Five-year incidence of visual impairment and blindness in older Icelanders: the Reykjavik Eye Study

Purpose: This study examined age, sex and cause-specific 5-year incidence of visual impairment and blindness in a middle-aged and elderly Icelandic population. Methods: The study cohort consisted of a population-based, random sample of citizens aged >= 50 years. Of 1379 eligible subjects, 1045 underwent a baseline examination in 1996; 846 of the 958 survivors (88.2%) underwent a 5-year follow-up examination in 2001. All participants underwent an extensive ophthalmological examination including best corrected visual acuity (BCVA) using a Snellen chart. We used World Health Organization (WHO) criteria, which define visual impairment as BCVA in the better eye of < 6/18 and >= 3/60 and blindness as BCVA in the better eye of < 3/60. We also used US criteria, which consider BCVA of < 6/12 and > 6/60 in the better eye to represent visual impairment and BCVA of < 6/60 in the better eye to represent blindness. The causes of incident visual loss in either eye were determined. Deterioration or improvement in vision were defined as a loss or gain of >= 2 Snellen lines. Results: According to WHO criteria, 5-year incidence of bilateral visual impairment and blindness were 1.07% (95% confidence interval [CI] 0.37-1.76) and 0.35% (95% CI 0.00-0.76), respectively. Using US criteria, equivalent incidence of bilateral visual impairment and blindness were 3.49% (95% CI 2.24-4.74) and 0.95% (95% CI 0.29-1.60), respectively. Age-related macular degeneration and cataract were the major causes of incident visual impairment and blindness. Conclusions: Incidences of visual impairment and blindness increased significantly with age. Age-related macular degeneration, present in 75% of affected persons, was the most common cause of 5-year incident legal blindness in this middle-aged and elderly Icelandic population.