角膜屈光手术后人工晶状体屈光度数的IOLMaster评估

Evaluation of intraocular lens power after keratorefractive surgery by IOLMaster

目的 利用IOLMaster对比分析准分子激光角膜屈光手术后眼人工晶状体（IOL）屈光度的不同预测公式的准确性,以期为临床合理地计算IOL的度数提供客观资料.方法 根据眼轴长度将进行准分子激光角膜屈光手术的患者111例（222只眼）分为两组,A组59例（118眼）,眼轴长度24.00～26.09 mm,B组52例（104只眼）,眼轴长度26.10～29.00 mm.应用光学相干生物测量仪（IOL-Master）分别测量手术前后眼轴长度、角膜曲率、前房深度,并通过其提供的SRK-Ⅱ、SRK/T、Hoffer Q、Holladay、Haigis-L公式及临床病史法预测角膜屈光手术后IOL的度数.采用t检验对数据进行统计学分析.结果 术后角膜曲率为（37.10±0.34）mm,比术前明显减少（t=12.10,P＜0.01）,而眼轴长度、前房深度的差异均无统计学意义（t=0.54,1.21;P＞0.05）.术后两组Haigis-L公式测得的IOL度数分别为（24.13±0.36）和（23.88±0.41）D,比其他公式测得的IOL度数明显偏大.其中,Haigis公式与Haigis-L公式测得的数值差别最小,SRK-Ⅱ公式与Haigis-L公式测得的数值差别最大.术后A组、B组中各种公式的临床病史法测得的IOL度数均比原公式测得的数值大,SRK-Ⅱ公式A组差异无统计学意义（t=-1.54,P＞0.05）,其余公式A、B组差异均有统计学意义（t值范围-3.78～-3.20,P＜0.01）.术后各组中Haigis-L公式测得的IOL度数均比临床病史法测得的数值要大,但其中Hoffer Q临床病史法A组、Haigis临床病史法A组、Haigis-L临床病史法与Haigis-L公式测得的数值相比较差异无统计学意义（t=0.00,-1.73,0.00;P＞0.05）,而其他公式临床病史法与Hai gis-L公式测得的值差异有统计学意义.结论 利用IOLMaster评估现有的IOL测量公式对准分子激光屈光性角膜手术后人工晶状体度数的预测发现屈光度均趋于偏小（包括其临床病史法）,参考临床常用公式与Haigis-L公式预测的人工晶状体度数差值有助于临床提高角膜屈光手术后IOL度数预测的准确性.而对于Haigis-L公式预测得到的人工晶状体屈光度数的精确性尚需临床积累更大量的角膜屈光术后行白内障手术眼的样本量来进一步证实.

Objective To study the accuracy of different formulas predicting intraocular lens （IOL） power after excimer laser keratorefractive surgery in order to calculate the diopter of IOL accurately in the clinical practice. Methods One hundred and eleven cases （222 eyes） were collected in this study and were divided into two groups （A and B） according to their axial length. Fifty-nine cases （ 118 eyes） with axial lengths of 24-26 mm were taken as group A, and 52 cases （ 104 eyes） with axial length of more than 26 mm were taken as group B. All of the subjects enrolled in this study were examined by the IOL-Master before and after LASIK, including the axial length, corneal curvature, anterior chamber depth （ ACD）, and the IOL power which was predicted by the SRK-Ⅱ、SRK/T, Hoffer Q, Holladay, Haigis-L formulas and the Clinical History method offered by IOL-Master. The significance of the differences was analyeed by using student＇s t-test. Results The corneal curvature after LASIK decreased significantly （t = 12. 10,P 〈 0. 01 ）;the length of axis and ACD also decreased but had no significant differences as compared with pre-operation.The IOL powers of the two groups offered by the Haigis-L formula were significantly more than that offered by other formulas （t =0. 54,1.21 ,P 〈0. 01 ）. The difference between the Haigis and Haigis-L formulas was the smallest, and the difference between the SRK-Ⅱ and Haigis-L formula was the greatest. The IOL powers offered by the clinical history method were higher than that offered by these formulas; the differences were significant in both group A and group B, except the group A in SRK-Ⅱ （t =0. 00, -1. 73,0. 00,P 〈0. 01 ） The IOL powers offered by Haigis-L were greater than that from the clinical history method or other formulas and showed significant differences except that between Haigis-L and CH-Haigis or CH-Haigis-L formula （ P 〈 0. 01 ）. Conclusions Taking into consideration the difference of IOL power offered by HaigisL formula as compared with other current formulas, evaluation by IOL-Master will be helpful for improving the accuracy of IOL power prediction for the cataract eyes receiving corneal refractive surgery. However, the accuracy of the Haigis-L formula for eyes after corneal refractive surgery still requires to be confirmed by a further series of clinic data.