Prophylactic and therapeutic effects of topical mitomycin C on corneal haze of rabbits submitted to photorefractive keratectomy / Efeitos do uso tópico da mitomicina C na prevenção e tratamento da opacidade corneana em coelhos submetidos à ceratectomia fotorrefrativa

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Purpose: To determine cellular effects and the mechanism through which topical mitomycin C prevents and treats corneal haze after photorefractive keratectomy (PRK) in rabbits. Methods: Minus nine diopters PRK with mitomycin C or balanced salt solution was performed in two hundred and twenty four New Zealand rabbits. Haze level was graded at the slit lamp. Rabbits were sacrificed at 4 hours, 24 hours, 4 weeks or 6 months after surgery and immunohistochemistry was performed with TUNEL assay, Ki67 and alpha-SMA to analyze keratocyte cells apoptosis, keratocyte cells replication and myofibroblast cells formation, respectively. Results: TUNEL-positive cells increased in all mitomycin C groups (representing more keratocyte cells undergoing apoptosis) while Ki67-positive cells decreased significanlty (representing a decreased keratocyte cells replication) following mitomycin C application. A greater decrease in myofibroblasts was noted with prophylactic mitomycin C treatment than therapeutic mitomycin C treatment. There was, however, an anterior stromal acellular zone in eyes treated with mitomycin C that persisted out to the maximum follow-up of 6 months. Conclusion: Mitomycin C application significantly reduced corneal haze formation in rabbits. Its treatment induces apoptosis of keratocytes and myofibroblasts, but the predominate effect in inhibiting or treating haze appears to be at the level of blocked replication of keratocytes or other progenitor cells of myofibroblasts. Treatment with 0.002% mitomycin C appears to be just as effective as higher concentrations (0.02%) in the rabbit model. However, a persistent decrease in keratocyte cells density in the anterior stroma could be a warning sign for future complications

ASSUNTO(S)

córnea opacidade lasik haze mitomicina prk mitomycin cornea lasik prk

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