Visual impairment of age-related macular degeneration. An epidemiological study of 1000 aged individuals.

To emphasize the unknown visual impairment of age-related macular degeneration (AMD)-defined as macular changes causing a visual acuity of 6/9 or less-an epidemiological study was designed including 1000 age stratified and randomly selected Danes, 60-80 years of age. Among the 924 individuals in whom both maculae could be examined (1848 eyes) a total number of 173 AMD eyes was found in 112 persons. For all AMD eyes, the composition of visual loss can be described as an iceberg with minor visual impairment of 6/9-6/12 as the predominant base (71.7%), partial impairment of 6/18-6/36 as an interjacent area (15.0%) and major impairment of 6/60 or less (i.e. blindness) as the top (13.3%). By use of a logistric regression model the proportion of exudative macular degeneration among all AMD eyes (atrophic + exudative) was demonstrated to be significantly increasing with decreasing visual acuity but unrelated to age. The prevalence rates of AMD were age related in each of the visual subgroups of minor, partial and major impaired eyes. The prevalence rates of social blindness (6/60 or less in both eyes) due to AMD are estimated to be 4.3 per 1000 persons and of monocular blindness 16.2 per 1000. Further calculations suggest that about 90,000 out of 870,000 Danes. 60-80 years old, have visual impairment of 6/9 or less caused by AMD in one or both eyes.