Postoperative astigmatism in the second eye undergoing cataract surgery.

OBJECTIVE

To predict postoperative refractive astigmatism in the second eye undergoing cataract surgery using standard biometry and information obtained from the first eye.

METHODS

We conducted a retrospective study of 160 patients undergoing bilateral sequential phacoemulsification with capsular bag implantation of a hydrophobic acrylic lens at a Veterans Affairs medical center. Keratometric and refractive astigmatism were described by Jackson cross cylinder with-the-rule (J(0)) and oblique (J(X)) components. Preoperative predictors of postoperative refractive astigmatism in the second eye were determined by multivariable regression.

RESULTS

The postoperative refractive astigmatism in the first eye predicted 40% of the variation in the second eye (r(2) = 0.40; P < .001). The multivariable model to predict postoperative with-the-rule astigmatism was J(0PostopEye2) = (0.376 × J(0PostopEye1)) + (0.327 × J(0KeratomEye2)) + (0.097 × J(0PreopEye2)) - 0.099 (P < .001 for first 2 terms; r(2) = 0.56). The multivariable model for oblique astigmatism was J(XPostopEye2) = (0.350 × J(XKeratomEye2)) + (0.231 × J(XKeratomEye1)) + (0.064 × J(XPreopEye2)) - 0.07 (P ≤ .01 for first 2 terms; r(2) = 0.20).

CONCLUSIONS

Refractive with-the-rule astigmatism observed postoperatively in the first eye is a strong independent predictor of postoperative with-the-rule astigmatism in the second eye. Keratometric oblique astigmatism in the first eye is a weak but statistically significant independent predictor of postoperative oblique astigmatism in the second eye. Both findings are consistent with mirror symmetry of the corneas about the midsagittal plane and may improve the prediction (and hence control) of postoperative astigmatism in the second eye.