Heavy Metal Concentrations in Human Eyes

To measure the concentration of toxic heavy metals in the fluids and tissues of human eyes.

Laboratory investigation.

Thirty autopsy eyes of 16 subjects were dissected to obtain the aqueous, vitreous, lens, ciliary body, retina, and retinal pigment epithelium/choroid. Concentrations of lead, cadmium, mercury, and thallium in ocular tissues, ocular fluids, and blood were determined using an inductively coupled plasma-mass spectrometer and expressed as ng/g. Heavy metal concentrations in ocular tissues were compared using a paired t test.

Lead and cadmium were found in all of the pigmented ocular tissues studied, concentrating to the greatest extent in the retinal pigment epithelium/choroid (mean, 432 ± 485 ng/g and 2,358 ± 1,522 ng/g). Cadmium was found in the retina in all eyes (mean, 1,072 ± 489 ng/g) whereas lead was found in the retina in 9 (30%) of 30 eyes (mean, 53 ± 54 ng/g). Trace concentrations of lead and cadmium were detected in the vitreous (mean, 0.5 ± 1.0 ng/dl and 19 ± 29 ng/dl), lens (mean, 13 ± 18 ng/g and 20 ± 18 ng/g), and blood (mean, 0.5 ± 1.2 μg/dl and 3.1 ± 4.1 μg/l) but were not detected in the aqueous. Mercury and thallium were not detected in any ocular tissues or fluids or in the blood.

Lead and cadmium accumulate in human ocular tissues, particularly in the retinal pigment epithelium and choroid. The potential ocular toxicity of these heavy metals and their possible role in eye disease requires further study.