Effect of central corneal thickness on surgically induced astigmatism in cataract surgery.

Objective: To evaluate the effect of central corneal thickness (CCT) on surgically induced astigmatism (SIA) in cataract surgery using temporal clear corneal incisions.

Methods: Department of Ophthalmology, Seoul National University Hospital, Seoul, Korea. Methods: The retrospective nonrandomized clinical study comprised 129 eyes that had cataract surgery performed through a sutureless temporal clear corneal incision. Eyes were categorized according to the axis of the preoperative astigmatism: against the rule (ATR, 0 to 45 degrees; n = 64) or with the rule (WTR, 46 to 90 degrees; n =65). Corneal topography was taken preoperatively and 1 day and 2 months postoperatively to evaluate the change in the cornea. The SIA was calculated using the polar method from simulated keratometric readings obtained with topography. Correlations between SIA and CCT were analyzed by linear regression analysis and compared between the ATR and the WTR groups.

Results: One day postoperatively, the SIA was negatively correlated with CCT in the ATR group but not in the WTR group (P =.050 versus P =.92; linear regression analysis). At 2 months, the correlation between CCT and SIA was no longer statistically significant.

Conclusions: Central corneal thickness was negatively correlated with the amount of SIA immediately postoperatively when the preoperative astigmatism was ATR. The correlation was not present 2 months after surgery. These results may be applied to abnormally thin corneas such as those after keratorefractive surgery.