by Jessica Pyhtila, PharmD, BCPS, BCGP
If you have diabetes, taking care of your eye health is extremely important. Because diabetes is the leading cause of blindness, it is important to be aware of the ways in which diabetes can harm your eyesight, and what you can do about it. Diabetes can harm vision in several ways. In the short term, high blood sugar levels can cause temporary blurry vision due to swelling of tissues inside the eye. However, over the long term, diabetes can cause more severe, and permanent, changes to the eyes. This is especially true if blood sugar is uncontrolled.
Diabetic retinopathy
The retina lines the back of each eye, allowing you to sense light. Like all tissues of the body, the retina is nourished by blood vessels. Unfortunately, when you have diabetes, these blood vessels can become damaged. In turn, your vision may be jeopardized. In the early stages of the condition, or nonproliferative diabetic retinopathy, weakened blood vessels can bulge and leak into the retina. As the condition progresses into proliferative diabetic retinopathy, vision worsens as old blood vessels close off and new, abnormal blood vessels start to grow. Further, scar tissue on the retina can cause the retina to pull away from the eye, leading to retinal detachment. About a third of people with diabetes who are 40 years of age or older have signs of diabetic retinopathy.
Treatments for diabetic retinopathy generally work by stopping the growth of abnormal blood vessels. These therapies include aflibercept (Eyelea), bevacizumab (Avastin), and ranibizumab (Lucentis). Laser treatments to stop the growth of blood vessels may also be used. In some cases, a surgery called vitrectomy, where the clear fluid of the eye is removed and replaced, may also be performed.
Diabetic macular edema
The sharp vision that is needed to read, drive and recognize faces is due to the macula portion of the retina. Swelling, or edema, in the macula can destroy crisp vision, leading to vision loss. Diabetic macular edema occurs in about half of those with existing diabetic retinopathy.
Treatments for diabetic macular edema work by stopping fluid leaks, and include aflibercept (Eyelea), bevacizumab (Avastin), and ranibizumab (Lucentis). Laser treatments may also be used.
Cataracts
Under normal circumstances, the lens of the eye appears clear. Cataracts, or cloudy lenses, can interfere with sight and cause vision loss. People with diabetes may be at a 2 to 5 times greater risk of developing cataracts than others, as high blood sugar levels may cause deposits to form on the lenses.
Treatments for cataracts are generally surgical. In cataract surgery, the lens of the eye is replaced with an artificial lens to improve vision.
Glaucoma
Glaucoma is a condition where abnormal pressures in the eye can put pressure on the optic nerve, which transmits sight signals from your eye to your brain. If the optic nerve is damaged, blindness can result. Diabetes can double your risk of developing glaucoma. A type of glaucoma called neovascular glaucoma can result from diabetic retinopathy. In this condition, abnormal blood vessels that develop in the eye can block the drainage of fluid in the eye, leading to increased pressure.
Treatments for glaucoma often include eye drops like latanoprost (Xalatan), timolol (Timoptic) and dorzolamide (Trusopt). Surgery and a laser procedure called trabeculoplasty may also be used in some cases to help drain fluid from the eye to relieve pressure.
Symptoms of Eye Problems
Vision problems from diabetes can develop slowly over time. Often, there is no pain or outward signal that anything is wrong, especially in the early stages of eye disease. However, if you experience symptoms, they may include:
· Blurry vision
· Changing vision
· Dark areas within the field of vision
· Problems with color vision
· Floating spots or dark strings
· Flashing lights
If you experience any symptoms of eye disease, it is important to contact your eye doctor. Sudden changes in vision are considered a medical emergency.
Keeping Your Eyes Healthy
You can help to keep your eyes healthy when you have diabetes in several ways. These include:
· Controlling your blood pressure, blood sugar and cholesterol levels. When they are uncontrolled, they increase the risk of eye damage.
· Quit smoking. Smoking damages blood vessels throughout your body, including the tiny, delicate vessels in your eyes.
· See your eye doctor at least once a year. Getting a dilated eye exam on an annual basis can help to identify any problems before you even have symptoms, making them easier to treat. During a routine eye exam, your doctor will also check the pressure in your eyes and your overall vision. You should get annual eye exams within 5 years of a Type 1 diabetes diagnosis, and every year if you have Type 2 diabetes. If you are pregnant, you should have an eye exam within the first 3 months of pregnancy and as ordered by your doctor after that time.
It is also important to know if you fall into a high-risk group for developing diabetes-related eye problems. These groups include:
· African Americans
· Native Americans
· Alaska Natives
· Hispanics/Latinos
· Pacific Islanders
· Older adults
Although pregnant women who develop gestational diabetes are not at high risk for developing eye problems from diabetes, women with existing diabetes who become pregnant may be at higher risk of vision complications that can develop quickly.
References:
National Institute of Diabetes and Digestive and Kidney Diseases. “Diabetic Eye Disease.” May 2017. Retrieved from https://www.niddk.nih.gov/health-information/diabetes/overview/preventing-problems/diabetic-eye-disease
Centers for Disease Control and Prevention. “Diabetic Retinopathy.” N.d. Retrieved from https://www.cdc.gov/visionhealth/pdf/factsheet.pdf
National Eye Institute. “Diabetic Retinopathy.” August 3, 2019. Retrieved from https://www.nei.nih.gov/learn-about-eye-health/eye-conditions-and-diseases/diabetic-retinopathy
