If you have diabetes – whether Type 1 or Type 2 – there’s one thing you should do every year, without fail: Get a dilated eye exam with your optometrist or ophthalmologist.

“Diabetes is known to alter the health of the blood vessels in the retina and these vascular changes do not cause symptoms in the early stages,” said Dr. Jeffrey Sundstrom, ophthalmologist and retina specialist at Penn State Health Eye Center. “It’s extremely important to detect any changes early so we can take steps to prevent vision loss – and the way to do that is with an annual dilated eye exam.”

More than half of people with diabetes will develop diabetic retinopathy, one of the leading causes of legal blindness in the U.S., yet fewer than half of patients with diabetes get their annual screenings. Women who develop gestational diabetes are also at risk for diabetic retinopathy and should be seen multiple times throughout their pregnancy.

Multiple threats to eyesight

Diabetes can lead to vision loss in several ways, Sundstrom said.

The blood vessels in the retina often become leaky, and this results in swelling of the macula ― the part of the retina at the back of the eye that is responsible for high acuity central vision. Diabetes can also cause ischemia, or poor blood flow to the macula, which can lead to vision loss.

“Severe vision loss from diabetes can occur when abnormal blood vessels grow in the retina and into the vitreous ― the gel portion of the eye. These abnormal blood vessels can lead to bleeding in the back of the eye and even cause a type of retinal detachment,” Sundstrom said. “If any of these conditions are left untreated, they can lead to progressive visual loss and blindness.”

Several treatments available

Historically, laser treatment was used to stop vascular leakage and reduce swelling. These treatments slowed down the rate and reduced the chances of having severe vision loss.

Newer drugs, available since the mid-2000s, improve vision in patients with vision loss from diabetic retinopathy, Sundstrom said. The medication, given as injections into the eye, inhibits the vascular endothelial growth factor (VEGF) ― a protein that promotes the leakage and growth of abnormal blood vessels.

“Depending on where the vascular abnormalities are, we start treatment with anti-VEGF or laser. We will use these treatments at various times to achieve optimal visual results,” Sundstrom said. “Once retinopathy develops, the patient will need to be seen more frequently, and the treatment will depend on how active the disease is.” 

In severe cases, patients may need surgery to remove blood from the eye or repair a detachment, he said.

Know your ABCs

In addition to annual dilated eye exam, patients should focus on other medical risk factors. Overall, paying attention to your ABCs is the best way to manage diabetes – and lower your risk for vision loss as well as heart attack, stroke and all the issues that diabetes can cause, Sundstrom said. 

"A" stands for the hemoglobin A1C test, which tracks whether your blood glucose is under control. For those with diabetes, the target is below 6.5%.

"B" stands for blood pressure; "C" for cholesterol, which should be below 200 mg/dL.

“Patients should work with their primary care doctor to optimize all three of the ABCs, and see their eye care provider for annual diabetic retinopathy screening exams,” Sundstrom said. “The key to maintaining good vision is a good relationship with both your primary care provider and your eye doctor.”

The good news is that if you manage your ABCs and get an annual dilated eye exam, most patients with diabetes can retain good vision, he said.

Related content:

• The Medical Minute: Controlling diabetes apart from blood sugar levels
• The Medical Minute: Diabetes sparks a rise in neuropathy

The Medical Minute is a weekly health news feature produced by Penn State Health. Articles feature the expertise of faculty, physicians and staff, and are designed to offer timely, relevant health information of interest to a broad audience.