Age-Related Macular Degeneration Remains the Number One Cause of Vision Loss
Researchers from the University of Wisconsin School of Medicine and Public Health, examined 20-year trends in visual impairment and associations with age-related eye diseases and socioeconomic factors as found in the Beaver Dam Eye Study. The Beaver Dam Eye Study is funded by the National Eye Institute, one of the 20 National Institutes of Health. The purpose of the Study is to collect information on the prevalence and incidence of age-related cataract, macular degeneration and diabetic retinopathy, which are all common eye diseases causing loss of vision in an aging population.
Age-related macular degeneration is an irreversible destruction of the macula (the central area of the eye's retina), which leads to loss of the sharp, fine-detail, “straight ahead” vision required for activities like reading, driving, recognizing faces, and seeing the world in color, according to the BrightFocus Foundation. As many as 11 million people in the United States have some form of age-related macular degeneration. This number is expected to double to nearly 22 million by 2050.
Little research has been done to track trends in incidence of visual impairment over long periods of time and these details may be important because of an aging U.S. population, "who are most vulnerable to loss of vision resulting from age-related diseases," write the researchers in their introduction.
The study included 4,926 participants, aged 43 to 86 years, in the baseline examination phase from 1988 through 1990, and 3721, 2962, 2375, and 1913 persons participated in follow-up examinations each spaced 5 years apart from 1993 through 1995, 1998 through 2000, 2003 through 2005, and 2008 through 2010, respectively.
Incident of visual impairment (IV) was defined as best-corrected visual acuity of poorer than 20/40 in the better eye in persons with one or both eyes 20/40 or better at the beginning of a 5-year interval, and incidence of severe VI, defined as best-corrected visual acuity of 20/200 or worse in the better eye in persons with one or both eyes better than 20/200 at the beginning of a 5-year interval.
Of 9,548 person-visits, visual impairment developed in 1.4% (95% CI 1.1% to 1.6%) and severe visual impairment developed in 0.4% (95% CI 0.2% to 0.5%) of person-visits. Incidence was associated with age and ranged from 01. %
More among patients ages 50 to 54 to 14.6% among patients age 85 and older.
No statistically significant interactions were found between time span and age or in visual impairment between time spans, except with a comparison of periods 1 and 2 with periods 4 and 5, when incidence dropped by nearly half.
Overall incidence of severe visual impairment was associated with age, no visual impairments were reported among participants aged 50 to 54 and 60 to 64 years , in comparison to 0.2% of patients ages 70 to 74, 1.6% of patients ages 80 to 84, and 6.9% of patients ages 85 and older.
In their conclusion the researchers write” These data provide population-based estimates that show a high (15%) 5-year incidence of VI in persons 85 years of age and older. Age-related macular degeneration remained the leading cause of severe VI in this population over the 20 years of the study.”
According to Dr. Ronald Klein, MD, MPH, University of Wisconsin School of Medicine and Public Health, Department of Ophthalmology and Visual Sciences, late age-related macular degeneration was the primary cause in 44% of eyes, followed by branch or central retinal vein occlusion in 8% and cataract in 10%.
This study appears in the journal Ophthalmology.