Oshika T, Tomidokoro A, Maruo K, Tokunaga T, Miyata N
Department of Ophthalmology, University of Tokyo School of Medicine, Japan.
Invest Ophthalmol Vis Sci. 1998 Apr;39(5):705-9.
To assess quantitatively corneal irregular astigmatism in association with best spectacle-corrected visual acuity.
Refractive powers on a mire ring measured with computerized videokeratography were decomposed, using the Fourier series harmonic analysis. Extracting spherical and regular astigmatic components, the remaining irregular astigmatic component was quantified on rings 2 through 9. A weighted average was calculated by using the Stiles-Crawford effect on the basis of the radius of each ring of each eye and was used as an index of the irregular astigmatic component. Data analyses were carried out in 108 eyes, including 53 normal eyes, 34 eyes with keratoconus, and 21 eyes that had undergone penetrating keratoplasty for keratoconus. Keratoconic eyes and eyes after keratoplasty were included in the study only if visual acuity, corrected with a hard contact lens, was 20/20 or better. Logarithm of best spectacle-corrected visual acuity, age, type of disease, refractive astigmatism, irregular astigmatic component, surface regularity index, and surface asymmetry index were analyzed.
In results of multiple regression analysis, the irregular astigmatic component was significantly correlated with best spectacle-corrected visual acuity (r = -0.744; adjusted R2 = 0.549; P < 0.001), whereas other explanatory variables showed no correlation with best spectacle-corrected visual acuity.
This model of the irregular astigmatic component seems to be an efficient, quantitative means of describing corneal irregular astigmatism.
定量评估角膜不规则散光与最佳眼镜矫正视力的关系。
使用计算机化视频角膜地形图测量的角膜环上的屈光力，采用傅里叶级数谐波分析进行分解。提取球镜和规则散光成分后，在第2至9环上对剩余的不规则散光成分进行量化。根据每只眼睛各环的半径，利用斯泰尔斯-克劳福德效应计算加权平均值，并将其用作不规则散光成分的指标。对108只眼睛进行了数据分析，其中包括53只正常眼睛、34只圆锥角膜眼睛和21只因圆锥角膜接受穿透性角膜移植术的眼睛。只有在硬性接触镜矫正视力为20/20或更好的情况下，圆锥角膜眼睛和角膜移植术后的眼睛才被纳入研究。分析了最佳眼镜矫正视力的对数、年龄、疾病类型、屈光性散光、不规则散光成分、表面规则性指数和表面不对称指数。
在多元回归分析结果中，不规则散光成分与最佳眼镜矫正视力显著相关（r = -0.744；调整后R2 = 0.549；P < 0.001），而其他解释变量与最佳眼镜矫正视力无相关性。
这种不规则散光成分模型似乎是描述角膜不规则散光的一种有效、定量的方法。
