Study: Amblyopia almost doubles patients' lifetime risk of bilateral visual impairment

Patients with amblyopia have a nearly two times higher lifetime risk of developing bilateral visual impairment compared with non-amblyopic patients, according to a study by researchers in the Netherlands. Amblyopic patients also live with such impairment an average of 6 months longer than their non-amblyopic counterparts, the authors noted.

Redmer van Leeuwen, MD, and colleagues at Erasmus Medical Center, Rotterdam, investigated the incidence of bilateral visual impairment (BVI) in patients aged 55 years and older who were enrolled in the Rotterdam Study. The researchers used a multistate life-table to determine the lifetime risk of BVI as well as time spent with impairment.

The study enrolled 5,220 patients, of whom 192 (3.7%) had amblyopia.

At 6.5 years mean follow-up, investigators identified 173 patients (3.3%) with incident BVI, according to the study.

Among amblyopic patients, the 5-year cumulative incidence of BVI was 1.4% for those aged 55 to 64 years, 4.8% for those aged 65 to 74 years and 13.3% for those aged 75 to 84 years. Also, these patients had a 2.6 relative risk of BVI, the authors reported.

In the non-amblyopic population, the 5-year cumulative incidence of BVI was 0.3% for those aged 55 to 64 years, 1.2% for those aged 65 to 74 years and 5% for those aged 75 to 84 years.

Based on the life-table analysis, amblyopic patients had an 18% estimated lifetime risk of BVI compared with 10% for non-amblyopic patients. Additionally, amblyopic patients affected by BVI lived an average of 7.2 years with their impairment, compared with 6.7 years for non-amblyopic patients affected by BVI, according to the study.

"This study provides data for future cost-effectiveness analyses," the authors said.

The study is published in the November issue of British Journal of Ophthalmology.