配戴角膜塑形镜后离焦环距离角膜缘宽度对控制近视的影响

目的：观察配戴角膜塑形镜后离焦环距离角膜边缘不同宽度对控制和减缓近视进展的影响。

方法：回顾性临床病例对照研究。选取2014-01/2015-12在我院视光学中心配戴角膜塑形镜的近视患者45例85眼，依据镜片覆盖角膜白到白横径的90%～95%确定镜片总直径，角膜横径12.1～13.00mm的患者选择镜片总直径11.0～11.2mm(A组)； 角膜横径11.1～12.0mm的患者选择镜片总直径10.5～10.9mm(B组)； 角膜横径10.0～11.0mm的患者选择镜片总直径10.0～10.4mm(C组)。观察三组患者戴镜前和戴镜1、2a等效球镜度数和眼轴的变化情况。

结果：戴镜前，三组患者年龄、等效球镜度、眼轴差异均无统计学意义(P>0.05)。戴镜1、2a，A组和B组患者等效球镜度和眼轴较戴镜前变化较小，差异均无统计学意义(P>0.05)，C组患者等效球镜度和眼轴较戴镜前显著增加，差异均有统计学意义(P<0.05)，且A组和B组患者等效球镜度和眼轴分别与C组比较，差异均有统计学意义(P<0.05)。

结论：配戴角膜塑形镜后离焦环距离角膜边缘的宽度不同对于控制和减缓近视的效果不尽相同，离焦环越靠近角膜边缘，近视的控制效果相对越弱。

Effect of different position of defocus ring on cornea of orthokeratology for myopia control

AIM:To observe the different effect of controlling myopia by orthokeratopraxis with different width between defocus circle and the rim around the cornea.

METHODS: A retrospective case-control study. A total of 45 patients(85 eyes)who came to our hospital for orthokeratopraxis lens fitting during January 2014 to December 2015 were selected. The diameter of the orthokeratopraxis lens was 90%-95% of the diameter of the cornea. So the patients were divided into three groups according to the different diameter of the orthokeratopraxis lens. The diameter of the orthokeratopraxis lens for the patients whose corneal diameter was between 12.1 to 13.00mm was 11.0-11.2mm(Group A). The diameter of the orthokeratopraxis lens for the patients whose corneal diameter was between 11.1-12.00mm was 10.5-10.9mm(Group B). The diameter of the orthokeratopraxis lens for the patients whose corneal diameter was between 10.0-11.00mm was 10.0-10.4mm(Group C). The change of the spherical equivalent(SE)and axial length(AL)were analyzed after wearing the lens for 1a and 2a.

RESULTS: Before wearing lens, the age, SE(D)and AL(mm)was not statistically significant in the three groups(P>0.05). After wearing lens for 1a and 2a, the change of SE(D)and AL(mm)was not statistically significant in Group A and Group B(P>0.05)and the change was statistically significant in Group C(P<0.05). The change of the SE and AL was also significantly different between Group A and Group C after wearing orthokeratopraxis lens for 2a(P<0.05). A similar result was found between Group B and Group C(P<0.05).

CONCLUSION: The effect of controlling myopia by orthokeratopraxis with different position of defocus circle on cornea is different. The position of defocus circle is more close to the corneal limbus, the effect is weaker.