The prevalence of age-related maculopathy (ARM) in an urban Norwegian population:: the Oslo Macular Study

Purpose: To examine the prevalence of early and late age-related maculopathy (ARM) in citizens aged 51 years and older in the city of Oslo and its surroundings. Methods: We selected a random sample of 800 subjects, using a cross-sectional study design. A total of 459 of the 770 eligible subjects agreed to participate, giving an attendance rate of 59.6%. Stereoscopic colour digital photographs were obtained and graded at a certified reading centre using the International Classification Grading System for ARM. Results: Early ARM in either eye was found in 43.1% (95% CI 38.5-47.7) of subjects aged 51 years and older. This was due to a much higher prevalence of pigmentary changes, predominantly hyperpigmentation in all age groups, than previously reported; 37.5% of people aged 51-60 years of age had pigmentary changes >= 63 mu m, increasing to 66.0% in the oldest age group. In people aged 71 years and older, geographic atrophy (GA) was found in either eye in 3.6% (95% CI 0.4-6.8) and exudative macular degeneration (AMD) was found in either eye in 2.9% (95% CI 0.0-5.7) of subjects. Conclusion: To our knowledge, this is the first published study to rely solely on digital photography for grading purposes in a population-based study. Early ARM was found to have a higher prevalence than previously reported in other populations. Exudative AMD and GA had similar prevalences to those described in the literature, although the prevalence of GA tended to be higher than previously reported in some surveys.