Influence of corneal asphericity on the refractive outcome of intraocular lens implantation in cataract surgery

J Cataract Refract Surg. 2015 Apr;41(4):785-9. doi: 10.1016/j.jcrs.2014.07.035.


Purpose: To evaluate the possible influence of anterior corneal surface asphericity on the refractive outcomes in eyes having intraocular lens (IOL) implantation after cataract surgery.

Setting: Fondazione G.B. Bietti IRCCS, Rome, Italy.

Design: Retrospective comparative case series.

Methods: Intraocular lens power was calculated using the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. Asphericity (Q-value) was measured at 8.0 mm with a Placido-disk corneal topographer (Keratron), a rotating Scheimpflug camera (Pentacam), and a rotating Scheimpflug camera combined with Placido-disk corneal topography (Sirius). The relationship between the error in refraction prediction (ie, difference between expected refraction and refraction measured 1 month after surgery) and the Q-value was assessed by linear regression.

Results: The same IOL model (Acrysof SA60AT) was implanted in 115 eyes of 115 consecutive patients. Regression analysis showed a statistically significant relationship between the error in refraction prediction and the Q-value with all formulas and all devices. In all cases, a more negative Q-value (prolate cornea) was associated with a myopic outcome, whereas a more positive Q-value (oblate cornea) was associated with a hyperopic outcome. The highest coefficient of determination was detected between the Hoffer Q formula and the Placido-disk corneal topographer (R(2) = 0.2630), for which the error in refraction prediction (y) was related to the Q-value (x) according to the formula y = -0.2641 + 1.4589 × x.

Conclusion: Corneal asphericity influences the refractive outcomes of IOL implantation and should be taken into consideration when using third-generation IOL power formulas.

Financial disclosure: Dr. Hoffer receives book royalties from Slack, Inc., Thorofare, New Jersey, and formula royalties from all manufacturers using the Hoffer Q formula. No other author has a financial or proprietary interest in any material or method mentioned.

Publication types

  • Comparative Study

MeSH terms

  • Axial Length, Eye
  • Biometry
  • Cornea / pathology*
  • Corneal Topography
  • Humans
  • Lens Implantation, Intraocular*
  • Lenses, Intraocular
  • Optics and Photonics*
  • Phacoemulsification*
  • Refraction, Ocular / physiology*
  • Refractive Errors / diagnosis
  • Retrospective Studies