advertisement
Metals, such as copper, magnesium, zinc, iron, manganese, molybdenum, selenium, and nickel, acting primarily through their activity as enzymatic cofactors, function to control metabolic and signaling functions, making them essential for cellular activity. However, heavy metals (lead, cadmium, mercury and thallium) can be toxic at very low concentrations. The melanin-containing tissues of the eye have high affinity for lead.1 Lead is a neurotoxin that has been linked to visual deterioration,1 cataract formation in men,2 and development of age-related macular degeneration.3 Lead may be an important nonpressure dependent factor contributing to progression of glaucomatous optic neuropathy. Yuki et al. (1756) evaluated the association between hair lead concentration and POAG. They found a higher lead level associated with glaucoma in women, especially in normal-tension glaucoma. Sex-related differences in relation to lead accumulation might be explained by its efflux from bone in women that occurs with age, pregnancy, lactation and menopause.4 The rate of progression of optic nerve damage has been reported to be faster in women than in men with normal-tension glaucoma.5 Lead may induce retinal ganglion cell death by activation of the N-methyl- D-aspartate receptor, leading to Ca2+ influx and excitotoxic damage.6 Higher lead levels in women may be an independent factor for nonpressure dependent progression of glaucomatous optic neuropathy.