Understanding The Link Between Diabetes And Vision Loss
Education and Advocacy Vision loss and blindness have become a tragic reality for many Canadians living with diabetes. Nearly 60,000 have experienced sight impairment because of eye damage due to diabetic retinopathy.
Left untreated, diabetic retinopathy could lead to diabetic macular edema (DME), a serious vision-threatening condition, which is now the leading cause of blindness and partial sightedness for those under the age of 50.
The impact is serious on many fronts. Aside from robbing these Canadians of their sight, they miss many of life’s most precious moments — seeing a child in cap and gown at their graduation, or the stunning colours of a sunset.
The ability to see also plays an important role in being able to manage diabetes itself, from reading blood sugar levels on a glucose monitor to dosage instructions on prescription bottles.
A 2007 study by the CNIB found that there were economic and other health consequences for the 40 percent of Canadians with diabetic retinopathy under age 65. Only one-third of this group was employed and an estimated 50 percent with vision loss struggled to live on a yearly income of $20,000 or less. The group also experienced three times as much depression and four times the risk of hip fractures, compared to Canadians without vision loss.
How diabetes plays a role
Sight problems and diabetes are closely connected. Dr. Subrata Chakrabarti, Professor and Chair of Pathology and Laboratory Medicine, Western University in London, Ontario, explains that “fluctuations in blood glucose (sugar) in people with diabetes can cause injury to the tiny blood vessels that nourish the retina, which can cause damage over time and lead to diabetic retinopathy.” The retina is a thin, light-sensitive layer at the back of the eye. It acts like film in a camera, capturing images taken by the eye’s lens, then turning that information into signals for the brain.
In fact, nearly all patients with Type 1 diabetes and 60 percent of those with Type 2 diabetes develop some form of diabetic retinopathy in the first 20 years after the onset of the disease. Guidelines from the Canadian Diabetes Association recommend screenings take place annually for Type 1, and upon diagnosis of diabetes, then every one to two years for Type 2. The longer you have had the disease, the higher the risk of retinopathy.
“Fluctuations in blood glucose (sugar) in people with diabetes can cause injury to the tiny blood vessels that nourish the retina, which can cause damage over time and lead to diabetic retinopathy.”
Disease management and prevention
While new pharmacologic treatments are available for patients with DME, their success depends on both early detection and initiation of therapy. According to Dr. Keith Gordon, Vice-President of Research at the CNIB, “Early detection of DME is important, since early treatment means improved success in preventing vision loss or maintaining current levels of vision.”
That means being diligent about scheduling annual checkups with your eye doctor, and being aware of early symptoms. For example, if you experience dark spots, large floaters — dots, circles, or lines — that move across your field of vision, or blurred vision, you should consider booking an appointment with an eye doctor right away.
“It is imperative for everyone with diabetes to see an eye doctor regularly — not just those with detectable DME,” he says. In its early stages, DME, a buildup of fluid behind the eye, may not show any symptoms.
Treatment for vision loss
If DME is present, a doctor may suggest anti-VEGF medications, like EYLEA (aflibercept) or Lucentis (ranibizumab). These are injected into the eye to slow or stop the growth of abnormal blood vessels. “Both have been shown to be more effective than laser treatment,” explains Dr. Gordon. “They are highly effective in reducing vision loss due to DME, and, in some cases, may restore some lost vision.”
Dr. David Chow, Co-Director of the Toronto Retina Institute, agrees. He also notes, “these drugs represent a huge step forward. Compared to 20 years ago, we are doing so much better at treating DME. But treatments can only do so much. They aren’t cures. If a patient does not manage their diabetes, they may be back.” Maintaining healthy blood sugar and blood pressure levels and adequate exercise are critical for preventing vision loss in diabetics.
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