A retrospective review of photorefractive keratectomy to enhance earlier radial keratotomy.

摘要

The idea of therapeutically targeting the underlying pathogenic mechanisms of keratoconus was explored in the 1990s by Khadem et al15 who pursued the identification of biological glues that could be activated by heat or light to increase the resistance of stromal collagen. It was discovered that the gluing effect was mediated by oxidative mechanisms associated with hydroxyl radical release. A similar mechanism related to active glycosylation of age-dependent tropocollagen was shown in aging corneas.16 The phenomenon of collagen cross-linking after ultraviolet-A (UVA) light exposure was reported by Klingman and Gebre17 in 1991 when the investigators observed biochemical changes in the skin of hairless mice after chronic exposure to UVA radiation. Their experiments rendered collagen highly resistant to pepsin digestion indicating increased collagen cross-linking induced by UVA.