OBJECTIVE The present study was performed as part of an epidemiological study, the Inter99 Eye Study. The aim of the study was to describe refractive errors and visual acuity (VA) in a suburban Danish population. METHODS The Inter99 Eye Study comprised 970 subjects aged 30-60 years and included a random control group as well as groups at high risk for ischaemic heart disease and diabetes mellitus. The present study presents VAs and refractive data from the control group (n = 502). All subjects completed a detailed questionnaire and underwent a standardized general physical and ophthalmic examination including determination of best corrected VA and subjective refractioning. RESULTS Visual acuity </= 0.05 was found in one eye of one subject and VA </= 0.3 in 11 eyes of 11 subjects. The main cause of reduced visual function was strabismic amblyopia. Myopia (</= - 0.5 D, spherical equivalent refraction) was present in 33.1% of right eyes of the total population but in 56.8% of subjects with a university degree. CONCLUSIONS Strabismic amblyopia was a significant cause of unilateral visual impairment. Myopia was approximately twice as frequent in subjects with a university degree as in the remaining study population.