Glaucoma And Diabetes: Awareness Can Save Your Sight

People who have diabetes are at higher risk for developing glaucoma, a group of degenerative eye diseases that cause blurred vision, loss of vision and, if left untreated, blindness.

January is National Glaucoma Awareness Month, the perfect time to remind ourselves why a yearly eye exam is important. Although some types of glaucoma trigger distressing symptoms, the most common type, called open-angle, does not. An eye exam is necessary to detect this problem.

Diabetes and Glaucoma

A research study done at the Michigan Kellogg Eye Center revealed the risk of open-angle glaucoma increases 35 percent for people with diabetes alone. Individuals having hypertension alone have a 17 percent higher risk. The likelihood of developing glaucoma rises 48 percent for those with both diabetes and hypertension.

"The study reinforces the importance of regular eye examinations for patients at increased risk of glaucoma, including those with diabetes and hypertension," said researcher Dr. Joshua D. Stein.

Other risk factors for glaucoma are a positive family history, being over 40, Asian-American or African-American heritage, and a history of severe eye injury.

Glaucoma’s Angle: What Glaucoma Is

For us to see, light must go through the curved covering of our eyes, or cornea, and then pass through a pocket called the anterior chamber. The anterior chamber contains a protective fluid called aqueous humor. From there, light travels through the hole (pupil) in our colorful iris, through the vitreous—a fluid filled chamber—and then strikes the back or our eye, or retina.

At the cusp of the anterior chamber, where the cornea and iris join, is an area of the eye called the angle. The angle is a drainage system for the anterior chamber's aqueous humor. Glaucoma develops when the angle becomes partly or completely blocked.

Varieties of Glaucoma

Open-angle glaucoma occurs when the eye’s angle, or drainage system, becomes inefficient. As the drainage of aqueous humor slows, pressure in the eye increases. Vessels carrying blood to the retina and optic nerve become pinched reducing the oxygen and nutrients those parts of the eye receive. Damage is gradual, and there are typically no warning signs.

Angle-closure glaucoma develops when the iris blocks the entrance to the angle, or drainage canal. Pressure in the eye can build quickly causing pain, red eye, headache, blurred vision, nausea, and vomiting. This is an emergency situation. If not addressed immediately it may lead to blindness. However, angle-closure usually occurs more slowly and is called chronic angle-closure glaucoma.

Neovascular glaucoma is rare but associated with diabetes. If the eye’s blood vessels are damaged by diabetic retinopathy, the retina manufactures new, abnormal blood vessels. Should these vessels grow on the iris, they can clog the eye’s angle, preventing aqueous fluid drainage and increasing eye pressure. This is difficult to treat. The abnormal blood vessels may be reduced with laser surgery, and some people are helped by drainage implants.

Normal-tension glaucoma, when the optic nerve is damaged although eye pressure is not very high, has not been linked to diabetes.

Ounce of Prevention: Yearly Eye Exam

If an eye exam reveals that you have open-angle glaucoma, you will likely be treated with medication or laser surgery. The medication, usually eye drops, either increases drainage or decreases the production of aqueous fluids. Angle-closure glaucoma can be addressed with a laser procedure called peripheral iridotomy. In severe cases of glaucoma, surgeons may perform a trabeculectomy, remodeling the eye’s angle, or drainage system.

Sources:Glaucoma.org; Science Daily; Carolina Eye Care; Diabetic Care Services