Zinc in the eye.

Zinc has long been recognized as an essential constituent of various tissues. Many clinical conditions and dietary factors reduce the absorption or the biological availability of zinc, and lead to zinc deficiency which produces structural and functional alterations in many organ systems. The highest concentration of this trace element in the human body is measured in the eye, particularly in the pigment-containing components. The deficiency of zinc has a dramatic effect on ocular development especially when it occurs during early prenatal period. Zinc is required for the structure and activity of many ocular metalloenzymes. Although the exact mechanism of its molecular and cellular functions are largely unknown the essentiality of this element in the component of the eye, including the retina, choroid, cornea and lens, is well established; it is also well known that zinc deficiency causes functional impairments in various parts of the eye. Zinc related toxicities have been shown in human and animal eyes.