Heavy metal concentrations in human eyes

Area of Science:

• Ocular toxicology
• Environmental health
• Analytical chemistry

Background:

• Heavy metals are known environmental toxins.
• Understanding their distribution in human tissues is crucial for assessing health risks.
• Ocular tissues may be exposed to systemically absorbed heavy metals.

Purpose of the Study:

• To quantify the concentrations of lead, cadmium, mercury, and thallium in various human ocular tissues and fluids.
• To compare heavy metal levels in ocular tissues with blood concentrations.

Main Methods:

• Laboratory investigation of 30 autopsy eyes from 16 subjects.
• Dissection of ocular tissues: aqueous humor, vitreous humor, lens, ciliary body, retina, and retinal pigment epithelium/choroid.
• Inductively coupled plasma-mass spectrometry (ICP-MS) used to measure metal concentrations (ng/g) in tissues, fluids, and blood.

Main Results:

• Lead and cadmium were detected in all pigmented ocular tissues, with highest concentrations in the retinal pigment epithelium/choroid.
• Cadmium was present in all retinas; lead was found in 30% of retinas.
• Trace levels of lead and cadmium were found in vitreous and lens; none were detected in aqueous humor. Mercury and thallium were not detected in any ocular samples or blood.

Conclusions:

• Lead and cadmium significantly accumulate in human ocular tissues, particularly the retinal pigment epithelium and choroid.
• The presence of these metals suggests potential ocular toxicity.
• Further investigation is warranted to determine the role of lead and cadmium in the pathogenesis of eye diseases.