Nutritional effects of zinc on ocular and systemic physiology.

Zinc, an essential mineral in human nutrition, has multiple and complex ocular and systemic functions. Zinc deficiency is characterized by growth retardation, reduced appetite, skin changes, impaired reproductive development, impaired taste acuity, and impaired wound healing. Zinc deficiency may also cause or contribute to learning problems. Observations of Denver children have suggested that suboptimum zinc nutriture may be quite common in otherwise normal infants and children in the United States. The most likely cause of this deficiency is dietary insufficiency. High concentrations of zinc are found in human ocular tissues and are closely related to visual function. When zinc levels are inappropriately low, results can include ocular birth defects, reduced ability to dark adapt, excessively low IOP, and optic neuritis. Correction of zinc deficiency with zinc supplementation must be done cautiously because excessive zinc can interfere with the metabolism of copper and zinc.