Custom selection of aspheric intraocular lenses after wavefront-guided myopic photorefractive keratectomy.

PURPOSE

To determine the optimum amount of spherical aberration in an intraocular lens (IOL) to maximize optical quality after previous wavefront-guided myopic photorefractive keratectomy (PRK).

SETTING

Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA.

METHODS

Aspheric IOL implantation was simulated in 102 eyes of 77 patients. The amount of spherical aberration in the IOL was varied to produce residual ocular spherical aberration from -0.50 to +0.50 microm. Using ZernikeTool software, the polychromatic point-spread function with Stiles-Crawford effect was calculated for residual ocular higher-order aberrations (HOAs) (3rd to 6th order) for 4.0 mm and 6.0 mm pupils and defocus of 0.00 diopter (D), -0.50 D, and +0.50 D. The IOL spherical aberration at which maximum image quality was achieved was determined. Stepwise multiple regression analysis was performed to assess the predictors of optimum IOL spherical aberration.

RESULTS

With 0.00 D, -0.50 D, and +0.50 D defocus, respectively, the mean optimum IOL spherical aberration (6.0 mm) ranged from -0.49 to -0.42 microm, -0.22 to -0.18 microm, and -0.75 to -0.64 microm (6.0 mm pupil) and from -0.34 to -0.20 microm, +0.08 to +0.44 microm, and -1.12 to -0.83 microm (4.0 mm pupil). Of the Zernike terms that significantly predicted optimum IOL spherical aberration, 4th-order spherical aberration Z(4,0) made the greatest contribution, followed by the 6th-order spherical aberration Z(6,0).

CONCLUSION

The amount of IOL spherical aberration producing the best image quality after previous myopic wavefront-guided PRK varied widely and could be predicted based on the full spectrum of corneal HOAs.