This review details the current understanding of the mechanism of action and corneal effects of mitomycin C (MMC) for prophylactic prevention of stromal fibrosis after photorefractive keratectomy (PRK), and includes discussion of available information on dosage and exposure time recommended for MMC during PRK. MMC is an alkylating agent, with DNA-crosslinking activity, that inhibits DNA replication and cellular proliferation. It acts as a pro-drug and requires reduction in the tissue to be converted to an active agent capable of DNA alkylation. Although MMC augments the early keratocyte apoptosis wave in the anterior corneal stroma, its most important effect responsible for inhibition of fibrosis in surface ablation procedures such as PRK is via the inhibition of mitosis of myofibroblast precursor cells during the first few weeks after PRK. MMC use is especially useful when treating eyes with higher levels of myopia (≥approximately 6 D), which have shown higher risk of developing fibrosis (also clinically termed late haze). Studies have supported the use of MMC at a concentration of 0.02%, rather than lower doses (such as 0.01% or 0.002%), for optimal reduction of fibrosis after PRK. Exposure times for 0.02% MMC longer than 40 s may be beneficial for moderate to high myopia (≥6D), but shorter exposures times appear to be equally effective for lower levels of myopia. Although MMC treatment may also be beneficial in preventing fibrosis after PRK treatments for hyperopia and astigmatism, more studies are needed. Thus, despite the clinical use of MMC after PRK for nearly twenty years—with limited evidence of harmful effects in the cornea—many decades of experience will be needed to exclude late long-term effects that could be noted after MMC treatment.

本综述详细介绍了目前对丝裂霉素 C (MMC) 预防光屈光性角膜切除术 (PRK) 后间质纤维化的作用机制和角膜效应的理解，并讨论了有关 PRK 期间推荐用于 MMC 的剂量和暴露时间的可用信息。MMC 是一种烷化剂，具有 DNA 交联活性，可抑制 DNA 复制和细胞增殖。它充当前药，需要减少组织才能转化为能够进行 DNA 烷基化的活性剂。尽管 MMC 增强了前角膜基质中的早期角膜细胞凋亡波，但其在 PRK 等表面消融程序中抑制纤维化的最重要作用是通过在 PRK 后的前几周抑制肌成纤维细胞前体细胞的有丝分裂。MMC 的使用在治疗近视度数较高（≥ 约 6 D）的眼睛时特别有用，这些眼睛已表现出较高的纤维化风险（临床上也称为迟发性混浊）。研究支持使用浓度为 0.02% 的 MMC，而不是更低的剂量（例如 0.01% 或 0.002%），以最佳地减少 PRK 后的纤维化。0.02% MMC 的曝光时间超过 40 秒可能对中度至高度近视（≥6D）有益，但较短的曝光时间似乎对低度近视同样有效。尽管 MMC 治疗也可能有益于预防远视和散光 PRK 治疗后的纤维化，但还需要更多的研究。因此，