Assessment Of Effects And Comparision Of Healing After PRK And LASEK In Rabbits

Objective: To observe effects and cornea! healing after PRK and LASER on rabbits and find whether and why LASEK is superior to PRK. Methods: Fifteen rabbits were randomly distributed into 5 groups. Each group had 6 eyes; PRK was performed on the 3 eyes, and LASEK was performed on the others. Corrections of +8.00 D were ablated. One group of rabbits was killed 1 day after surgery, and the corneas were selected for histopathological study and immunohistochemical study to examine cell apoptosis, Masson-trichroma and Alcian-blue and PAS staining. The left eyes were reexamined twice a day until the corneal epithelium were intact, and at 1 week, 2 weeks, 4 weeks and 6 weeks after surgery, refractive outcomes, comeal curvature values and depth, haze were recorded, then the eyes were enucleated for light microscope and Masson-trichroma and Alcian-blue and PAS staining.Results: In group LASEK, the healing time of cornea epithelial is shorter (0.6day) than PRK group (l.Sdays); 24 hours after operation, the amount of apoptosis cells in group LASEK (24.00+7.54) is higher than group PRK (13.67 ?2. 58); at any time, there is no significant difference in haze, optical power outcomes, corneal curvature values and pachymetry between group LASEK and group PRK, but curve diagrams show that the alteration is less in group LASEK than group PRK from 1 week to 6 weeks after surgery. There is significant myopic shift in group PRK 6 weeks later after operation, but in group LASEK, this phenomenon did not happen. HE stain and Masson-trichrome and PAS stain show that there is no "acellular zone", the collagen in superior matrix is fused and neutral mucosubstances covered the shallow anterior layer of the corneal stroma in 24h after LASEK operation; In 1 week after surgery, the collagen and the glycosaminbglycans in operation zone is compacted and the keratocytes increase; There is no difference after operation 2, 4 and 6 weeks between two groups. There is no positive stain with Alcian Blue in two groups. Conclusions: For correcting higher myopic, LASEK is superior to PRK. It maybe related to the whole corneal epithelial flap that slows the apoptosis and hastesthe wound healing.