Accuracy of preoperative biometry in vitrectomy combined with cataract surgery for patients with epiretinal membranes and macular holes Results of a prospective controlled clinical trial

PURPOSE: To evaluate how adding vitrectomy to cataract surgery affects the accuracy of preoperative biometry and postoperative refractive outcomes. SETTING: Department of Ophthalmology, Ludwig Boltzmann Institute of Retinology and Biomicroscopic Lasersurgery, Rudolf Foundation Clinic, Vienna, Austria. METHODS: This study comprised 40 patients with vitreoretinal pathology and coexisting significant cataract (study group) and 40 patients with significant cataract only (control group). The main outcome measure was intraocular lens (IOL) power prediction error. Secondary outcome measures were spherical equivalent, anterior chamber depth, axial length, keratometry values, and intraocular pressure. A multivariate regression analysis was performed. RESULTS: There was a significant difference in prediction error between the study group and control group (P <.05). The addition of vitrectomy was associated with induced myopia of approximately -0.4 diopter, more so in patients who had epiretinal membrane removal than in patients with macular hole surgery (P = .04). There was no significant difference in prediction error between the 3 IOLs used (P = .2). CONCLUSION: The myopic shift was strongly dependent on the diagnosis and the need for intraocular tamponade, indicating that a slightly hyperopic IOL should be used in patients having combined surgery.