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Diabetes can lead to blindness: How to save your sight

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If you have diabetes, annual eye exams could save your sight.

While the Academy of Ophthalmology and the American Diabetes Association urge all people over 65 to have yearly eye exams, “we also recommend annual exams if you have diabetes or a significant family history of diabetes,” says Rishi Singh, M.D., an ophthalmologist at Cleveland Clinic Cole Eye Institute.

Type 2, or adult-onset, diabetes affects more than 30.3 million Americans, including one-fourth of those over 65, reports the U.S. Centers for Disease Control and Prevention.

Of those with diabetes, a quarter are unaware they have it — or the threat of vision loss.

How does diabetes erode eyesight?

Diabetes’ destruction to eyes, nerves, organs and limbs stems from the body failing to make or effectively use insulin, a hormone secreted by the pancreas.

You can think of insulin and the pancreas that pumps it out as your internal Amazon Prime team: They process and ship blood glucose from your food to your body’s cells.

When your inner shipping service operates smoothly, blood sugar serves as your chief energy source. But, if you have too many packages (that is, surplus blood sugar) or a sluggish or striking worker (the pancreas), glucose camps out in your bloodstream rather than reaching your cells.

That process can spur vision loss and, ultimately, blindness.

“The earlier you’re diagnosed with diabetes, the better your visual outcome will be,” Singh says. “The goal is to find changes before damage is irreversible.”

Diabetes is a disease that affects small blood vessels. Excess blood sugar damages the body’s smallest blood vessels and impairs blood flow, which starves the tissues capillaries feed. This leads to leaking blood vessels, swelling and other dire complications.

Fluid leaks can mutate the shape and size of the eye’s lens, causing cataracts. These leaks also can harm the retina — the back of the eye — where visual images are formed.

Diabetes can produce hemorrhages (bleeding) and edema (excess fluid) in the retina that can have a serious effect on vision.

Diabetes-related vision issues

If someone has poorly managed diabetes for 20 years, they have a 90% chance of diabetes-caused damage to the retina (aka diabetic retinopathy), says Dr. Gareth Lema, M.D., Ph.D., a retina surgeon at New York Eye and Ear Infirmary of Mount Sinai in Manhattan.

Vision loss from diabetic retinal detatchment

Diabetic retinopathy is the fourth leading cause of blindness in the world.

“Both bleeds and retinal detachment require surgery but even then, severe vision loss may be permanent,” he says.

Swelling in the retina, called macular edema, can occur at any stage of diabetes. “It is the leading cause of vision loss secondary to diabetes,” Singh says.

Famished capillaries also fuel glaucoma, an eye disease that injures the optic nerve.

SEE RELATED: Diabetic retinopathy: What it is, how it's treated

Importance of eye exams for diabetics

“The majority of patients with diabetes have no visual symptoms. They may experience blurred or wavy vision or patches of missing sight without realizing these are serious,” Singh says. “Eye exams can help find these conditions early, before they cause long-term, irreversible vision loss or blindness.”

Man receiving eye exam due to diabetic-related vision loss

Not just any visual exam will do. A full comprehensive vision examination is necessary. Eyes should be dilated with drops, allowing your doctor to perform a thorough retinal exam.

“The drops open up the pupil, which is critical,” Singh says. “That’s why it’s vital to get your eyes dilated by an optometrist or ophthalmologist.”

Treatments for diabetes-related vision issues

Intermediate stages of diabetic eye disease can be aided by laser surgery and injections — to the eyes — of a medicine that prevents swelling of the retina and growth of abnormal blood vessels (called

), Lema says.

Such injections improve vision in one-third of patients and stabilize the overabundance of capillaries in nine of 10, reports the American Academy of Ophthalmology.

The A1C blood test  can reveal how well your glucose is managed by measuring the amount of sugar sticking to hemoglobin molecules within your cells.

Diabetes and overall health

Unchecked or poorly controlled surplus sugar harms not only your eyes, but also your heart, nerves, kidneys and feet. This may lead to heart disease, stroke, the need for dialysis, lower-limb amputation and possible neuropathies, painful electrical storms within your nervous system.

“Diabetics have to manage their blood sugar, to consciously think about the function that the rest of our bodies do automatically,” Lema says.

This is where primary care physicians and endocrinologists can assist — saving not only your sight but your overall health.

Page updated October 2019

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