Abstract
Purpose :
To determine if blood cadmium (Cd) and lead (Pb) levels were associated with contrast sensitivity impairment (CSI) in the Beaver Dam Offspring Study (BOSS). Cd and Pb are known to cause neural damage and have been shown to be associated with other sensory impairments and disorders.
Methods :
The BOSS (2005-2008; N=3296) is a cohort study of aging in the adult offspring of the population-based Epidemiology of Hearing Loss Study cohort. Using Pelli-Robson contrast sensitivity charts, CSI was defined as <1.55 log triplets correct in the better eye. Cd and Pb were measured in stored whole blood samples. Associations between Cd, Pb, and CSI were analyzed using logistic regression. Levels of Cd and Pb were analyzed by quintile to compare the highest quintile (Q5, ≥0.53 μg/L and ≥2.07μg/dL, for Cd and Pb respectively) to all others and by doubling of exposure.
Results :
The mean age of participants was 49 years (n=2209) and 7.5% had CSI. In multivariable models Cd was not significantly associated with CSI (for Q5 versus all others OR=1.16, 95% CI=0.71, 1.89; for doubling of Cd level OR=1.09, 95%CI=0.93, 1.29). However, in a sensitivity analysis excluding those with any age-related macular degeneration (AMD) or diabetic retinopathy (DR) based on graded fundus photographs, any cataract based on graded lens images, or measured impaired visual acuity (VA), a doubling of Cd level was associated with increased odds of CSI (OR=1.24, 95% CI=1.02, 1.52). In similar models, there were no significant associations between Pb and CSI (for Q5 versus all others OR=1.06, 95% CI=0.69, 1.64; for doubling of Pb level OR=1.07, 95% CI=0.84, 1.35).
Conclusions :
In these preliminary analyses, no cross-sectional association was found between blood Cd level and CSI in the entire BOSS population at baseline. However, an association was found in those without AMD, DR, cataract, or impaired VA. This observed effect of cadmium may be due to neural changes or deficits caused by the neurotoxin that are masked when those with other eye conditions related to CSI are included in the analysis. No cross-sectional association between blood Pb level and CSI was found in the BOSS cohort at baseline. Further study is needed to understand the relationship between these heavy metals and CSI, including studies on incidence.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.