Abstract
Purpose::
To investigate the possibility of cohort effects on prevalence of age-related cataract endpoints.
Methods::
The population in the Beaver Dam Eye Study (n=4926) were examined in 1988-90, 1993-95, 1998-2000, and 2003-05. Standardized photographs of the lens were taken at each examination and graded by protocols. Other information was collected at each examination including a standard medical interview. With multiple visits, we are able to examine birth cohort effects by comparing prevalence rates of similarly aged persons at each exam phase (thus, different birth cohorts).
Results::
The age-specific prevalence of cataract declined in later birth cohorts. For example, among persons 65-69 at each examination, 10.6% (95% confidence interval [CI] 4.9, 16.3) of those born in 1938-42 (seen at the 2003-05 examination) had nuclear cataract, while 16.0% (95% CI 12.6, 19.8) of those born in 1933-37 (seen at 1998-2000 examination) and 27.7% (95% CI 23.5, 30.8) of those born in 1923-27 (seen at 1993-95 examination) had nuclear cataract. Similar cohort differences appear for cortical, posterior subcapsular cataract, and surgery prevalence. In addition, our data suggest cohort effects on incidence.
Conclusions::
Age-related cataract prevalence appears to be influenced by cohort effects such that among similarly aged persons, those in more recent birth cohorts are relatively protected compared to persons born earlier.
Keywords: clinical (human) or epidemiologic studies: biostatistics/epidemiology methodology • cataract • clinical (human) or epidemiologic studies: prevalence/incidence