Estimated to affect more than 20.8 million people in the United States, diabetes is the leading cause of vision loss among adults between the ages of 20 and 74. But that does not have to be an inevitability. “Prevention —a safe prescription for all complications of diabetes—may be the only efficient prescription for retinopathy,” says Mara Lorenzi, MD, in a recent Current Diabetes Reports.¹ Dr. Lorenzi is associate professor of ophthalmology at Harvard University and director of the Center for Diabetic Retinopathy at the Schepens Eye Research Institute.

The American Diabetes Association and the American Academy of Ophthalmology both recommend annual eye examinations for all persons with diabetes. And yet last year the CDC estimated that 6.2 million diabetic Americans remain undiagnosed. Herein lies a daunting reality of this disease: Because diabetes generally often goes undiagnosed, and diabetic retinopathy has few visual or ophthalmic symptoms until vision deteriorates, the opportunity for early detection is often missed.

Case of the hiding patients. “First of all, we have to identify patients at risk for developing diabetic retinopathy. There are millions of people who aren’t diagnosed,” said Michael Colucciello, MD, clinical associate at the University of Pennsylvania, Philadelphia, and in private practice in Moorestown, N.J.

Deborah Schlossman, MD, staff ophthalmologist at Beth Israel Deaconess Medical Center in Boston, concurred. “The most important factor from an ophthalmologist’s perspective is early detection. Recommendations for patients with type 1 diabetes include an eye examination within the first five years of onset and then at least annually. Patients with type 2 diabetes should be examined as soon as they’re diagnosed and then at least annually,” Dr. Schlossman said.

Clinical Management

The Academy has outlined six goals for the management of diabetic retinopathy:

• Identify patients at risk for diabetic retinopathy.
• Encourage involvement of the patient and primary care physician in the management of the patient’s systemic disorder, with specific attention to control of blood sugar, serum lipids and blood pressure.
• Encourage and provide lifelong evaluation of retinopathy progression.
• Treat patients at risk for visual loss.
• Minimize the side effects of treatment that might adversely affect the patient’s vision and/or vision-related quality of life.
• Provide visual rehabilitation for patients with visual loss from the disease or refer for visual rehabilitation.²

The vital three. Diabetic retinopathy occurs in a fairly predictable pattern, so it’s relatively easy to recognize and manage the risk factors for progression during early onset. For those who are diagnosed, maintaining target ranges of blood pressure, glucose and lipid levels can have a dramatic effect on diabetes management and progression of retinopathy.

Pressure. Control of hypertension alone reduces the risk of microvascular complications by approximately 33 percent, according to the CDC. Unfortunately, only about one-fifth of patients diagnosed with diabetes maintain the recommended target blood pressure of 130/80.

Glucose. The severity of hyperglycemia is also a risk factor associated with the development of retinopathy. Controlling blood glucose levels is imperative for all persons with diabetes.

Lipids. Hyperlipidemia has been directly correlated with the development of intraretinal lipid exudates. According to the results of the Wisconsin Epidemiological Study of Diabetic Retinopathy, the presence of retinal hard exudates is associated with increased cholesterol levels in patients using insulin.³ Careful control of lipid levels can prevent these accumulations.

Dr. Colucciello reiterated the results of the EuroDiab trial, “which indicated that we should consider treating all diabetics with ACE inhibitors regardless of whether or not they have high blood pressure to help prevent microvascular complications.” Lisinopril, the ACE inhibitor used in this investigation, “reduced progression of retinopathy in nonhypertensive patients with type 1 diabetes by 50 percent over two years.” ⁴

Inform and involve your patient. “Patient education is very important. Patients need to be educated not only by primary care physicians, endocrinologists, and diabetic support groups, but also by ophthalmologists. The more that the patients know about their disease, the better their outcomes are going to be. We have to provide education and encourage them to get evaluated periodically so we can address problems as they occur,” said Dr. Colucciello.

Dr. Schlossman agreed, “Primary care physicians should have pamphlets and brochures to explain to patients why it’s important to have regular dilated eye examinations with an ophthalmologist. Videos in their offices to educate patients about diabetic retinopathy would be useful as well. I often show my patients their retinal photographs and describe the findings. This helps them to understand and visualize any damage that is occurring, and can motivate them to keep follow-up appointments and control their blood sugar and associated medical conditions.”

Patients must also be encouraged to become proactive in their own diabetes management. Important lifestyle changes such as improved diet and more exercise are critical factors in the prevention of diabetic retinopathy and vision loss. Dr. Colucciello recommended that ophthalmologists should “emphasize to patients that treatment is not only about medication but also lifestyle changes.”

Treatments: Many Are Here, More Are Coming

“We have more medications than ever now at our disposal for treating diabetes, in addition to diet and exercise, to improve the chances of diabetic control,” Dr. Colucciello said.

When further treatment is required, said Dr. Schlossman, “laser treatment and vitrectomy surgery have been very effective in controlling many of the ocular complications related to diabetes. Newer treatment modalities such as intravitreal steroids and vascular endothelial growth factor inhibitors are also being evaluated.”

Caution with the glitazones. “Physicians prescribing glitazones should be aware of the possibility of decreased vision associated with the development of macular edema. Caution should be exercised when thiazolidinediones [a class of insulin-sensitizing agents used for treatment of type 2 diabetes] are used in those with nephropathy, especially when combining the glitazone with insulin. Options for management of rosiglitazone-induced macular edema with vision loss include dose reduction or discontinuation,” warned Dr. Colucciello.⁵

“There is still some distance to go before we have available effective adjunct drugs for the prevention of retinopathy, but the field is moving. The goal is to be able to target the effects of hyperglycemia with a variety and diversity of drugs, such as those available today to target hypertension. An immediate challenge is to devise new modalities for moving the promising results emerging from prevention studies in experimentally diabetic animals to prevention trials in human diabetes,” said Dr. Lorenzi.

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1 Curr Diabetes Rep 2006;6:102–107.
2 Preferred Practice Pattern, Diabetic Retinopathy, American Academy of Ophthalmology, www.aao.org/education/library/ppp/dr_new.cfm.
3 Klein, R. et al. Ophthalmology 2003;110(11):2118–2125.
4 Chaturvedi, N. et al. Lancet 1998;351(9095):28–31.
5 Colucciello, M. Arch Ophthalmol 2005;123:1273–1275.