| Objective: The corneal wound healing effects the operative results after refractive surgery. Cytokine are a group of active and multi-functional peptides, which play important role in the corneal wound healing. This experiment investigate the expression of TGF- B1 and bFGF in the rabbet corneas to find whether such expression contribute to the corneal wound healing after PRK; and compare the effects of mechanical deepithelialization with chemical deepithelialization PRK on the corneal wound healing.Methods: Twenty-seven adult rabbits were employed in this study. Twenty-four rabbits were allocated to mechanical deepithelialization in one eye and chemical deepithelialization in the other eye before PRK. Correction of-8.00D were ablated. At 1, 7, 30 and 90 days after operation, the corneas were examined by slip-lamp microscopy for haze formation, and 6 rabbits were randomly selected for each time point to be enucleated, and corneas to be bisected. One half of each cornea was evaluated for TGF-β1, bFGFmRNA by the reverse-transcription PCR, and the other half was evaluated using both light microscopy and immunohistochemical staining for TGF B1 and bFGF.Results:1. The 1-2 degrees corneal haze was observed and haze in the mechanical groups were less than in the chemical groups(P<0.01) at 7d after mechanical and chemical epithelial deepithelialization PRK; at the 30d, the corneal haze was the most serious after mechanical and chemical epithelial deepithelializationPRK about 2-3 degrees; at the 90d, the corneal haze was lighten and there was no significant difference between the two groups.2. At 1d after mechanical and chemical epithelial deepithelialization PRK, HE stain show that there was "acellular zone" in the prior corneal stroma, the number of keratocyte was decreased more significantly in the chemical groups than in the mechanical groups; at 7d, the keratocytes hyperplasia and transformed into myofibroblasts, the number was increased more significantly in the chemical groups than in the mechanical groups; the number of keratocyte peaked at 30d ; at 90d, the number was decrease and there was no significant difference between the two groups.3. After both mechanical and chemical epithelial deepithelialization PRK, the corneal epithelial and keratocyte were consistently positive for TGF-β1 and bFGF antibody during the corneal wound healing time and in the control group. TGF-β1 and bFGF antibody positivity peaked as the corneal haze peaked and decreased as the wound healing approached completion.4. TGF-B 1 and bFGF mRNA were observed in control group. Both them were decreased at 1d after mechanical and chemical epithelial deepithelialization PRK. They were increased at 7d, and there was siginificant different between the mechanical group and the chemical group(P<0.01). TGF-β1 and bFGF mRNA were peaked as the corneal haze peaked at 30d and there was no siginificant different between the mechanical group and the chemical group(P>0.05). They were decreased as the wound healing approached completion and there was no siginificant different between the two groups.5. The TGF-β1 and bFGF mRNA wae positively correlated with the expression of the keratocyte and correlation coefficients were 0.744(P<0.01), 0.738(P<0.01), 0.664(P<0.01), 0.785(P<0.01).Conclusions:1. The corneal haze was appeared after mechanical and chemical epithelial deepithelialization PRK and peaked at 30d and decreased as the wound healing approached completion. Because of the chemical toxicity, the grade was fewer in the mechanical group than the chemical group at 7d, but there were no significant difference at 30d and 90d.2. After mechanical and chemical epithelial deepithelialization PRK, the keratocyte in the comeal stroma undergo the process of "decrease-active-increase" and the chemical group was more marked. The increase and activation of the keratocyte plays important role in the formation of haze.3. The expression of TGF-β1 and bFGF mRNA pl...
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