Paulsen AJ, et al. - The incidence and factors associated with contrast sensitivity (CS) impairment were determined by researchers in this longitudinal cohort study of 1983 participants who were free of CS impairment in both eyes at baseline. In the 10-year follow-up, incident CS impairment was common with cadmium, but not lead, exposure related to increased risk. The association of decreased CS with other modifiable risk factors seems to indicate that behavioral changes can reduce the future incidence of CS impairments.

Methods

• Authors conducted the Beaver Dam Offspring Study (an ongoing longitudinal cohort study of aging involving adults in Beaver Dam, Wisconsin).
• From June 8, 2005, through August 4, 2008, baseline data collection occurred when the participants ranged from 21 to 84 years of age.
• Two follow-up examinations were conducted at 5-year intervals: one between July 12, 2010, and March 21, 2013, and the other between July 1, 2015, and November 13, 2017.
• From November 27, 2017, to February 27, 2018, data analysis was performed.
• 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.
• Associations between baseline characteristics and incidence of CS impairment were investigated using Cox proportional hazard models and quantified as hazard ratios (HRs) with 95% CI.

Results

• Findings suggested that, out of the included 1983 participants, 1028 (51.8%) were female and 955 (48.2%) were male, with a mean (SD) age of 48 (9.3) years.
• It was observed that the cumulative 10-year incidence of CS impairment was 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) with decreased risk.
• The results were comparable when cadmium exposure was replaced by smoking status in the models.
• No association was found between lead level and increased risk.