Outcome of adjustment for posterior corneal curvature in toric intraocular lens calculation and selection.

PURPOSE: To evaluate the accuracy of the cylinder power choice and the astigmatic refractive outcome for toric intraocular lenses (IOLs), the cylinder power of which was calculated using the Goggin nomogram that allows for the likely effect of posterior corneal astigmatism.

SETTING

The Queen Elizabeth Hospital, Adelaide, Australia.

DESIGN

Observational case series.

METHODS

The absolute value of the prediction error of the toric IOL cylinder power effect in consecutive eyes with preoperative anterior keratometric cylinder values of 1.0 diopter (D) or more was compared with the absolute value of the prediction error in a historical control group. The anteriorly measured keratometric cylinder values were altered by 2 coefficients of adjustment, one for with-the-rule eyes and one for against-the-rule eyes, before calculation of the IOL cylinder power to be implanted. In the controls, unadjusted keratometric cylinder values were used.

RESULTS

The case-series group comprised 31 eyes (29 patients) and the control group, 65 eyes. The absolute error in prediction of the toric IOL cylinder power effect was reduced from a median of 0.45 D (95% confidence interval [CI], 0.33-0.58) in the controls to a median of 0.23 D (95% CI, 0.13-0.35) in the adjusted eyes (P = .004).

CONCLUSION

Adjustment of toric IOL cylinder power by application of a coefficient of adjustment to anteriorly measured keratometric cylinder values based on the keratometric rule of the eye led to a clinically and statistically significant improvement in refractive astigmatic outcome.

FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.