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.
Diabetic retinopathy is a main cause of blindness in Americans 20 to 74 years old. People with type 1 or type 2 diabetes are at risk of this condition.
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 changes in blood sugar level often cause blurred vision. This is because the lens in the middle of the eye cannot change shape when there is 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 can occur to much of the retina before your vision is affected.
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.
Exams and Tests
Your eye doctor (ophthalmologist) 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.
Persons 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 neuropathy, your vision can get worse for a short time when you begin taking medicine that improves your blood sugar level.
Many resources can help you understand more about diabetes. You can also learn ways to manage your diabetic retinopathy.
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 health care 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.
Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.