配戴SCL在摘镜后多久才能恢复正常形态呢?有关的文献报道不尽相同,角膜厚度的变化与戴镜方式和戴镜时间有关[11-13]。Braun等[12]观察发现SCL配戴者的角膜厚度比对照组低22 ?滋m(P=0.000)。Nourouzi等[13]对100只日戴SCL眼摘镜后的角膜厚度变化进行了连续6个月的观察,发现角膜厚度稳定时间为2~15 d,有74%的患者在1周内稳定,26%在2周内稳定,年龄大者恢复较慢。Ng等[14]观察发现,角膜地形图结合角膜厚度测量,是屈光手术前观察SCL摘镜后角膜稳定性恢复的最佳方法。
对于行LASIK的患者,我们通常认为角膜在SCL摘镜1~2周后已基本恢复正常,可以行手术治疗[3]。因此,本组观察根据每眼摘镜后第1周时的角膜地形图检查结果进行分组,组Ⅰ为角膜地形图正常组(双眼中央角膜屈光力<47 D,角膜曲率对称且差值≤1.5 D,I-S值≤1.25 D,泪膜均匀),CCT在1周时已趋于稳定。组Ⅱ为角膜地形图异常组(以上指标有一项或一项以上异常),CCT在摘镜1个月时仍然不稳定,尤其是当角膜地形图呈现“假性圆锥”时,需要更长时间的观察。
本研究结果显示,对于配戴SCL者的手术时机,可参照角膜地形图、角膜厚度等因素综合考虑。摘镜后2周可能是角膜恢复塑型的关键时期,而对于预期角膜切削量大、角膜偏薄、拟行个体化切削者,应延长观察期。
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