Study finds that visual impairment in T1D patients may be decreasing

American Academy of OphthalmologyOct 3 2009

Highlights of October's Ophthalmology, the journal of the American Academy of Ophthalmology, include good news on preserving vision in people with type 1 diabetes, a warning from the Cardiovascular Health Study for macular degeneration patients, and a report on how vision impacts well-being across the lifespan.

Today's Type 1 Diabetes Patients Enjoy Better Vision than Those in Decades Past

People diagnosed with type 1 diabetes (T1D) in recent years are less likely to develop diabetes-related vision loss than those diagnosed in earlier years, says a new study funded by the National Eye Institute, a division of the National Institutes of Health. Forecasts of visual impairment prevalence in T1D patients may need to be amended, the researchers suggest, since current predictions assume that the earlier incidence rates will continue. Ronald Klein, MD, MPH, and colleagues at the University of Wisconsin Department of Ophthalmology and Visual Sciences assessed visual acuity over 25 years in 955 people diagnosed with T1D in one of four time periods, with the earliest defined as "before 1960" and the latest as "1975 through 1979."

"Visual impairment in T1D patients may be decreasing for several reasons," Dr. Klein said. "Effective treatments for diabetic retinopathy (DR) and related macular edema became widely available in the 1970s, and earlier screening and detection of DR began in the 1980s. In the 1990s, we learned that intensive control of blood glucose could significantly impact DR progression in T1D, so physicians and patients began closely monitoring this factor and controlling it with diet, exercise and medication."

Key findings include: among participants who had T1D for 30 to 34 years at the time their eyes were examined for the study, impaired vision was found in 16 percent of those diagnosed from 1922 through 1959, compared with 9 percent of those diagnosed from 1970 through 1974; also, among patients who had T1D for 15 to 19 years at the time they were examined, impaired vision was found in only four percent of those diagnosed from 1975 through 1979.

Signs of Macular Degeneration May Predict Heart Disease

A large study found strong evidence that older people who have age-related macular degeneration (AMD) are at increased risk for coronary heart disease (CHD), although not for stroke. This result adds to mounting evidence that AMD and cardiovascular disease may share some risk factors -- smoking, high blood pressure, inflammatory indicators such as C-reactive protein, genetic variants such as complement factor H -- and disease mechanisms. The Cardiovascular Health Study (CHS) followed 1,786 white or African American participants, who were free of CHD or stroke at the study's outset, for about seven years. The CHS received funding from the National Heart, Lung and Blood Institute, a division of the National Institutes of Health.

The incidence of CHD was 25.76 percent in patients with AMD, compared with 18.9 percent in those without AMD. The association between AMD and CHD was somewhat stronger in people age 69 to 78 than age 79 and up. Data were adjusted to counter potentially confounding factors like hypertension, diabetes, and smoking.

"Like the recent findings on older Medicare beneficiaries, our study shows that early AMD may predict the development of CHD in an older population," said CHS researcher Tien Yin Wong, MD, PhD.

Vision Influences Adults' Success and Health; Prenatal Factors may be Crucial

Impaired vision is associated with unemployment, low socioeconomic status, and general and mental health problems, says a long-term study by researchers at the Institute of Child Health, University College London. Poor vision was also associated with low birth weight, intrauterine growth retardation, maternal smoking during pregnancy, and socioeconomic deprivation in early childhood. The findings held true for all causes and levels of impairment. This is one of the largest studies to examine the impact of visual disability on social and occupational success.

"It is interesting that key prenatal and childhood factors known to be associated with serious adult health conditions like hypertension are also associated with visual function," said Jugnoo S. Rahi, PhD, lead researcher on the study. "We think further life-span research will reveal factors that contribute both to complex eye diseases, like glaucoma and macular degeneration, and to other major illnesses that apparently share etiologies with these eye disorders," she added.

Of 9,330 study participants, 1.3 percent had socially significant visual impairment -- defined as inability to pass a driving test due to visual deficits -- and another 0.9 percent had severe visual impairment or blindness. The study examined people at age 44 or 45 for near, distance and stereo visual acuity (the ability of the eyes to coordinate to provide clear images and depth perception). Participants were drawn from the 1958 British birth cohort, comprised of everyone born in Britain within a single week in 1958. Health data gathered in clinical exams from birth to middle age was available for all participants.