Influence of ocular features and incision width on surgically induced astigmatism after cataract surgery

To identify factors associated with surgically induced astigmatism (SIA) following phacoemulsification.

Six hundred five eyes underwent phacoemulsification with a 2.2-mm (the 2.2-mm group, n = 248) or 2.75-mm (the 2.75-mm group, n = 357) superior limbal incision. Preoperative axial length, anterior chamber depth, corneal curvature, and intra-ocular pressure were measured. Corneal curvature and intraocular pressure were measured at 1 day, 1 week, and 1, 2, and 3 months postoperatively. SIA, corneal flattening, and torque were calculated using the Alpins method. The effect of preoperative corneal astigmatism meridian on SIA was also examined. Differences in SIA between the 2.2- and 2.75-mm groups were explored, and correlations between SIA and preoperative corneal astigmatism, anterior chamber depth, axial length, age, and intraocular pressure were analyzed.

SIA, corneal flattening, and torque were smaller in the 2.2-mm group than in the 2.75-mm group at 1 week (P = .003, .006, and .014, respectively), but not statistically different thereafter. Higher preoperative corneal astigmatism, older age, and shallower anterior chamber depth were associated with greater SIA in both groups. The effect of astigmatism meridian on SIA was more noticeable in the 2.75-mm group. Shorter axial length and lower intraocular pressures were associated with greater SIA in the 2.75-mm group but not in the 2.2-mm group.

Reducing limbal incision width and considering patient age, the meridian and magnitude of corneal astigmatism, anterior chamber depth, axial length, and intraocular pressure, and adjusting the flattening component of SIA input for toric intraocular lens power calculation could potentially improve the astigmatism control in refractive lens surgery.