Keratocyte apoptosis and corneal antioxidant enzyme activities after refractive corneal surgery

Abstract

and corneal antioxidant enzyme activities after refractive corneal surgery AbstractPurpose Refractive corneal surgery induces keratocyte apoptosis and generates reactive oxygen radicals (ROS) in the cornea. The purpose of the present study is to evaluate the correlation between keratocyte apoptosis and corneal antioxidant enzyme activities after different refractive surgical procedures in rabbits. Methods Rabbits were divided into six groups. All groups were compared with the control group (Group 1), after epithelial scraping (Group 2), epithelial scrape and photorefractive keratectomy (PRK) (traditional PRK: Group 3), transepithelial PRK (Group 4), creation of a corneal flap with microkeratome (Group 5) and laserassisted in situ keratomileusis (LASIK, Group 6). Terminal deoxyribonucleotidyl transferase-mediated dUTP-digoxigenin nickend labelling assay (to detect DNA fragmentation in situ) and light microscopy were used to detect apoptosis in rabbit eyes. Glutathione peroxidase (Gpx) and superoxide dismutase (SOD) activities of the corneal tissues were measured with spectrophotometric methods. Results Corneal Gpx and SOD activities decreased significantly in all groups when compared with the control group (PϽ0.05) and groups 2, 3 and 6 showed a significantly higher amount of keratocyte apoptosis (PϽ0.05). Not only a negative correlation was observed between corneal SOD activity and keratocyte apoptosis (cc: ؊0.3648) but Gpx activity also showed negative correlation with keratocyte apoptosis (cc: ؊0.3587). Conclusion The present study illustrates the negative correlation between keratocyte apoptosis and corneal antioxidant enzyme activities. This finding suggests that ROS may be partly responsible for keratocyte apoptosis after refractive surgery.

Effect of linoleic acid and γ-linolenic acid on tear production, tear clearance and on the ocular surface after photorefractive keratectomy

“…Physical abrasion, following on from reduced tearing, stimulates the cells in the conjunctival epithelium to produce various cytokines (IL-1, IL-6, IL-8 and TNF-α) which then flow inside a tear film relatively deprived of protection factors, such as EGF and retinol. This stimulates apoptosis of the keratocytes [33,35], which is also stimulated by the release of reactive oxygen species induced by surgery on the cornea [3]. Apoptosis is of course the first essential step of epithelial healing [34], but it may also be a contributing factor in the frequent occurrence of a reduction in refraction or post-operative haze [19,28].…”

Effect of Basic Fibroblast Growth Factor in Transgenic Mice: Corneal Epithelial Healing Process after Excimer Laser Photoablation

“…The oxygen-free-radical-induced tissue damage after PRK is well documented [9,10,11,12,13,14,15,16,17]. …”

Role of Cysteine in Corneal Wound Healing after Photorefractive Keratectomy

“…The lipid peroxidation in the superficial corneal stroma is generated by oxygen free radicals, and it induces alterations in cellular proteins and membranes. This type of acute injury is responsible in part for corneal haze because of the apoptosis of keratocytes [26,27] . Many studies have revealed that excimer laser UV radiation decreases the detoxifying activity of the glutathione peroxidase enzyme, which is the main component of the corneal antioxidant system [28,29] .…”