Refractive Errors and Visual Acuity in a Danish Subpopulation. The INTER99 Eye Study

Abstract

Abstract: : Purpose: The present study describes baseline findings of refractive errors and visual acuity in the prospective population-based Inter99 Eye Study. Methods: The study comprised 970 subjects aged 30 to 60 years: 47.8 (7.7) years (mean (SD)). All subjects answered a detailed questionnaire and underwent a standardized general physical and ophthalmic examination including subjective refractioning and determination of best corrected visual acuity. Results: A total of 0.5% of the study population was blind in one eye (VA ≤ 0.05) and 2.2% had low vision in one eye (VA ≤ 0.3). The main cause of impaired visual function was strabismic amblyopia (1.8% of the study population). Myopia (≤ -0.5 D spherical equivalents) in right eyes was present in 33.2% of subjects. Myopia in right eyes was significantly more prevalent in subjects with a university degree university degree (59.2% versus the average of 31.1% in subjects without a university degree, p<0.0001, Χ²-test), but no overall association was found between myopia and educational level. Conclusions: Visual impairment was mainly due to strabismic amblyopia whereas no cases of visual impairment due to age-related diseases were found. The prevalence of amblyopic visual impairment is thus higher than that reported in Swedish children (0.25%), but comparable to that reported in an adult Australian population (3.1%). The high prevalence of myopia in subjects with a university degree in the present and other studies may potentially be caused by coinheritance of intelligence and myopia susceptibility genes. These genes would hypothetically be activated only when sustained near work is performed.

Keywords: amblyopia • myopia • clinical (human) or epidemiologic studies: hea