Visual performance modeling following RK, PRK, and LASIK demonstrates the need for improved treatment algorithms

Refractive surgery has emerged as a means of correcting refractive error. A variety of techniques have been developed for modifying the dioptric power of the cornea, with varying degrees of success. Perhaps the most widespread techniques in use today are radial keratotomy (RK), photorefractive keratectomy (PRK), and laser in situ keratomileusis (LASIK). The goal of these procedures has been to reduce spherical and cylindrical refractive error. However, little attention has been devoted to visual distortions introduced by these procedures. Postoperative patients often complain about glare, halos, and difficulty seeing low contrast objects in dim lighting, even though they have 6/6 (20/20) vision. A fundamental understanding of the assessment of visual performance and the mechanisms behind these visual problems is useful for proper patient education and optimizing surgical techniques to alleviate the problems.