Age-related macular degeneration (AMD) is an eye condition that typically occurs in people over the age of 50, and happens when the part of the eye that is used for central vision begins to break down.
A recent study found that, over a 10-year study period, about two thirds of patients who did not have a more advanced form of AMD at the beginning of the study progressed to a more advanced form of AMD within 10 years.
The study's authors noted that there is progressive vision loss with advanced AMD, so it is critical that patients take measures to protect their vision.
"Have your eyes checked regularly."
This study was led by Emily Chew, MD, of the Division of Epidemiology and Clinical Applications at the National Eye Institute under the National Institutes of Health. This research team examined the progression of age-related macular degeneration in a group of older adults over a 10-year study period.
Dr. Chew and colleagues analyzed data from 4,757 participants with AMD between the ages of 55 and 80 in the Age-Related Eye Disease Study. To be included in the study, participants could only have AMD in one eye and had to have a corrected vision of at least 20/32. As a reference, 20/20 vision is considered perfect and a vision of 20/40 or better is required to drive.
Participants received eye exams at the beginning of the study in 1992 and periodically throughout the study until 2001. Images of the eye, specifically the macula (located in the center of the retina), were taken at the beginning of the study and every year for two years after the study began.
The researchers looked at progression to two different forms of advanced AMD which resulted in vision loss for patients. These researchers also looked at total reduction in visual acuity (clearness of vision) by asking patients to identify letters on a chart.
Progression to advanced AMD was based on reports from treatment centers and specific therapies patients received.
Several factors were taken into account that could have influenced AMD progression. These factors included age, race, sex, education level, smoking history, body mass index (a measure of height and weight), medications used and history of diabetes, hypertension, angina and arthritis.
The researchers found that in patients who did not have advanced AMD at the beginning of the study and did not have retinal detachment (where the retina separates from the rest of the eye), about 36 percent had developed advanced AMD 10 years later.
For patients who did not have advanced AMD at the beginning of the study but were experiencing symptoms of retinal detachment, about two thirds developed advanced AMD 10 years later.
The researchers also looked at drusen and its connection to AMD progression. Drusen are yellow deposits found under the retina. Having large drusen is one sign of AMD.
These researchers found that about 71 percent of patients with medium drusen at the beginning of the study progressed to large drusen within 10 years, and about 14 percent of patients with medium drusen developed one of the advanced forms of AMD.
The authors of this study noted that for people who develop a more advanced form of AMD, vision loss is persistent. Consequently, these authors concluded that it is important to be aware of the risk factors for advanced AMD, like age and severity of drusen, so that preventive measures can be taken.
This study was published on January 2 in JAMA Ophthalmology.
The study authors reported no competing interests.