One in 25 US adults with diabetes aged 40 or older has diabetic macular edema (DME), according to a new study sponsored by Genentech/Roche and published online August 14, 2014 in JAMA Ophthalmology.
The research also found that African Americans and 2 other groups are at even higher risk for DME.
"We found that diabetic macular edema is almost 3 times as common in African Americans as in non-Hispanic whites, with Hispanics in between," commented first author Rohit Varma, MD, MPH, director of the University of Southern California (USC) Eye Institute and professor of ophthalmology and preventive medicine at USC Keck School of Medicine. "In addition, we found that those individuals who have diabetes for 10 years or more or who have uncontrolled blood sugars are more likely to have this condition.
"The surprising thing for me was how much higher the risk was in African Americans compared with others," Dr. Varma stated. "We did not know that before. I think this should put a greater focus on African Americans who have diabetes so that they can be screened, evaluated early, and treated."
Indeed, all patients with diabetes should have regular eye exams, he stressed, but this is currently not happening, with many of those with diabetes not even aware that the disease can affect their vision.
DME: A Leading Cause of Vision Loss in Diabetes
Diabetic macular edema affects the retina, which swells with fluid and proteins. DME is one of the leading causes of vision loss in persons with diabetes in the US, according to Dr. Varma.
Screening with eye exams can aid earlier diagnosis and treatment. But even when diagnosed at later stages, DME remains treatable, with vision loss reversible in some people. Educating healthcare providers and patients about the importance of eye screening is crucial.
National guidelines have long recommended regular eye exams for patients with diabetes, but such advice does not always trickle down to the front line of care.
"It's one thing to have guidelines, it's another thing to make sure that they are carried out," Dr. Varma said. "If they're not implemented, we're really not going to benefit from [them]."
A prior analysis suggested that less than half of people with DME had ever been told about the link between their diabetes and vision loss. And only 60% had seen an eye-care provider in the past year (JAMA Ophthalmol. 2014;132: 168-173).
The group of scientists who conducted the new study come from USC, the Wilmer Eye Institute at Johns Hopkins University, Outcomes Insights, Ohio State University, and Genentech.
They drew data from the National Health and Nutrition Examination Survey (NHANES), conducting a cross-sectional analysis of 1038 participants aged 40 and older who had diabetes and fundus photographs from 2005 to 2008.
They determined presence of diabetes based on self-report, HbA1c levels, and/or current medication for diabetes. Masked graders at the University of Wisconsin read the fundus photos and made DME diagnoses based on the NHANES digital grading protocol.
Results revealed a DME prevalence of 3.8%, suggesting that about 746,000 US adults aged 40 or over had DME in 2010.
The likelihood of having DME was greater among non-Hispanic blacks than non-Hispanic whites (odds ratio [OR], 2.64; P = .02), those with higher HbA1c levels (OR, 1.47 for each 1% increase in HbA1c; P < .001), and those with diabetes of 10 years duration or more, compared with those with diabetes for less than 10 years (OR, 8.51; P < .001).
Critically Important to Begin Mass Screening of Eyes in Diabetes
"It is critically important that we find ways of screening people with diabetes for eye disease," Dr. Varma emphasized, "We need to begin a mass campaign so people can get pictures of their eyes done and know in a very short time whether they need treatment."
Just as cuffs for free blood-pressure checks have become commonplace in many supermarkets and pharmacies, Dr. Varma believes eye screening should become similarly accessible.
Optical coherence tomography (OCT) can photograph the eyes as part of the screening process. Less expensive instruments are being developed and could be placed in pharmacies and grocery stories, he says.
"We are failing at this as a society both nationally and worldwide. We do not have adequate education for people who have diabetes with regard to the fact that their eyes can be affected and that they can lose vision from it," Dr. Varma concluded.
"We now have very good treatment modalities that can reverse this vision loss and improve people's vision. Screening much more often would certainly be beneficial."
Dr. Varma has consulted for and/or received research support from Allergan , Aquesys, Genentech, Merck, and Replenish. He also has a grant from Research to Prevent Blindness. Disclosures for the coauthors are listed in the article.
JAMA Ophthalmol. Published online Aug. 14, 2014. Abstract
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Cite this: Diabetic Vision Loss: Screening Key, Blacks at Greatest Risk - Medscape - Aug 15, 2014.
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