Abstract
Prevalence data for primary open angle glaucoma (POAG), taken from eight population surveys, was smoothed by curve-fitting to derive composite estimates with respect to quinqennial age groups from 40-44 to 85-89 years. These were applied to national population figures to provide a distribution of cases with respect to age. Estimated prevalence for age 40-89 years in mainly white Caucasian people was 1.2%, rising from 0.2% for those in their 40s to 4.3% for those in their 80s. Of the total cases, 7% were less than 55 years old, 44% were aged 55-74 years, and 49% were older. `Implied incidence' was estimated from the prevalence results, being 0.11% per year in people aged 55 to 74 years. The analysis applied to relatively narrow definitions of POAG. If `probable' cases and also `ocular hypertensives requiring treatment' (of relevance for glaucoma screening) were included, the prevalence would be almost twice as high. Also, a larger proportion of potential cases for a screen would be less than 55 years old, partly because the average age of incident (i.e., newly developed) cases is less than that of prevalent (i.e., all existing) cases.