Correction of pre-existing astigmatism during cataract surgery: comparison between the effects of opposite clear corneal incisions and a single clear corneal incision

Background: Opposite clear corneal incisions (OCCIs) have been reported to reduce pre-existing astigmatism ( PEA) during cataract surgery. Our goal was to evaluate the effect of OCCIs on correcting PEA in cataract surgery. Methods: Non-randomized prospective study. Thirty-four patients with PEA of greater than 1.5 diopters ( D) underwent clear cornea phacoemulsification cataract extraction with 3.2-mm OCCIs (OCCI group). The control group consisted of 23 successive patients with PEA < 1.5 D who underwent cataract extraction without OCCI. Best-corrected visual acuity, keratometry and refraction were recorded for all patients pre-operatively and post-operatively. Results: Using keratometric findings, mean astigmatism correction was 1.3 D ( +/-0.9 SD; decreased from 2.6 D pre-operatively to 1.4 D post-operatively) in the OCCI group but only 0.4 D in the control group ( P< 0.005), 8 months post-operatively. Vector analysis of astigmatism correction showed greater change for OCCI patients (1.8 D vs 1.0 D, P= 0.002). Using the Holladay method for calculating surgically induced refractive change (SIRC), the OCCI group showed a higher value of SIRC ( - 1.6 D vs - 0.97 D), but this was not statistically significant. The OCCI patients showed a greater and significant change in refraction spherical equivalent than the controls. No complications related to OCCI or cataract surgery occurred during the follow-up period. Conclusions: Opposite clear cornea incision seems to be a simple, predictable, safe and effective procedure in reducing preexisting corneal astigmatism in cataract surgery. It has an enhanced effect in correcting astigmatism compared to a single clear cornea incision when using keratometric findings value but not when using refractive data. Future studies are needed to document the long-term effect of OCCI and to evaluate the correlation between incisions of different size and astigmatism correction.