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Laura Burke, Martina Schmeling, Susanne Tidow-Kebritchi, Peter Filip, Nicholas Elliot, Jeffrey Gaynes, Bruce Ira Gaynes; In situ heavy metal concentrations in human aqueous humor and lens.. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):5719.
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© ARVO (1962-2015); The Authors (2016-present)
Heavy metals are ubiquitous elements that can accumulate in human tissue from various sources including inhalation and ingestion of contaminated water supplies. Limited data exists regarding the in-situ concentration of heavy metals in ocular fluids and tissues of humans. It is unclear if heavy metals in ocular fluid such as aqueous humor accumulate in sufficient quantity so as to impact cellular function. This study aims to provide a descriptive analysis of heavy metals found in aliquots of aqueous humor and homogenized lens tissue obtained during cataract surgery.
Samples of aqueous humor and fragmented lenses were obtained during cataract extraction of human subjects (N=11). Each sample was diluted 1:1 with ultrapure water, dried at 60C, and analyzed with total reflection X-ray fluorescence (TXRF) for heavy metal content. Concentrations were measured a minimum of 2 times per sample for accuracy. Data was corrected for heavy metal contaminants in balanced saline solution (BSS) used intra-operatively.
Within extracted lens material, the most commonly found heavy metals were chromium and manganese (90.9% of patients), followed by barium and cerium (63.6% each). The highest average concentration of a heavy metal was cerium (86.7 μg/L), followed by iron (80.4 μg/L), and barium (47.6 μg/L). Lead was found in four samples, with an average of 1.8 μg/L within those samples. Within aqueous humor, the most commonly found heavy metals were bromine and chromium (each found in 90.9% of patients), followed by copper (72.7%), iron and zinc (54.5% each). The highest average concentration was bromium (2,275.9 μg/L), followed by chromium (119.8 μg/L), and copper (105.3 μg/L). Lead was found in four samples, with an average of 2.4 μg/L within those samples.
Our results demonstrate that heavy metals are found in both human aqueous humor and lens tissue in vivo. Most common and highest average concentration of heavy metals vary extensively between aqueous humor and lens samples. Interestingly, one of the most commonly found heavy metals with in the lens (manganese), was not found in any samples of aqueous humor. Also of note, chromium and/or lead were found in ocular fluid and/or lens material of all patients, and are known to induce marked tissue necrosis and cellular injury. Further studies are needed to analyze the role that these heavy metals may play in ocular physiology and pathology.
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