Approximately 25 percent of eyes deemed to be normal based on dilated eye examination by a primary eye care ophthalmologist or optometrist had macular characteristics that indicated age-related macular degeneration, according to a study published by JAMA Ophthalmology.
Approximately 14 million Americans have AMD, and age-related macular degeneration is the leading cause of irreversible vision impairment in older adults in the United States, yet little is known about whether AMD is appropriately diagnosed in primary eye care.
David Neely, MD, of the UAB Department of Ophthalmology, and colleagues conducted a study that included 644 people 60 years or older with normal macular health per medical record based on their most recent dilated eye examination by an ophthalmologist or optometrist. Presence of AMD was based on imaging (color fundus photography).
With an average age of 69, 75 percent of the participants had no AMD, in agreement with their medical record while 25 percent had AMD despite no diagnosis of AMD in the medical record. Among eyes with undiagnosed AMD, 78 percent had small deposits (drusen) under the retina, 78 percent had intermediate drusen, and 30 percent had large drusen.
Undiagnosed AMD was associated with older patient age, male sex and a less than high school education. Prevalence of undiagnosed AMD was not different for ophthalmologists and optometrists.
The authors note that the eyes with undiagnosed AMD that had AMD with large drusen would have been treatable with nutritional supplements had it been diagnosed.
"The reasons for AMD underdiagnoses in primary eye care remain unclear," Neely said. "As treatments for the earliest stages of AMD are developed in the coming years, correct identification of AMD in primary eye care will be critical for routing patients to treatment as soon as possible so that the disease can be treated in its earliest phases and central vision loss avoided."
Neely said that detailed fundus examinations for patients are still a good way to be screened for AMD, especially for those paitents with the common risk factors like older age, family history of AMD, hyperopia and others. He said while AMD is not necessarily hard to diagnose, the early forms, which show pigmentary changes and few small drusen, can be very subtle and require a very detailed fundus examination.
"Fortunately, the advanced forms, like exudative or wet AMD, are more readily diagnosed and sent promptly to vitreoretinal subspecialists for intervention," Neely said.