical characteristics contributing an additional 4% (total r = 0.84). The area under the receiver operating characteristic curve was 0.919 ± 0.025 for keratometry alone, 0.965 ± 0.014 with the addition of pachymetry, and 0.972 ± 0.012 combined with ocular response analyzer biomechanical parameters.
Characteristics of the air pressure-corneal deformation profile are more affected by keratoconus than the traditionally extracted corneal hysteresis and corneal resistance factors. These biomechanical metrics slightly improved the detection and severity prediction of keratoconus above traditional keratometric and pachymetric assessment of corneal shape.
与年龄和性别匹配的对照相比，对圆锥角膜的角膜变形对空气压力的反应进行高级分析。
使用眼反应分析仪测量 37 例圆锥角膜患者和 37 例年龄（平均 36 ± 10 岁）和性别匹配的健康角膜对照者的眼压-角膜变形关系。对 4 次重复眼压-角膜变形曲线进行平均，提取与各曲线元素相关的 42 个单独参数。使用 Orbscan II 进行角膜地形图和角膜测厚。根据来源于前角膜曲率、各子午线散光差异、前最佳拟合球体和后最佳拟合球体的单一度量标准，对圆锥角膜的严重程度进行分级。
圆锥角膜眼的大多数生物力学特征与正常眼明显不同（P < 0.001），尤其是在初始角膜压平期间。随着圆锥角膜严重程度的增加，角膜变薄（r = -0.407，P < 0.001），角膜凹陷变形超过压平时的速度更快（潜水；r2 = -0.314，P = 0.01），泪膜指数更低（r = -0.319，P = 0.01）。角膜曲率和中央角膜厚度可以解释圆锥角膜严重程度的差异（r = 0.80），生物力学特征的差异增加了 4%（总 r = 0.84）。单独使用角膜曲率时，受试者工作特征曲线下面积为 0.919 ± 0.025，增加角膜测厚时为 0.965 ± 0.014，联合使用眼反应分析仪生物力学参数时为 0.972 ± 0.012。
与传统提取的角膜滞后和角膜阻力因子相比，眼压-角膜变形曲线的特征受圆锥角膜的影响更大。这些生物力学指标在传统的角膜形态学评估（包括角膜曲率和角膜测厚）之上，对圆锥角膜的检测和严重程度预测略有改善。
