The Relationship between Corneal Opacity and Immunohistochemical Expression of Heat Shock Protein 72/73 after Excimer Laser Photorefractive Keratectomy

ABSTRACT

Excimer laser PRK (photorefractive keratectomy) for myopic correction provides an accurate correction in the cases of moderate myopia with a little side effect, but in high myopia it frequently causes corneal opacity and myopic regression. To determine the etiology of the corneal opacity, the author studied on the immunohistochemical stain for heat shock protein 72/73 after myopic excimer laser PRK. Thirty Newzealand white rabbits (60 eyes) were divided into four groups A, B, C, and control group. Myopic PRK was carried out on the cornea to correct the amounts of -6D myopia(group A), -9D(group B), and -15D(group C) with multizone technique using Excimer laser(VisX 20/20, Sunnyvale, USA). The corneal status was examined using a slit lamp. The eyes were enucleated at 6, 24, 48hours, 1 week and 8 weeks after operation. The corneas were obtained and sectioned for immunohistochemical stains. Corneal opacity was found with the mean density of 0.83(A group), 1(B group), and 1.67(C group) 8 weeks after the operation. Hsp 72 immunoreactive staining was noted in corneal epithelium in the C group at 24 hours after operation and maximal expression was found at 48 hours after operation. Hsp 73 was seen in corneal epithelium and stroma of all group. But maximal expression was observed in B and C groups 48 hours after operation. Consquently, the author believes that hsp 72/73 might be an important role of corneal haziness following PRK.