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Bruce Ira Gaynes, Susanne Tidow-Kebritchi, Cossette Joy, Peter Filip, Laura Burke, Neelam Balasubramanian, Martina Schmeling; In Situ Deposition of Heavy Metals in the Lens of the Human Eye. Invest. Ophthalmol. Vis. Sci. 2016;57(12):6221.
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© ARVO (1962-2015); The Authors (2016-present)
Environmental heavy metal exposure plays a role in many disease processes. However, quantifying cumulative exposure over one's lifetime is exceedingly difficult. Heavy metals are readily adsorbed to tissue protein, thus as lens epithelial cells infoliate with growth the lens may sequester and store xenobiotics over a lifetime. Here, we describe both in qualitative and quantitative terms the content of heavy metals in the crystalline lens at the time of cataract surgery.
Study design was a cross sectional analysis of lens specimens taken at the time of cataract surgery. Following collection, lens samples were centrifuged and the supernatant used as a blank for subsequent spectroscopy by Total Reflection X-Ray Fluorescence (TXRF). Lens tissue and supernatant were subjected to a 1:1 dilution with both water and concentrated high purity nitric acid before being analyzed by TXRF. Relevant data such as concomitant diseases and patient demographics were also collected from electronic records (EPIC).
A total of 84 individuals were enrolled for study, 66% were female. Mean age was 70 yrs, mean body mass index 30.25. Among all subjects 5.2% were current smokers, 46% former smokers. Statistical analysis revealed four common heavy metals in the lens at time of cataract surgery. These included iron (mean=32.68 μg/L range 0-500 μg/L); rubidium (mean=6.71 μg/L, range 0-22.6 μL), zinc (mean=5.43 μg/L, range 0-114 μL) and copper (mean=0.51 μg/L, range 0-19.10 μL). Additional metals found in lens bulk included lead and strontium. Although not statistically significant, zinc appeared to be protective against posterior subcapsular cataract while lens Rb appears to be inversely related to rates of heart failure.
Heavy metals are found in small but measurable quantities in the aged human lens and include forms that are associated with both detrimental and beneficial biologic action. The consequence of rubidium in the human lens is currently unknown however there is evidence of some degree of toxicity of rubidium for humans including neuromuscular hyperirritability. Copper, iron and zinc were found in quantities far below that typical of human serum. Further study is required to define the association between heavy metal deposition in the lens and various forms of ocular and systemic disease as noted by the interesting finding regarding lens Rb and heart failure.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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