Zhang Lu, Zhang Yue, Liu Yanlin, Wang Kai, Zhao Mingwei
Department of Ophthalmology & Clinical Centre of Optometry, Peking University People's Hospital, Beijing, 100044, China; College of Optometry, Peking University Health Science Centre, Beijing, 100044, China; Beijing Key Laboratory for the Diagnosis and Treatment of Retinal and Choroid Diseases, Beijing, 100044, China.
General Hospital of Air Force, Beijing, 100142, China.
Cont Lens Anterior Eye. 2017 Dec;40(6):401-407. doi: 10.1016/j.clae.2017.09.018. Epub 2017 Oct 4.
To evaluate a novel fitting algorithm for estimation of alignment curve (AC) radius during orthokeratology lens trial.
Fifty myopic children were recruited in this study. AC radii were estimated by both traditional method using flat K readings and eccentricity values and by a novel fitting algorithm, which was composed of 256 circle fittings using corneal elevation data from the corresponding AC region and a succedent toric fitting based on these calculated AC curvatures. Parameters of the final ordered lenses were determined by fluorescein analysis and corneal topography. The number of lens trials was recorded for each patient, and the consistencies of AC radius and astigmatism between the first trial lenses and the final ordered lenses were tested by Pearson correlations and Bland-Altman plots.
The numbers of trials for the novel algorithm and traditional method were 1.2±0.4 times vs. 1.8±0.7 times, respectively, and Mann-Whitney test showed significant difference (z=-3.27, p=0.001). AC radii of the first trial lenses estimated by the novel fitting algorithm were more close to that of the final ordered lenses, showing a R square value of 0.994 for the fitting algorithm and 0.927 for the traditional method, respectively. Similar results could also be noticed for astigmatism estimation.
AC radius and astigmatism of ortho-k lens could be better estimated by two steps of fitting algorithm using corneal elevation data, which may shorten the time needed for ortho-k lens trial and achieve better lens fitting status.
评估一种用于在角膜塑形镜试戴期间估计配适曲线（AC）半径的新型拟合算法。
本研究招募了50名近视儿童。通过使用平坦角膜曲率读数和偏心率值的传统方法以及一种新型拟合算法来估计AC半径，该新型拟合算法由使用来自相应AC区域的角膜高度数据的256次圆拟合以及基于这些计算出的AC曲率的后续复曲面拟合组成。最终订购镜片的参数通过荧光素分析和角膜地形图确定。记录每位患者的镜片试戴次数，并通过Pearson相关性和Bland - Altman图测试首次试戴镜片与最终订购镜片之间AC半径和散光的一致性。
新型算法和传统方法的试戴次数分别为1.2±0.4次和1.8±0.7次，Mann - Whitney检验显示有显著差异（z = -3.27，p = 0.001）。通过新型拟合算法估计的首次试戴镜片的AC半径更接近最终订购镜片的AC半径，拟合算法的R平方值分别为0.994，传统方法为0.927。散光估计也有类似结果。
使用角膜高度数据的两步拟合算法可以更好地估计角膜塑形镜的AC半径和散光，这可能会缩短角膜塑形镜试戴所需时间并实现更好的镜片配适状态。
