Background: The distribution of visual impairment is an indicator of the health status of the population and for the frequency of diseases of the eye.
Methods: The Gutenberg Health Study (GHS) is a population-based cohort study in Germany concerning adults aged 35 to 74. 15 010 subjects from the Mainz-Bingen region underwent general medical and ophthalmological examination, with measurement of the distance-corrected visual acuity in each eye separately. As per the World Health Organization criteria, visual impairment was defined as an acuity below 0.3 in the better eye, and blindness as an acuity below 0.05. All patients who were found to be visually impaired or blind underwent further individual study with clinical history-taking, split-lamp examination, and fundus photography.
Results: Data from 14 687 subjects were evaluated. The mean age of the partici- pants was 55.0 years (standard deviation, 11.1 years). The prevalence of visual im- pairment was 0.37% (95% confidence interval [0.28; 0.49]) (n = 55) and was higher in women (0.44%) than in men (0.31%). Blindness was present in 0.05% [0.03; 0.11] (n = 8) of the subjects. The prevalence of visual impairment from age 65 on- ward was 0.79%, three times higher than in the younger age groups. 54.5% of the visually impaired subjects had multiple underlying ophthalmological pathologies.
Conclusion: The causes of visual impairment are manifold. Loss of vision is often the combined effect of multiple pathological factors. The etiology of visual impair- ment is thus a more complex matter than is commonly assumed.