Miyai Takashi, Miyata Kazunori, Nejima Ryohei, Samejima Tomokazu, Hiraoka Takahiro, Kiuchi Takahiro, Kaji Yuichi, Oshika Tetsuro
Meiwakai Medical Foundation, Miyata Eye Hospital, Miyazaki, Japan.
Ophthalmology. 2005 Mar;112(3):420-4. doi: 10.1016/j.ophtha.2004.09.026.
Fourier harmonic analysis can decompose videokeratography data into spherical power, regular astigmatism, and irregular astigmatism (asymmetry and higher-order irregularity). The aim of this study was to evaluate whether determination of cylinder power by Fourier analysis facilitates measurements of visual acuity and refraction in eyes after penetrating keratoplasty.
Cross-sectional study.
Sixty-six eyes of 56 subjects who had undergone penetrating keratoplasty.
Spectacle-corrected visual acuity was measured in 2 ways: by the conventional and the Fourier methods. In the conventional method, the refraction was determined subjectively by reference to the measurement results of the autokeratometer and autorefractometer. In the Fourier method, the magnitude and axis of regular astigmatism were calculated by Fourier analysis of the videokeratography data, and spherical lenses were adjusted until best spectacle-corrected visual acuity was attained.
Logarithm of the minimum angle of resolution (logMAR) visual acuity and refraction used for correction.
The spectacle-corrected visual acuity obtained with the Fourier method (logMAR, 0.23+/-0.32; Snellen equivalent, 20/34) was significantly better than that attained with the conventional method (logMAR, 0.31+/-0.29; Snellen equivalent, 20/41; P<0.001, paired t test). The cylinder power used for spectacle-corrected visual acuity measurements was significantly lower with the Fourier method (-2.41+/-1.26 diopters [D]) than with the conventional method (-3.53+/-1.64 D; P<0.001). The spherical equivalent at the final refraction was not different between groups (P = 0.207).
Fourier analysis of videokeratography data significantly facilitates determination of refraction and measurement of best spectacle-corrected visual acuity in eyes with corneal irregular astigmatism, such as eyes that have undergone penetrating keratoplasty.
傅里叶谐波分析可将角膜地形图数据分解为球镜度、规则散光和不规则散光（不对称性及高阶不规则性）。本研究的目的是评估通过傅里叶分析确定柱镜度是否有助于测量穿透性角膜移植术后眼睛的视力和屈光情况。
横断面研究。
56例接受穿透性角膜移植术患者的66只眼。
采用两种方法测量眼镜矫正视力：传统方法和傅里叶方法。传统方法中，根据自动角膜曲率计和自动验光仪的测量结果主观确定屈光不正。在傅里叶方法中，通过对角膜地形图数据进行傅里叶分析计算规则散光的度数和轴向，并调整球镜直至获得最佳眼镜矫正视力。
最小分辨角对数（logMAR）视力和用于矫正的屈光不正。
傅里叶方法获得的眼镜矫正视力（logMAR，0.23±0.32；Snellen等效值，20/34）显著优于传统方法（logMAR，0.31±0.29；Snellen等效值，20/41；P<0.001，配对t检验）。傅里叶方法用于眼镜矫正视力测量的柱镜度（-2.41±1.26屈光度[D]）显著低于传统方法（-3.53±1.64 D；P<0.001）。两组最终屈光不正时的等效球镜度无差异（P = 0.207）。
对角膜地形图数据进行傅里叶分析可显著有助于确定角膜不规则散光眼（如穿透性角膜移植术后的眼睛）的屈光不正并测量最佳眼镜矫正视力。
