AbstractVisual function of an institutionalized population with intellectual disability, consisting of 70 subjects with a mean age of 70.1 (range 60–92) years at initial evaluation, was assessed during a 10‐year prospective longitudinal study. One subject had Down's syndrome and could not be assessed as a result of dementia. Lower visual acuity values were relatively overrepresented as compared to reported data from ageing populations without intellectual disability. In addition, the prevalence of moderate to severe visual impairment was distinctly higher (27.9% in the group studiedvs. 0.66% at age 60–69 years to 13% over age 80 in a population without intellectual disability). During follow‐up, visual function improved in three out of 61 subjeas (4.9%) after cataract surgery, and deteriorated in eight out of 61 subjeas (13.1%), even with optimal correction, as a result of cataract and macular degeneration. Causes of excess impairment were congenital or childhood conditions, too‐late diagnosis of glaucoma and suboptimal correction of refractive errors in non‐cooperative individuals. The present author concludes that it should be possible to reduce excess impairment by an active diagnostic and therapeutic attitude to subjects from a young