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.