How does diabetes affect my eyes?
Diabetes affects your eyes when your blood glucose, also called blood sugar, is too high.
You are not likely to have vision loss from high blood glucose. People sometimes have blurry vision for a few days or weeks when they are changing their diabetes care plan or medicines. High glucose can change fluid levels or cause swelling in the tissues of your eyes that help you to focus, causing blurred vision. This type of blurry vision is temporary and goes away when your glucose level gets closer to normal.
If your blood glucose stays high over time, it can damage the tiny blood vessels in the back of your eyes. Such damage can begin during pre-diabetes, when blood glucose is higher than normal, but not high enough for you to be diagnosed with diabetes. Damaged blood vessels may leak fluid and cause swelling. New, weak blood vessels may also begin to grow. These blood vessels can bleed into the middle part of the eye, lead to scarring, or cause dangerously high pressure inside your eye.
Most serious diabetic eye diseases begin with blood vessel problems. The four eye diseases that can threaten your sight are
The retina (which is the inner lining at the back of each eye) senses light and turns it into signals that your brain decodes, so you can see the world around you. Damaged blood vessels can harm the retina, causing a disease called diabetic retinopathy. In early diabetic retinopathy, blood vessels can weaken, bulge, or leak into the retina. This stage is called non-proliferative diabetic retinopathy.
If this gets worse, some blood vessels close off, which causes new blood vessels to grow, or proliferate, on the surface of the retina. This stage is called proliferative diabetic retinopathy. These abnormal new blood vessels can lead to serious vision problems.
Diabetic macular edema
Diabetes can lead to swelling in the macula (the part of your retina that you need for reading, driving and seeing faces), which is called diabetic macular edema. Over time, this disease can destroy the sharp vision in this part of the eye, leading to partial vision loss or blindness. Macular edema usually develops in people who already have other signs of diabetic retinopathy.
Glaucoma is a group of eye diseases that can damage the optic nerve, that is, the bundle of nerves that connects the eye to the brain. Diabetes doubles the chances of having glaucoma, which can lead to vision loss and blindness if not treated early.
Symptoms depend on which type of glaucoma you have.
The lenses within our eyes are clear structures that help provide sharp vision—but they tend to become cloudy as we age. Patients with diabetes are more likely to develop cloudy lenses, called cataracts. People with diabetes can develop cataracts at an earlier age than people without diabetes. Researchers think that high glucose levels cause deposits to build up in the lenses of your eyes.
Who is more likely to develop diabetic eye disease?
Anyone with diabetes can develop diabetic eye disease. Your risk is greater with high blood glucose that is not treated, when high blood pressure is not also treated and High blood cholesterol and smoking may also raise your risk for diabetic eye disease.
If you have diabetes and become pregnant, you can develop eye problems very quickly during your pregnancy. If you already have some diabetic retinopathy, it can get worse during pregnancy. Changes that help your body support a growing baby may put stress on the blood vessels in your eyes. Your health care team will suggest regular eye exams during pregnancy to catch and treat problems early and protect your vision.
Diabetes that occurs only during pregnancy, called gestational diabetes, does not usually cause eye problems.
Your chances of developing diabetic eye disease increase the longer you have diabetes.
What are the symptoms of diabetic eye disease?
Often there are no early symptoms of diabetic eye disease. You may have no pain and no change in your vision as damage begins to grow inside your eyes, particularly with diabetic retinopathy.
When symptoms do occur, they may include
Blurry or wavy vision, Frequently changing vision—sometimes from day to day, Dark areas or vision loss, Poor color vision, Spots or dark strings (also called floaters) and Flashes of light.
Everyone needs to have their eyesight tested to check for vision and eye problems on a yearly basis. For diabetic patients however, this should be done every six months if there is no established eye disease.
Getting comprehensive dilated eye exams is especially important because some eye diseases may not have warning signs. The exams are the only way to detect these diseases in their early stages, when they are easier to treat.
The exam includes several tests: A visual field test to measure your side (peripheral) vision. A loss of peripheral vision may be a sign of glaucoma.
A visual acuity test, where you read an eye chart about 20 feet away, to check on how well you see at various distances.
Tonometry, which measures your eye’s interior pressure. It helps to detect glaucoma.
Dilation, which involves getting eye drops that dilate (widen) your pupils. This allows more light to enter the eye. This provides a clear view of important tissues at the back of your eye, including the retina, macula, and optic nerve.
The key is getting early discovery and early treatment to prevent total visual loss.
Folasade Olaitan Alli
Adult Cardiologist Consultant at Lagos Executive Cardiovascular Centre