近视眼准分子激光术后远期干眼症的影响因素及相关性分析

Risk factors to dry eye long-term after excimer laser eye surgery for myopia

目的研究准分子激光近视矫正术后远期干眼症的主要危险因素。方法回顾性分析行准分子激光近视矫正术的3组患者[其中准分子激光角膜切削术（PRK）组29例（58眼）、角膜瓣蒂位于鼻侧的准分子激光原位角膜磨镶术（N—H—LASIK）组51例（102眼）、角膜瓣蒂位于上方的LASIK（S—H—LASIK）组13例（26眼）]的临床资料。分析比较3组患者术后出现干眼症相关指标[包括末次随访等效球镜、角膜曲率以及角膜切削厚度、残留角膜厚度、中央角膜敏感度（CCS）、基础泪液分泌试验（STI）和泪膜破裂时间（BUT）等]异常的中位时间以及3年无干眼并发症的发生率，并应用COX回归模型分析上述指标的影响因素。结果生存分析结果表明，三种术式下出现CCS、STI、BUT异常的中位时间以及3年无干眼并发症的发生率，两两比较差异均有统计学意义（均P〈0．05）；而且无上述干眼症指标异常的中位时间均为PRK最长、S—H—LASIK最短，3年无干眼并发症的发生率也均为PRK最高、S—H—LASIK最短。准分子激光角膜屈光手术后，CCS出现异常的危险因素主要有年龄、术前等效球镜、术前平均角膜曲率、随访时角膜曲率、角膜切削厚度以及手术方式；STI出现异常的危险因素主要有眼别、术前平均角膜曲率以及手术方式：BUT出现异常的危险因素主要有性别、年龄、术前等效球镜、术前平均角膜曲率、角膜切削厚度以及手术方式。结论近视激光手术可导致术后远期干眼症的发生，相对于PRK，LASIK尤其是S—H—LASIK是术后干眼症发生的高危因素，另外术中激光切削的角膜组织的面积和深度也是术后干眼症发生的高危因素。

Objective To investigate the related risk factors to dry eye long-term after the myopic correction by excimer laser eye surgery. Methods This retrospective study included three different groups of patients having myopic LASIK surgery （58 eyes of 29 cases were treated with photorefractive keratectomy （PRK） and 102 eyes of 51 cases received LASIK with a nasal-hinged flap （N-H-LASIK） procedure, while LASIK with a superior-hinged flap（S-H-LASIK） procedure was performed on the other 26 eyes. The abnormal median time of related signs of dry eye [central corneal sensitivity （CCS） ,fluorescine tear film breakup time （BUT）and Schirmer＇s baseline tear secretion test （ST I ） ] and the incidence of no occurance of dry eye in 3 years were analysed. COX regression was used to observe the factors that might affect these signs of dry eye. Results The survival analysis showed that the difference in median survival time of positive cases in CCS,ST I and BUT tests ,and the incidence of negative cases of dry eye in 3 years between PRK group, N-H-LASI group, and S-H-LASIK group were statistically significant, respectively （P〈0.05）. PRK showed mildest influence to either of CCS,ST I and BUT tests, while S-H-LASIK showed severest influence to either of them. The factors that mainly contribute to the change of CCS involved the patient＇s age, the preoperative spherical equivalent, the average corneal curvature pre-op, postoperative corneal curvature, the thickness of ablated cornea and the surgery procedure. The factors that mainly contribute to the change of BUT involved sex,age,the preoperative spherical equivalent,the average corneal curvature pre-op, the thickness of ablated corneal and the surgery procedure. The factors that mainly contribute to the change of ST I involved the average corneal curvature pre-op and the surgery procedure. Conclusion The excimer laser eye surgery for myopia could affect the incidence of dry eye. Compared with PPK, S-H-LASIK procedure should be considered as a high risk factor that contributes to dry eye long term postoperation. In addition to this reason, other risk factors are those mainly associated with the size and depth of corneal tissue that were cut during the procedure.