Innovation Spotlight - Diabetic Eye

Diabetic eye may be predictor of future health risks

Ophthalmologists should refer patients with retinopathy, macular edema for cardiovascular care

By Edward Edelson
Reviewed by Ronald Klein, MD

Madison, WI-An ophthalmologist who looks into the eyes of a diabetic patient may be able to predict that patient's future health, said Ronald Klein, MD.
That view is an especially strong indicator of the risk of death from heart disease and stroke, because the blood vessels in the diabetic eye are a marker for abnormalities in other blood vessels in the body.
So when the eyes show signs of diabetic retinopathy, macular edema, or other diabetes-related problems, these patients should be under care for cardiovascular disease, Dr. Klein reported in an article in Archives of Ophthalmology.

Predicting risk of death

Dr. Klein's study also shows that diabetic eye problems predict the patient's risk of death from all causes as far as 16 years in the future.
"There should be a public health benefit accrued from identifying such individuals and monitoring them for heart disease," the article stated.
It is the ophthalmologist's responsibility to take action by making the proper referral, added Dr. Klein, professor in the Department of Ophthalmology and Visual Sciences at the University of Wisconsin Medical School, Madison, WI.
"Our data suggest that diabetic patients with diabetic retinopathy should be evaluated by a primary-care doctor for the presence of cardiovascular disease," he said.
"Our data suggest that diabetic patients with diabetic retinopathy should be evaluated by a primary-care doctor for the presence of cardiovascular disease," he said.
Diabetic patients from an 11-county area in Wisconsin were enrolled in the study between 1980 and 1982. Of those enrolled, 996 had young-onset diabetes. They were diagnosed at age 30 or under and were taking insulin. There were 1,370 older-onset diabetics, diagnosed at age 30 or older. All were examined for visual acuity, diabetic retinopathy, macular edema, and cataract, among other diabetes-related ocular conditions.
While previous studies have found decreased survival rates associated with cataract, visual impairment, and diabetic retinopathy, Dr. Klein said that there is a dearth of studies looking at the association between specific diabetes-related eye conditions and specific causes of death.
Dr. Klein and his colleagues in Wisconsin followed their patients for 16 years. In that time, there were 214 deaths in the younger-onset patients, representing 21.5% of the group, and 996 deaths in the older patients, 72.7% of that group, in which the causes of death could be confirmed.
The researchers then went back to their original diagnoses of eye condi tions and found the relationships between specific conditions and specific causes of death.
At the outset, the prevalence and severity of retinopathy was higher in the younger-onset group. The older patients had a higher prevalence of visual impairment, cataract, and glaucoma. The prevalence of macular edema was similar in both groups: 11.2% in the younger patients and 12.1% in the older patients.
Heart disease and stroke were the leading causes of death in both groups. Cancer was listed as an immediate or underlying cause of death in just 1.9% of the younger patients and 16.2% of the older patients. Stroke was similarly listed for 2.8% of the younger patients and 19.4% of the older patients, with ischemic heart disease listed for 14.3% of the younger patients and 59.4% of the older patients.
The number of deaths from stroke in the younger patient group was not large enough to establish a relationship with ocular conditions, the researchers found.
But there were clear relationships between death from heart disease, ranging from a hazard ratio of 1.58 for the presence of cataract in the first examinations to a ratio of 11.02 for the presence of retinopathy. The risk was linked to the severity of both retinopathy and visual impairment. For example, it was more than three times higher for patients with proliferative retinopathy than for those with a mild, nonproliferative form of the condition.
The relationships were reduced, but not banished, when other risk factors, such as age, sex, and blood pressure were taken into account.
In the older group of patients, the severity of retinopathy at the baseline examination predicted a higher mortality rate from all causes. Proliferative retinopathy increased the risk of fatal stroke, and visual impairment was associated with a higher rate of fatal heart disease. No increase in risk was found for the presence of cataract or glaucoma at the initial examination. No relationship was found between any eye condition and death from cancer.
These are not strikingly new findings, Dr. Klein said. Past studies have found similar relationships between diabetic eye diseases and increased risk of death from stroke and heart disease.
But the Wisconsin Epidemiologic Study of Diabetic Retinopathy, as it is called, provided "a unique opportunity to examine the relationship of specific eye conditions to survival in a large cohort of diabetic patients," Dr. Klein said.

Saving lives by referral

Lives and eyes may be saved if the ophthalmologist refers a diabetic patient with eye problems for cardiovascular care and emphasizes the need for strict diabetes care, he said.
"Measures to control cardiovascular and diabetic risk factors-good control of blood sugar, blood pressure, and blood lipids-do reduce the risk of retinopathy, coronary artery blockage, and the like," Dr. Klein said.
"Recent data from the United Kingdom Prospective Diabetes Study show that reduction of blood pressure led to a nearly 40% reduction in stroke and congestive heart failure," he added.
Dr. Klein does not have a financial interest in any aspect of this article.

Ophthalmology Times / APRIL 15, 2000