PRK、LASIK术后非接触眼压测量值的准确性

Accuracy of noncontact tonometry after PRK and LASIK

目的 :评估准分子激光屈光性角膜切削术 (PRK)和准分子激光原位角膜磨镶术 (LASIK)后非接触眼压 (NCT)测量值的准确性。方法 :对 5 5例 (10 9只眼 )行PRK和 5 7例(113只眼 )行LASIK的近视患者进行回顾性分析 ,手术前、后采用非接触眼压计测量患者的眼压 ,并测量角膜厚度和角膜曲率 ,进行统计学分析。术后随访时间 >1年 ,停用激素至少半年以上。结果 :PRK和LASIK术后NCT测量值都低于术前 ,分别下降 (3.6 7± 1.6 5 )mmHg和 (5 .11± 1.5 1)mmHg ,差异有非常显著意义 (P <0 .0 0 1)。PRK和LASIK术前眼压测量值与角膜厚度均呈高度正相关 (P <0 .0 0 1) ;术后眼压测量值的降低与角膜厚度的减少高度正相关 (P <0 .0 5 ) ,其回归方程分别为 ^Y(手术前、后眼压差 ,mmHg) =1.36 1+0 .0 38X(手术前、后角膜厚度差 ,μm)和 ^Y =1.95 4 +0 .0 4 0X ;眼压测量下降值和角膜曲率的降低无关。结论 :PRK和LASIK术后眼压测量值均低于术前 ,角膜厚度是导致手术后眼压测量值减少的主要因素 ,且眼压测量值随角膜厚度的减少而下降。在临床工作中 ,应避免术后类固醇性青光眼因眼压测量值的下降而被漏诊。

Objective:To assess the accuracy of noncontact tonometry after PRK and LASIK.Methods:55 patients(109 eyes) who had photorefractive keratectomy(PRK) and 57 patients(113 eyes) who had laser in situ keratomileusis(LASIK) performed by the same surgeon were reviewed retrospectively. All patients had discontinued steroid use for at least 6 months postoperatively and were thus eligible for evaluation of preoperative and postoperative intraocular pressure(IOP). Corneal thickness(pachymetry) and corneal topography were evaluated.Results:Preoperative and postoperative data showed that the mean decrease in the measured IOP was(3.67±1.65)mmHg (P<0.001) after PRK and(5.11±1.51)mmHg (P<0.001) after LASIK,and pachymetry was related to IOP measurement with NCT(P<0.001). No group(PRK or LASIK) had NCT values associated with central corneal curvature values nor decreased NCT values associated with decreased corneal curvature values. Regression analyses indicated that in both groups the decreased NCT values were higher in the eyes that had thicker corneas ablated(P<0.05).Conclusion:Corneal refractive surgery changed the accuracy of the NCT,causing it to underestimate IOP. The reduction was not correlated with the flattening of the central cornea. Decreased NCT values were due to decreased corneal thickness. When evaluating IOP after surgery,this possibility should be carefully investigated.[