Age-Related Visual Impairments May Be Correctable

Neil Osterweil

April 09, 2013

Long-term follow-up data confirm that age-related macular degeneration (AMD) is the leading cause of visual impairment among older adults in the United States, but many older adults have the potential to see better than they currently do, say investigators in the venerable population-based Beaver Dam Eye Study.

In the long-term cohort study, the overall incidence of visual impairment over the course of 5 years was 1.4%, increasing in a linear fashion from 0.1% among 50- to 54-year-olds to 14.6% among those aged 85 years and older, report Ronald Klein, MD, MPH, from the Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, Madison, and colleagues.

"There were significant age-period effects explained, in part, by AMD. This has important public health care implications in estimating the projected burden of the number of those in the United States population expected to become visually impaired. Continued national epidemiologic surveillance is needed to monitor changes in the incidence and prevalence of [visual impairment] and the diseases that cause them to estimate the costs and benefits of new ophthalmologic interventions after they are introduced," the authors write in an article published online March 4 in Ophthalmology.

The data also hint, however, at improvements in the prevention, detection, and treatment of AMD during the study period. The authors note that there was a slight but significant decrease in the odds ratio (OR) for incident visual impairment between the first and final 5-year periods in the study (OR, 0.53; 95% confidence interval [CI], 0.32 - 0.87; P = .01).

"Although this was no longer statistically significant after adjustment for AMD, it still suggests lower rates of incidence in the last 5 years of the study. This may be in part the result of new treatment interventions for AMD," the authors write.

"This suggests that there is something happening with AMD, but we can only infer that there is improvement in detection of AMD or in its management; we don't have any data in the study itself to show that to be the reason," Dr. Klein said in an interview with Medscape Medical News.

The investigators also found that 38% of the visual impairment seen in all eyes in the study was correctable with new refraction, noted David Wu, MD, a vitreoretinal surgeon at Massachusetts Eye and Ear and an instructor in ophthalmology at Harvard Medical School, both in Boston.

"I do think the percentage — 38% improved better than 20/40 and 26% improved at least 1 line but [were] still impaired — speaks to the concept that we as ophthalmologists like to drive home, which is that there is a significant number of people in this age group which may experience visual improvement from ophthalmological evaluation/treatment (even from more general things like refraction, cataract surgery, before getting into more specialized things like treatment of AMD), and they should seek eye care rather than just assuming their eyes are irreversibly getting old," Dr. Wu told Medscape Medical News. He was not involved in the study.

Dr. Klein noted that correction is especially important for older persons: "Visual impairment is associated with higher risk of falls and fractures, for example. Correction reduces the risk," he said.

Eyes on Wisconsin

Since the late 1980s, investigators in the Beaver Dam Eye Study have been tracking and reporting on eye health and visual changes among a large cohort of residents of the bucolic hamlet of Beaver Dam, Wisconsin, located 41 miles northeast of Madison. A total of 4926 predominantly white participants from the ages of 43 through 86 years were enrolled and examined at baseline from 1988 through 1990.

The participants were evaluated with standardized interviews and examination at each vision. Exams included refractions, photographs of the ocular fundus and lens, slit-lamp photographs, and grading of AMD, if present.

In the current study, the authors examined incidence data from follow-up exams conducted every 5 years from 1993 through 1995 (3721 participants), 1998 through 2000 (2962 participants), 2003 through 2005 (2375 participants), and 2008 through 2010 (1913 participants).

They defined visual impairment as a best corrected visual acuity (BCVA) worse than 20/40 in the better eye in participants who had a BCVA in 1 or both eyes of 20/40 or better at the start of a 5-year interval. Severe visual impairment was defined as BCVA 20/200 or worse in the better eye in people who had at least 1 eye better than 20/200 at the start of a 5-year interval.

The overall incidence of severe visual impairment was 0.4%, ranging from 0% in 50- to 54-year-olds to 6.9% in those 85 years of age and older. Of the 440 eyes with severe visual impairment in the study (184 at baselines plus 256 incident cases), 43.9% had late AMD as the primary cause of impairment, 8.0% had branch vein or central retinal vein occlusion, and 10.2% had cataracts. Other cause included trauma (8.4%) macular hole (3.9%), diabetic retinopathy (2.7%), and retinal detachment (3.2%).

The Beaver Dam Eye Study is supported by the National Institutes of Health and Research to Prevent Blindness. Dr. Klein is a principal investigators and grant recipient. The other authors and Dr. Wu have disclosed no relevant financial relationships.

Ophthalmology. Published online March 4, 2013. Abstract