Surgically induced astigmatism. A comparison of different cataract incisions and closures.

A single center, single surgeon, nonrandomized, prospective clinical trial was performed comparing the keratometric induced astigmatism by different types of incisions and closures, one day, one week, one month and three months after 255 cataract surgeries. After phacoemulsification, or in rare cases after extracapsular cataract extraction, through a scleral pocket or limbal incision, patients received either a 5 x 6 mm, 5.5 mm, or 6 mm diameter polymethylmethacrylate optic posterior chamber intraocular lens. Incision was closed with either none, one horizontal or radial, or running 10-0 nylon suture. Vector analysis calculations of prism diopters of mean postoperative-induced keratometric astigmatism showed a trend to lesser values at each interval in scleral pocket incisions but statistically significant difference only at 1 day and 1 week between 9-mm and 6-mm limbal, and 5-mm and 6-mm scleral pocket incisions. Other subgroup analyses, including incision shape and distance from limbus, and type of suture, did not reach statistical significance. Horizontal, 5-mm, sutureless scleral tunnel incision showed less induced astigmatism with more rapid stable refraction.