IOL-Calculations using the Haigis-Formula in Patients with Relative anterior Mikrophthalmus (RAM)
G.U. Auffarth, T. U. Bartke, J. C. Uhl, M.R. Tetz
Background: Patients with relative anterior micropthtalmus (RAM) are characterized by special anatomical features (corneal diameters < 11 mm, shallow anterior chamber depth < 2 mm and normal axial length). Because of those anatomical parameters IOL calculation in this patient group sometimes is diffcult.
Patients and Methods: Twenty three patients with RAM aged 76.4 ± 8.0 years were evaluated for preoperative target refraction and postoperative refraction after cataract surgery. We used the Haigis-Formula for IOL power calculation.
Results: The average IOL power implanted was 25.7 ± 2.6 dptr. (one-piece all-PMMA-IOL). The preoperatively calculated target refraction was -0.3 ±1.37 dptr. (range: -3,1 to +2,1 dptr.). The postoperative spherical equivalent was on average 0.26 ± 1.03 dptr, (range 2.5 to +1.5 dptr.). The mean difference between target and end refraction was 0.13 ± 1.3 dptr . 70% of cases did not differ more than 1 diopter from target refraction, 78.3% not more than 2 diopters, no patient more than 3 diopters. There was no correlation between the amount of deviation target/end refraction and the axial length, corneal diameter and anterior chamber depth (p<0.2). There was, however, a significant correlation between target refraction and amount of deviation of spherical equivalent. The largest differences were found with target refractions > ± 2 diopters.
Conclusions: In spite of the special anatomical conditions in patients with RAM the Haiges-Formula produced reliable IOL power calculation values. The best accuracy was achieved when aiming at a target refraction in the range of ± 2diopters.
Dept. of Ophthalmology, Universily of Heidelberg, INF 400, 69120 Heidelberg