Evaluation of intraocular lens power after keratorefractive surgery by IOLMaster

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. Key words: Lenses,introcular ;  Refractions,ocular ;  Keratomileusis,laser in situ ;  Evaluation studies ;