短期配戴角膜塑形镜对中央和周边角膜厚度的影响

目的观察过夜配戴角膜塑形镜3个月后中央和周边角膜厚度的变化。设计前瞻性病例系列。研究对象103例(197眼)近视患者,平均年龄(19.0±7.5)岁,平均等效球镜度(-3.25±0.91)D。方法过夜戴角膜塑形镜,采用眼前段分析仪(Pentacam)测量角膜厚度,观察配戴前后1天、1个月和3个月角膜中央和距中央半径1、2、3、4 mm处角膜厚度的变化。同时观察屈光度和角膜地形图中央角膜屈光力的变化。主要指标角膜厚度、等效球镜度、中央角膜屈光力。结果戴镜3个月后等效球镜度减少(-3.01±0.09)D,与戴镜前比较差异有统计学意义(P=0.00)。戴镜3个月后角膜中央屈光力减少(2.40±0.15)D,与戴镜前比较差异有统计学意义(P=0.00)。戴镜1天不同位点角膜厚度均增厚,中央区、半径1 mm、2 mm、3 mm、4 mm处角膜分别增厚(5.90±3.69)μm、(7.54±3.73)μm、(10.52±3.91)μm、(11.76±4.23)μm、(9.33±4.93)μm。戴镜1个月,中央、半径1 mm处厚度分别减少(-4.18±3.68)μm、(-0.50±3.73)μm;半径2、3、4 mm处角膜厚度分别增加(6.39±3.91)μm、(9.57±4.22)μm、(2.00±5.05)μm;戴镜3个月,中央、半径1 mm处角膜厚度分别减少(-6.61±3.67)μm、(-3.67±3.72)μm,半径2、3、4 mm处角膜厚度分别增加(3.05±3.90)μm、(6.42±4.21)μm、(5.63±4.94)μm。除半径4 mm位点以外,其他各角膜位点在不同配戴时间的角膜厚度变化均有统计学意义(P均<0.05)。中央角膜厚度随时间变化的速度快于周边角膜厚度(P=0.00)。结论短期配戴角膜塑形镜后角膜不同位点厚度的变化与角膜形状改变一致,中央角膜变薄,从旁中央半径2 mm开始角膜增厚。

The short-term effects of orthokeratologic lens on central and peripheral corneal thickness

Objective To observe the short-term changes of the central and peripheral corneal thickness after wearing orthokeratology （OK） contact lenses overnight. Design Prospective case series. Participants 103 patients （197 eyes） with myopia, average ages 19.0±7.5 years, average spherical equivalent refraction-3.25±0.91 diopters （D）. Methods All the patients wore orthokeratology lens overnight. The corneal thickness was measured with a rotating Scheimpflug camera （Pentacam） on different corneal areas, including central, peripheral corneal ring on radius 1 mm, 2 mm, 3 mm and 4 mm. The changes of spherical equivalent refraction and central corneal radius of corneal topography were measured also. All the examinations were done on baseline and 1 day, 1 month, 3 months after wearing OK. Main Outcome Measures Corneal thickness （CT）, spherical equivalent refraction （SER）, central corneal radius （CCR）. Results Compared with baseline, SER reduced -3.01±0.09 D in 3 months and CCR reduced 2.40±0.15 D （both P〈0.05）. After 1 night wearing, compared with pre-wearing CT increased 5.90±3.69 μm, 7.54±3.73 μm, 10.52±3.91 μm, 11.76±4.23 μm, 9.33±4.93 μm from the center, to radius 1 mm, 2 mm, 3 mm and 4 mm respectively （all P〈0.05）. After 1 month, CT reduced -4.18±3.68 μm and -0.50± 3.73 μm in the center and radius 1 mm respectively, but increased 6.39±3.91 μm,9.57±4.22 μm,2.00±5.05 μm in radius 2 mm, 3 mm, 4 mm, respectively. After 3 months, CT reduced -6.61±3.67 μm and -3.67±3.72 μm in the center and radius 1 mm respectively. But CT increased 3.05±3.90 μm, 6.42±4.21 μm, 5.63±4.94μm in radius 2 mm, 3 mm, 4 mm, respectively （all P〈0.05）. The central corneal thickness changed faster than peripheral corneal thickness in different time （P=-0.00）. Conclusion The changes of corneal thickness after wearing orthokeratology lenses are consistent with the changes of the shape of cornea. The central cornea becomes thin and the cornea from radius 2 mm to peripheral becomes thick.