December 12, 2012
Increase In Vision Impairment Associated With Higher Prevalence Of Diabetes
Lawrence LeBlond for redOrbit.com - Your Universe Online
Vision loss that has been associated with diabetes has been on the incline in the US, with a 20 percent increase seen in less than 10 years. As prevalence of diabetes is also on the rise, and is now being seen more and more in younger people, health experts are worried that a growing number of people are going to suffer from vision problems–notably nonrefractive vision impairment (NVI).
Publishing the results of a new study in the December 12 issue of the Journal of the American Medical Association (JAMA), David Friedman, from the Wilmer Eye Institute of Johns Hopkins University School of Medicine, said the findings are dramatic, “and they're kind of the tip of the iceberg of what's coming ahead.”
Nonrefractive vision impairment (NVI), which includes glaucoma and cataracts, cannot be corrected with glasses, and typically requires laser therapy or surgery. In some cases the condition can lead to permanent vision loss, especially if the problem is not identified and treated early on.
“It is estimated that more than 14 million individuals in the United States aged 12 years and older are visually impaired (<20/40). Of these cases, 11 million are attributable to refractive error. In the United States, the most common causes of nonrefractive visual impairment are age-related macular degeneration, cataract, diabetic retinopathy, glaucoma, and other retinal disorders," according to background information in the article.
Previous studies have shown that visual impairment is common in persons with diabetes. And as the prevalence of diabetes diagnosis has climbed from 4.9 percent in 1990, to 11.3 percent in 2010, the prevalence of vision loss is also expected to rise.
Fang Ko, MD, also of Johns Hopkins, led a study to assess the prevalence of NVI and factors associated with risk of visual impairment. The study included data from the National Health and Nutrition Examination Survey (NHANES), a representative sampling of the US population.
For the study, Ko and colleagues had a total of 19,951 participants 20 years and older fill out questionnaires, conduct lab tests, and undergo physical examinations. The participants were used in two separate study experiments: 9,471 in the first experiment from 1999-2002 and 10,480 in the second, which ran from 2005-2008.
Using a visual acuity of <20/40 as a guideline for vision impairment, the team found that prevalence of NVI increased 21 percent, from 1.4 percent in 1999-2002 to 1.7 percent in 2005-2008. They also discovered that visual impairment increased 40 percent among non-Hispanic Whites 20-39 years old (from 0.5 percent to 0.7 percent).
In the analysis, the study team factored in older age, poverty, lower education level and diabetes diagnosed 10 or more years ago. Among these risk factors, only diabetes has increased in prevalence between the two time periods in the study. Diabetes prevalence increased 22 percent overall from 2.8 percent to 3.6 percent; and 133 percent among non-Hispanic Whites 20-39 years old (0.3 percent to 0.7 percent).
While the study cannot prove that diabetes was behind the rise in vision impairment, the other factors that were associated with NVI were either the same or better in the latter study population compared to the earlier one.
“The only (association) that got worse and got dramatically worse is diabetes, and not just diabetes, but diabetes for a long time,” Friedman told Genevra Pittman of Reuters Health.
“If the current finding becomes a persisting trend, it could result in increasing rates of disability in the U.S. population, including greater numbers of patients with end-organ diabetic damage who would require ophthalmic care,” wrote the study authors. “These results have important implications for resource allocation in the debate of distribution of limited medical services and funding. Continued monitoring of visual disability and diabetes, as well as additional research addressing causes, prevention, and treatment, is warranted."
Vision problems related to diabetes develop when fluid accumulates in the retina, causing blurriness. Also, blood vessels grow in the back of the eyes due to lack of oxygen, further complicating the matter.
Friedman noted that the type of vision loss measured in the study isn´t blindness, but would make it harder for people to live independently and would force a lot of people to either give up driving or have restrictions in place.
David C. Musch, PhD, MPH, and Thomas W. Gardner, MD, MS, both of the University of Michigan, Ann Arbor, wrote in an accompanying editorial that the results “are indeed meaningful, considering the cohort of young people for whom a milieu of sociodemographic and lifestyle factors have led to increased risk of type 2 diabetes and its consequences, which include nonrefractive visual impairment.”
“This report should send an important message to pediatricians, family practitioners, internists, and ophthalmologists who already are seeing an increase of type 2 diabetes among their younger patients, and should alert public health planners, who need to prepare for the effects on the health care system,” they continued. “The findings of Ko et al should also stimulate funding for new and ongoing efforts to prevent the underlying causes that lead to diabetes and its complications such as obesity-prevention programs aimed at children and adolescents.”
"This is probably only one of a number of signs that will be evident in the near future if we continue to have young children and adolescents be overweight and obese," Musch said in a Reuters Health interview, noting that more children and adolescents are being diagnosed with what used to be considered "adult onset" diabetes.