All this combined with the seeming multitude of new keratorefractive procedures led to development of a new bona fide ophthalmic surgical subspecialty, controversial, as it may appear, called refractive surgery. Basic needs of refractive surgery are accuracy, stability, safety, and quality of vision. Several studies have shown that, for quality of vision, unoperated cornea is optically superior to operated cornea. Any operation on cornea creates abnormal contours, which in turn create optical aberrations. The greater the correction the more the decrease in quality of vision especially in low-contrast situations such as driving at night.
CLE is clearly an optically superior choice in most situations.
Finally, safety is discussed more extensively below. Almost all operable tissues and spaces of the eye have been investigated as locations for refractive surgical modulation, corneal surface, corneal stroma, anterior chamber, pupil, posterior chamber, lens, and sclera. Therefore, the lens assumes its role among others as a popular location for surgical refractive modulation for those who prefer a familiar procedure that spares the cornea and saves economic expense of an excimer. Those who decry lenticular approach emphasize all potential intraoperative and postoperative complications attendant with invasive intraocular procedures. Despite the controversy, clear lens replacement is a viable procedure for both myopia and hyperopia, and toric IOLs are now available for intraocular correction of astigmatism.