Paulsen AJ, et al. - Authors ascertained the incidence of and factors related to contrast sensitivity (CS) impairment among middle-aged adults. In the 10-year follow-up, CS impairment was common with cadmium, but not lead, exposure associated with increased risk. The changes in behavior may reduce the future incidence of CS impairment; as demonstrated by the associations of diminished CS with other modifiable risk factors.

Methods

• Experts conducted the Beaver Dam Offspring Study (an ongoing longitudinal cohort study of aging involving adults in Beaver Dam, Wisconsin).
• They included the participants who were free of CS impairment in both eyes at baseline (N=1983).
• From June 8, 2005, through August 4, 2008, baseline data collection occured when the participants ranged from 21 to 84 years of age.
• They conducted 2 follow-up examinations at 5-year intervals: one was conducted between July 12, 2010, and March 21, 2013, and the other between July 1, 2015, and November 13, 2017.
• They performed the data analysis from November 27, 2017, to February 27, 2018.
• They conducted contrast sensitivity testing with Pelli-Robson letter sensitivity charts, and defined incident impairment as a log CS score less than 1.55 in either eye at any follow-up examination.
• In whole blood with inductively coupled plasma mass spectrometry, cadmium and lead levels were measured.
• Experts examined the correlations between baseline characteristics and CS impairment incidence Cox proportional hazard models and quantified as hazard ratios (HRs) with 95% CI.

Results

• Findings suggested that, out of the 1983 participants included, 1028 (51.8%) were female and 955 (48.2%) were male, with a mean (SD) age of 48 (9.3) years.
• Results demonstrated the 10-year cumulative incidence of CS impairment to be 24.8% (95% CI, 22.9-26.8), similar in women (24.9%) and men (24.6%), and highest in the oldest age group (65-84 years) at 66.3%.
• In multivariable models, they noted the association of cadmium level in the highest quintile (HR, 1.35; 95% CI, 1.02-1.78), older age (HR, 1.36; 95% CI, 1.25-1.47), larger waist circumference (HR, 1.06; 95% CI, 1.01-1.11), and more plaque sites (1-3 sites: HR, 1.43; 95% CI, 1.07-1.92; 4-6 sites: HR, 2.75; 95% CI, 1.26-6.05) with increased risk, while male sex (HR, 0.77; 95% CI, 0.60-0.98) and any alcohol consumption (HR, 0.61; 95% CI, 0.43-0.88) were associated with decreased risk.
• Authors noted similar results when cadmium exposure in the models were replaced by smoking status.
• As per data, they noted no association of lead level with increased risk.