Definition: Diabetes can harm the eyes. It can damage the small blood vessels in the retina, the back part of your eye. This condition is called diabetic retinopathy.
Diabetes also increases the chance of having glaucoma, cataracts, and other eye problems.
Diabetic retinopathy is caused by damage from diabetes to blood vessels of the retina. The retina is the layer of tissue at the back of the inner eye. It changes light and images that enter the eye into nerve signals, which are sent to the brain.
The chance of developing retinopathy and having a more severe form is higher when:
- You have had diabetes for a long time.
- Your blood sugar (glucose) has been poorly controlled.
- You also smoke or you have high blood pressure or high cholesterol.
If you already have damage to the blood vessels in your eye, some types of exercise can make the problem worse. Check with your health care provider before starting an exercise program.
Other eye problems that can occur in people with diabetes include:
- Cataract — Cloudiness of the eye lens.
- Glaucoma — Increased pressure in the eye that can lead to blindness.
- Macular edema — Blurry vision due to fluid leaking into the area of the retina that provides sharp central vision.
- Retinal detachment — Scarring that may cause part of the retina to pull away from the back of your eyeball.
High blood sugar or rapid changes in blood sugar level often cause blurred vision. This is because the lens in the middle of the eye cannot change shape when it has too much sugar and water in the lens. This is not the same problem as diabetic retinopathy.
Most often, diabetic retinopathy has no symptoms until the damage to your eyes is severe. This is because damage to much of the retina can occur before your vision is affected.
Symptoms of diabetic retinopathy include:
- Blurred vision and slow vision loss over time
- Shadows or missing areas of vision
- Trouble seeing at night
Many people with early diabetic retinopathy have no symptoms before bleeding occurs in the eye. This is why everyone with diabetes should have regular eye exams.
Your eye doctor will examine your eyes. You may first be asked to read an eye chart. Then you will receive eye drops to widen the pupils of your eyes. Tests you may have involve:
- Measuring the fluid pressure inside your eyes (tonometry)
- Checking the structures inside your eyes (slit lamp exam)
- Checking and photographing your retinas (fluorescein angiography)
If you have the early stage of diabetic retinopathy (nonproliferative), the eye doctor may see:
- Blood vessels in the eye that are larger in certain spots (called microaneurysms)
- Blood vessels that are blocked
- Small amounts of bleeding (retinal hemorrhages) and fluid leaking into the retina
If you have advanced retinopathy (proliferative), the eye doctor may see:
- New blood vessels starting to grow in the eye that are weak and can bleed
- Small scars forming on the retina and in other parts of the eye (the vitreous)
This exam is different from going to the eye doctor (optometrist) to have your vision checked and to see whether you need new glasses. If you notice a change in vision and see an optometrist, make sure you tell the optometrist that you have diabetes.
People with early diabetic retinopathy may not need treatment. But they should be closely followed by an eye doctor who is trained to treat diabetic eye diseases.
Once your eye doctor notices new blood vessels growing in your retina (neovascularization) or you develop macular edema, treatment is usually needed.
Eye surgery is the main treatment for diabetic retinopathy.
- Laser eye surgery creates small burns in the retina where there are abnormal blood vessels. This process is called photocoagulation. It is used to keep vessels from leaking, or to shrink abnormal vessels.
- Surgery called vitrectomy is used when there is bleeding (hemorrhage) into the eye. It may also be used to repair retinal detachment.
Medicines that are injected into the eyeball may help prevent abnormal blood vessels from growing.
Follow your eye doctor’s advice on how to protect your vision. Have eye exams as often as recommended, usually once every 1 to 2 years.
If you have diabetes and your blood sugar has been very high, your doctor will give you new medicines to lower your blood sugar level. If you have diabetic retinopathy, your vision can get worse for a short time when you begin taking medicine that quickly improves your blood sugar level.
Many resources can help you understand more about diabetes. You can also learn ways to manage your diabetic retinopathy.
- Diabetes Canada — https://www.diabetes.ca/
- Fighting Blindness Canada — https://www.fightingblindness.ca/
Managing your diabetes may help slow diabetic retinopathy and other eye problems. Control your blood sugar (glucose) level by:
- Eating healthy foods
- Getting regular exercise
- Checking your blood sugar as often as instructed by your diabetes provider and keeping a record of your numbers so you know the types of foods and activities that affect your blood sugar level
- Taking medicine or insulin as instructed
Treatments can reduce vision loss. They do not cure diabetic retinopathy or reverse the changes that have already occurred.
Diabetic eye disease can lead to reduced vision and blindness.
Call for an appointment with an eye doctor (ophthalmologist) if you have diabetes and you have not seen an ophthalmologist in the past year.
Call your doctor if any of the following symptoms are new or are becoming worse:
- You cannot see well in dim light.
- You have blind spots.
- You have double vision (you see two things when there is only one).
- Your vision is hazy or blurry and you cannot focus.
- You have pain in one of your eyes.
- You are having headaches.
- You see spots floating in your eyes.
- You cannot see things on the side of your field of vision.
- You see shadows.
Good control of blood sugar, blood pressure, and cholesterol are very important for preventing diabetic retinopathy.
DO NOT smoke. If you need help quitting, ask your provider.
Women with diabetes who become pregnant should have more frequent eye exams during pregnancy and for a year after delivery.
American Diabetes Association. 11. Microvascular complications and foot care: standards of medical care in diabetes – 2019. Diabetes Care. 2019;42(Suppl 1):S124-S138. PMID: 30559237 www.ncbi.nlm.nih.gov/pubmed/30559237.
Skugor M. Diabetes mellitus. In: Schachat AP, Sadda SVR, Hinton DR, Wilkinson CP, Wiedemann P, eds. Ryan’s Retina. 6th ed. Philadelphia, PA: Elsevier; 2018:chap 49.