Objective: To study the prevalence and causes of blindness and visual impairment in various age categories of a large population-based study.
Methods: For the study, 6775 subjects aged 55 years or older underwent an extensive ophthalmologic screening examination, including measurements of visual acuity and the visual field and fundus photography. The causes of blindness or visual impairment were determined using all screening information and medical records.
Results: The prevalence of blindness, according to World Health Organization criteria, ranged from 0.1% in subjects aged 55 to 64 years to 3.9% in subjects aged 85 years or older; the prevalence of visual impairment ranged from 0.1% to 11.8%. For persons younger than 75 years, myopic degeneration and optic neuropathy were the most important causes of impaired vision. For persons aged 75 years or older, age-related macular degeneration was the major cause of the increased prevalence of blindness, whereas age-related cataract predominantly caused the increased prevalence of visual impairment.
Conclusions: The hierarchy of causes of blindness and visual impairment is highly determined by age. As yet, little can be done to reduce the exponential increase of blindness; however, adequate implementation of surgery to treat cataract could reduce visual impairment by one third. Underuse of ophthalmologic care is a prominent cause of the high frequency of untreated cataracts among the elderly.