High anterior corneal eccentricity, surgically induced astigmatism linked

Ophthalmic Surg Lasers Imaging. 2011;42(5):408-415.

The three factors most likely to contribute to postoperative astigmatism after cataract surgery were high anterior corneal eccentricity, high preop astigmatism and superior location of the main incision, a study found.

The prospective analysis examined 125 eyes of 87 patients after uneventful phacoemulsification surgery by a single surgeon between September 2008 and May 2009.

Superior location of the main incision led to the greatest surgically induced astigmatism, 0.82 D, according to the study. Surgically induced astigmatism was 0.63 D for superior-temporal location, 0.55 D for nasal location, 0.5 D for superior-nasal location, and 0.45 D for temporal location.

Of the 25 eyes showing surgically induced astigmatism of 1 D or greater, 21 had superior incision locations. About one-third of superior incisions resulted in astigmatism of 1 D or more.

Significant positive correlations were also observed between amount of surgically induced astigmatism and both preop anterior corneal eccentricity and preop corneal cylinder power (both P < .001).

"As demonstrated in this study, many factors may affect [surgically induced astigmatism] in cataract surgery," the study authors wrote. "Therefore, a careful examination of the refractive characteristic of the cornea will increase the accuracy of control of optical aberrations after the cataract surgery."