(一)EFFECTS OF MITOMYCIN C ON RABBIT CORNEA AFTER PHOTOREFRACTIVE KERATECTOMY(二)HISTOCHEMICAL ULTRASTRUCTURE OF MACULAR CORNEAL DYSTROPHY

Haze is one of the Common complications after PRK and PTK and its incidence and severity are closely related to the amount of laser ablation. Although LASLK is more widely used to avoid haze it is still unsolved problem for the patients who need PRK or PTK. Many previous studies have failed to show the morphological basis of haze and therefore there are no effective therapies. The transparency depends on comeal structure which mainly consists of cells, collagen and proteoglycans(PGs). PGs are important to maintain regular collagen fibril arrangement and to control corneal hydration, but it is difficult to visualize PGs and so there are no data about the relationship between haze and PGs and about the effects of anti-metabolic drugs on PG changes in the stroma after PRK. This study investigated PRK rabbit cornea morphologically for the possible role of keatocytes and PGs on haze formation and the effects of mitomycin C. Cellular changes were analyzed by light microscopy and CMTF in vitro and in vivo, respectively. Ultrahistochemical technique-9-(Cuprolinic blue staining) was used for visualize PGs in the corneal stroma. The main results include:1.The comeal surface was fully epithelialized within 4-6 days after PRI( in all the eyes and there was no statistical difference between mitomycin C group and the control (P>0.05).2.The trends of haze change were similar in the both groups but the peak of haze formation was seen 2 weeks earlier in the mitomycin C group, but there was no significant difference between the two groups(P>0.05).3.Light microscopy showed less proliferation of corneal epithelium in mitomycin C group within 4 weeks after PRK but the epithelium was normal in the both groups at 8 weeks. The cell count(CC) of the normal cornea was higher in the anterior stroma, compared with the posterior (P