目的：对比观察高度近视儿童配戴离焦硬性透气性角膜接触镜(RGPCL)前后角膜屈光力改变，并分析配戴后镜片对角膜屈光力及散光量的影响。

方法：自身前后对照研究。收集2019-06/2020-06在西安市第一医院眼视光中心就诊并验配离焦RGPCL的8～12岁高度近视儿童30例60眼。使用TMS-4N角膜地形图仪测量基线及戴镜0.5、1a时戴镜状态下角膜切向屈光力，分析角膜鼻侧(N)、颞侧(T)、上方(S)和下方(I)角膜最大屈光力值及中央顶点处角膜屈光力改变情况，同时以1mm为间隔采集前述4个方位角膜屈光力以及角膜顶点处屈光力，采集范围为1～4mm，分析戴镜前后各点位屈光力变化情况。戴镜0.5，1a时后要求停戴1wk后复测眼轴、屈光度和角膜地形图，分析戴镜后较基线时眼轴、等效球镜度、散光和角膜屈光力等改变情况。

结果：配戴离焦RGPCL时鼻侧(N)、颞侧(T)、上方(S)和下方(I)的角膜最大屈光力在0.5、1a时较戴镜前均显著增加，与角膜顶点处屈光力相比均表现为正相对屈光力，与戴镜前的负相对屈光力相比具有显著差异。在戴镜0.5、1a时复诊时戴镜状态下角膜相对周边屈光力朝正屈光力方向改变，除T1点位周边负屈光力增加外，其余各轴向各点位周边屈光力均显著增加。配戴0.5a后角膜陡K值变平0.11±0.10D，simK值减少0.20±0.18D，1a后角膜陡K值变平0.10±0.12D，平均K值变平0.02±0.05D，simK值减少0.16±0.13D。戴镜0.5、1a时后角膜平K较基线变化无差异。

结论：配戴离焦RGPCL状态下角膜最大屈光力较角膜顶点处均表现为正相对屈光力，且4条轴向上各点位角膜相对周边负屈光力均由负值转变为正值。戴镜1a内眼轴和等效球镜度均较基线时增加，而散光量减少，角膜屈光力呈陡K变平趋势。

METHODS: Self-controlled before-after study. A total of 30 cases(60 eyes)of children aged 8-12, with high myopia who were treated and fitted with defocus RGPCL in the Optometry Center of Xi'an First Hospital from June 2019 to June 2020 were collected. Using TMS-4N corneal topography instrument to measure the corneal tangential refractive power at baseline and wearing lens for 0.5 and 1a, and analyze the nasal side(N), temporal side(T), superior(S)and inferior(I)of the maximum corneal refractive power values at the 4 axial directions and the changes of the corneal refractive power at the center were collected at the same time at 1 mm intervals. The changes of corneal refractive power at each point before and after wearing glasses were analyzed. The axial length, diopter and corneal topography were required to be measured after 0.5 and 1a, and the changes in axial length, spherical equivalent, astigmatism and corneal refraction compared with baseline were analyzed.

RESULTS: The maximum corneal refractive power of nasal(N), temporal(T), superior(S)and inferior(I)side was significantly increased at 0.5 and 1a when wearing defocus RGPCL compared with that before wearing glasses, which all showed positive relative refractive power compared with the corneal refractive power at center and was significantly different from the negative relative refractive power before wearing lenses. The relative peripheral refractive power of the cornea changed in the direction of positive refractive power when the lenses were worn for 0.5 and 1a. Except for the increase in the peripheral negative refractive power at the T1 point, the peripheral refractive power at all points in the other axes increased significantly. After wearing for 0.5a, the corneal steep K value became flat by 0.11±0.10D, the simK value decreased by 0.20±0.18D, the corneal steep K value became flat by 0.10±0.12D after 1a, the average K value became flat by 0.02±0.05D, and the simK value decreased by 0.16±0.13D. There was no significant difference in corneal level K from the baseline after wearing glasses for 0.5 and 1a.

CONCLUSIONS: The maximum refractive power of the cornea in the state of wearing defocus RGPCL is positive relative refractive power compared with the vertex of cornea, and the relative peripheral negative refractive power of the cornea at each point on the 4 axes changes from negative value to positive value. Within 1a of wearing glasses, the axial length and spherical equivalent increased compared with the baseline, while the amount of astigmatism decreased, and the corneal refractive power showed a trend of steep K and flattening.