Epidemiology of Exfoliation Syndrome

BACKGROUND: From a historical standpoint the epidemiology of exfoliation syndrome (XFS) is one of the most controversial subjects in ophthalmic literature. Current literature abounds with studies on the prevalence of XFS in various ethnic populations and clearly XFS is a common condition, but its true prevalence is difficult to ascertain. Overall, XFS is considered to be the most common identifiable cause of glaucoma worldwide. PURPOSE: This review critically examines the published literature documenting the epidemiological features of XFS and attempts to provide a unified concept concerning existing controversy. METHODS: A critical review of selected literature pertaining to the epidemiology of XFS. RESULTS: It is well established that XFS and the ensuing exfoliative glaucoma have a worldwide prevalence and a progressively increasing age-related incidence. The prevalence of the condition is significantly underestimated. Many past studies have proposed clear geographic variations within and between ethnic groups. In contrast, there has also been some epidemiological evidence suggesting that the prevalence of XFS is similar within various ethnic groups. Published literature fails to address the potential role and impact of suspected exfoliation cases in the reported prevalence figures of the condition. Incidence figures for the condition are limited and vary extensively. Cumulative data have indicated that several, as yet partly understood genetic, ethnic, and environmental factors contribute to the varied prevalence of this condition. CONCLUSIONS: Further understanding on XFS epidemiology is needed. Only a future large prospective study conducted by the same investigators, using similar methodologies for different ethnic populations will prove beyond doubt the hypothesis that significant geographic variations exist. Since patients with exfoliative glaucoma are at significant risk of losing vision it is vital to elucidate the causes and the risk of developing XFS. To reach this goal, it is important to better delineate the early changes of XFS and to focus research efforts on modifiable factors for XFS development.