The human eye, the highly specialized organ of vision, is greatly influenced by oxidants of endogenous and exogenous origin. Oxidative stress affects all structures of the human eye with special emphasis on the ocular surface, the lens, the retina and its retinal pigment epithelium, which are considered natural barriers of antioxidant protection, contributing to the onset and/or progression of eye diseases. These ocular structures contain a complex antioxidant defense system slightly different along the eye depending on cell tissue. In addition to widely studied enzymatic antioxidants, including superoxide dismutase, glutathione peroxidase, catalase, peroxiredoxins and selenoproteins, inter alia, metallothioneins (MTs) are considered antioxidant proteins of growing interest with further cell-mediated functions. This family of cysteine rich and low molecular mass proteins captures and neutralizes free radicals in a redox-dependent mechanism involving zinc binding and release. The state of the art of MTs, including the isoforms classification, the main functions described to date, the Zn-MT redox cycle as antioxidant defense system, and the antioxidant activity of Zn-MTs in the ocular surface, lens, retina and its retinal pigment epithelium, dependent on the number of occupied zinc-binding sites, will be comprehensively reviewed.

中文翻译：

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人眼中的抗氧化防御：以金属硫蛋白为重点

人眼是高度专业化的视觉器官，受到内源性和外源性氧化剂的极大影响。氧化应激会影响人眼的所有结构，尤其是眼表，晶状体，视网膜及其视网膜色素上皮，这被认为是抗氧化保护的天然屏障，有助于眼睛疾病的发作和/或发展。这些眼部结构包含复杂的抗氧化剂防御系统，视细胞组织而定，沿眼睛方向略有不同。除了被广泛研究的酶促抗氧化剂，包括超氧化物歧化酶，谷胱甘肽过氧化物酶，过氧化氢酶，过氧化氧还蛋白和硒蛋白外，金属硫蛋白（MTs）被认为是具有越来越高的兴趣的抗氧化剂蛋白，其具有进一步的细胞介导功能。这个富含半胱氨酸的低分子蛋白质家族以涉及锌结合和释放的氧化还原依赖性机制捕获并中和自由基。MTs的技术水平，包括同工型分类，迄今为止描述的主要功能，作为抗氧化剂防御系统的Zn-MT氧化还原循环以及Zn-MT在眼表，晶状体，视网膜及其视网膜中的抗氧化活性色素上皮，取决于所占据的锌结合位点的数量，将被全面审查。