长期配戴软性角膜接触镜患者停戴后角膜厚度的变化

目的观察长期配戴软性角膜接触镜（soft contact lens,SCL）者摘镜后近期角膜中央厚度（central corneal thickness,CCT）的变化,从而为准分子激光手术时机的选择提供参考。方法应用超声角膜测厚仪,检测准分子激光原位角膜磨镶术（laser in situ keratomileusis,LASIK）的前长期配戴SCL（5年以上）的患者75例（150眼）,术前连续观察摘镜当天、摘镜后第3天、第1周、第2周和第1个月时的CCT。根据摘镜后第1周时的角膜地形图检查结果分为两组：组Ⅰ为角膜地形图正常组,共41例（82眼）;组Ⅱ为角膜地形图异常组,共34例（68眼）。对数据采用SPSS11.0统计学软件进行分析,采用配对t检验比较摘镜后不同时间的CCT的差异。结果两组患者摘镜后不同时间,角膜厚度均值随摘镜时间的延长呈下降趋势。与摘镜后1个月时的CCT值相比,组Ⅰ在摘镜当天和摘镜第3天时差异均有统计学意义（t=2.771,t=2.956,P〈0.01）,但摘镜第1周时差异已无统计学意义（t=3.076,P〉0.05）。而组Ⅱ在摘镜2周内各时间点,CCT 值与摘镜1个月比较,差异均有统计学意义（P〈0.05）。结论长期持续配戴SCL者接受LASIK手术,可以参考摘镜后第1周时的角膜地形图结果选择手术时机。角膜地形图正常者可在摘镜后第1～第2周时手术,根据1周后的CCT值计算角膜剩余基质床。角膜地形图异常者应延长观察时间。

Corneal thickness measurements after the discontinued use of long-term wear soft contacts lenses

Objective To evaluate corneal thickness changes when soft contact lenses（SCL） are removed after long-term wear in candidates for laser in situ keratomileusis（LASIK）.The timeline for corneal stability was investigated.Methods A total of seventy-five myopes（150 eyes） who had worn SCLs daily for at least five years were evaluated.Central corneal thickness（CCT） was measured with pachymetry immediately after lens removal and then repeated at 3 days,1 week,2 weeks and 1 month.Results SCL wearers had a mean reduction in CCT.Compared to the results at one month,CCT was stable after 1 week in group Ⅰ（corneal topography normal and regular,t =1.076,P 〉0.05）.But the mean CCT on the final visit was unstable in group Ⅱ（abnormal corneal topography,t= 2.676,P〈0.05））.Conclusion SCL wear should be discontinued at least 1 week before LASIK if corneal topography is normal.However,removal 2 weeks before LASIK seems to be inadequate for patients with abnormal corneal topography.Topography and pachymetry may be better methods for determining ocular stability before LASIK.