A Superior Linear Oblique Scleral Incision for Controlled Astigmatism in Phacoemulsification Cataract Surgery

Abstract

Objective: To assess the control of postoperative corneal astigmatism in phacoemulsification cataract surgery performed with an oblique incision (forming an angle of 19–23° with the horizontal corneal meridian). Study Design: The length of the oblique incision was 7 mm in order to permit the insertion of a 7 mm optic intraocular lens; one end of the incision is 0.5–1 mm from the limbus and the other 3.5 mm. A prospective study on astigmatic changes at 10 davs, 1 month and 3 and 6 months after surgery was carried out. The explanation of the effect of the oblique incision on the cornea was based on a theoretical model. Setting: University Eye Clinic, Ioannina, Greece. Patients: 64 adults (65 eyes) underwent phacoemulsification cataract operation performed with our oblique incision. Main Outcome Measures: Keratometry before and after surgery to measure corneal astigmatism. Surgically induced astigmatism (SIA) was calculated using the vector method. RESULTS: The SIA in diopters (mean ± SD) was 1.13 ± 0.70 at 10 days, 0.97 ± 0.54 at 1 month, 0.99 ± 0.65 at 3 months and 1.0 ± 0.60 at 6 months indicating that significant changes in the cornea curvature happen before or during the first 10 days. The postoperative corneal astigmatism in diopters (mean ± SD) was 1.30 ± 0.84 at 10 days, 1.17 ± 0.64 at 1 month, 1.11 ± 0.47 at 3 months and 1.03 ± 0.46 at 6 months. No significant changes were observed after the first postoperative month. Conclusion: The postoperative corneal astigmatism, when performing the recommended oblique incision, is low and stabilizes by the first month due to a low and practically stable SIA after the first 10 days. Our experience also showed that after performing the oblique incision the use of the phacoemulsification probe is easy, facilitating the transition from classical extracapsular cataract extraction to phacoemulsification.