Behaviour of Intraocular Lenses Implanted after Capsulorhexis and Envelope Capsulotomy. PART I: Postoperative IOL Displacement

Abstract

OBJECTIVE:To evaluate postoperative variation in loop situation and postoperative intraocular lens (IOL) displacement, i.e. the difference between early and late decentration and correlations with the type of capsulotomy, presence of tears in the anterior capsule, loop situation and type of IOL. STUDY DESIGN: Prospective study. The patients were examined in the first postoperative week and 6 months later. SETTING: Patients from the Red Cross Hospital and private patients of the senior author. PATIENTS: Patients operated on for extracapsular cataract extraction (ECCE) with posterior chamber IOL implantation. Envelope capsulotomy was performed in 147 eyes and capsulorhexis in 156 eyes. MAIN OUTCOME MEASURES: IOL decentration in relation to the centre of the cornea was measured in the first postoperative week and 6 months later. Gonioscopy was performed at the same time to determine the loop situation. RESULTS: Mean IOL displacement was −0.01 mm in the continuous curvilinear capsulotomy group without tears of the anterior capsule, −0.11 mm when there were tears in the anterior capsule and −0.19 mm in the envelope group (P < 0.01 between the capsulorhexis group without tears and the envelope group). With regard to the loop situation, mean postoperative IOL displacement was −0.02 mm for in-the-bag lenses and −0.73 for asymmetrically implanted lenses (P < 0.001). In the envelope capsulotomy group, 79% of the lenses were in-the-bag in the first postoperative week; of these 70% were still there 6 months later. In the capsulorhexis group with tears 86% were in-the-bag in the first week; of them 80% were still there at the sixth month. In the capsulorhexis group without tears 98% of the lenses were in-the-bag in the first week and all of them were still there 6 months later. CONCLUSIONS: The most important single factor affecting postoperative IOL stability was the absence of radial tears in the anterior capsule. This prevents the loops of the lens coming out of the bag, the cause (increased by postoperative fibrosis) of IOL displacement. In consequence, continuous curvilinear capsulotomy is the best capsulotomy technique, providing a perfect lens stability.