光学治疗区偏心对角膜塑形镜配戴后角膜高阶像差及眼轴发育的影响

Influence of Treatment Zone Decentration on Corneal Higher-order Wavefront Aberrations and Axial Length ELongation after Orthokeratology

目的：研究角膜塑形镜戴镜后光学治疗区偏心状态对近视儿童角膜高阶像差及眼轴发育的影响。方法：前瞻性临床研究。选取8．14岁接受角膜塑形术的近视儿童20例（40眼），测量戴镜前，戴镜后1周、6个月及1．5年角膜地形图、角膜高阶像差和眼轴。比较角膜塑形镜戴镜后光学治疗区不同偏心状态各时间点角膜高阶像差的变化，分析戴镜后光学治疗区偏心状态与眼轴变化值的相关性。采用重复测量方差分析、Pearson相关性分析和配对t检验进行数据分析。结果：角膜塑形镜戴镜后光学治疗区中心主要呈颞下方向的中度偏心（0．5-1．0mm），各时间点偏心距离差异无统计学意义。角膜塑形镜戴镜后角膜总高阶像差、总三阶像差、总彗差均较术前显著增加（F=4．491、5．297、2．927，均P〈0．05）。戴镜后1．5年，偏心距离与角膜各像差变化值无相关性。戴镜后1．5年，眼轴较戴镜前显著延长（t=-0．725，P〈0．05），但眼轴变化值与偏心距离不相关。结论：角膜塑形镜戴镜后光学中心偏心距离在戴镜后1周达到稳定并可引起戴镜后早期角膜高阶像差增加，但在戴镜1．5年后光学治疗区中心偏心程度对眼轴发育无影响。

Objective： To study the dynamic effects of treatment zone decentration on corneal higher-order wavefront aberrations and axial length elongation after orthokeratology. Methods： This prospective study assessed corneal topography and wavefront aberrations before orthokeratology treatment and at 1 week, 6 months, and 1.5 years after overnight orthokeratology lens wear. Axial length elongation was evaluated before and after 1.5 years of treatment. Data were analyzed using Pearson correlation, repeated measurements ANOVA and paired t tests. Results： Decentration was located mainly in the inferior temporal quadrant. The magnitudes of deeentration at 1 week, 6 months, and 1.5 years after orthokeratology were locatedprincipally within 0.5-1.0 mm. There were no significant differences in the decentration magnitudes at the different follow-up visits after orthokeratology. The root mean squares （RMS） of the total corneal higher-order aberration, third-order aberration, and coma-like aberration were significantly increased by orthokeratology at 1 week, 6 months, and 1.5 years （F=4.491, 5.297, 2.927, P〈0.05）. Changes of aberrations were not correlated with the decentration at 1.5 years after orthokeratology. Axial length elongation was increased significantly at 1.5 years after orthokeratology （t=-0.725, P〈0.05）, but there was no significant correlation with the decentration. Conclusions： Decentration of the treatment zone became stable 1 week after orthokeratology, and it increased the corneal higher-order aberrations at an early stage. However, orthokeratology-induced decentration had no effect on axial length elongation up to 1.5 years.