AMD leading cause of bilateral vision loss among Icelandic adults

Acta Ophthalmol. 2008;86(7):778-785.

Age-related macular degeneration was the leading cause of bilateral visual impairment and blindness in a study of adults age 50 years and older in Iceland. AMD accounted for more than half of all cases of visual impairment, and the rate of geographic atrophy was double that of exudative or wet AMD.

The most common causes of unilateral visual loss were amblyopia, cataract and glaucoma. The prevalence of visual loss increased with age, the study authors said.

The Reykjavik Eye Study included 1,045 subjects age 50 years and older. Study criteria were World Health Organization definitions of bilateral visual impairment (best corrected visual acuity worse than 6/18 or visual field between 5° and 10° around the fixation point in the better eye) and blindness (visual acuity worse than 3/60 or visual field less than 5° in the better eye).

Criteria also included U.S. definitions of bilateral visual impairment (visual acuity worse than 6/12) and blindness (visual acuity of 6/60 or worse) in the better eye.

Data based on WHO criteria showed a 0.96% prevalence of bilateral visual impairment and a 0.57% prevalence of blindness. Based on U.S. criteria, data showed a 2.01% prevalence of bilateral visual impairment and a 0.77% prevalence of blindness.

The rates of unilateral visual impairment were 4.4% with WHO criteria and 5.45% with U.S. criteria. The rates of unilateral blindness were 1.72% with WHO criteria and 3.06% with U.S. criteria.

These findings indicate that Iceland’s rate of exudative vs. geographic atrophy AMD is higher than the U.S. rate, which may reflect the fact that the population is Nordic; Caucasians with blue eyes are at higher risk for AMD in general. Early detection and prompt treatment, especially for the exudative form, which can come on suddenly and progress rapidly, are critical to preserving vision.

Early detection is also critical for reducing the prevalence of amblyopia, the most common cause of unilateral vision loss reported. Amblyopia, if treated in early childhood, is preventable.

Both findings speak to the importance of prevention — early screenings and intervention — for maintaining eye health, especially for those at greater risk of these high-incidence culprits. Equally crucial are rehabilitation services, which restore functioning and reduce the disabling consequences of irreversible vision loss.

We need more random studies of populations by country like this one, as well as comparative views of eye problems by country, to better take aim at the vision loss epidemic.

– Tara A. Cortes, PhD, RN
Lighthouse International