Diabetes can affect eyesight. Elevated blood sugar levels may cause changes in the body’s blood vessels, the veins and arteries that carry blood throughout your body. It can cause cataracts, glaucoma, and damage to the blood vessels inside the eye.
Diabetic retinopathy is a complication of diabetes caused by changes in the tiny blood vessels of the retina. The retina is the light-sensitive nerve layer at the back of the eye that sends images to your brain. Without a retina, the eye cannot communicate with the brain, making vision impossible.
There are two types of retinopathy:
Background Retinopathy: An early stage when blood vessels in the retina are damaged. Fine blood vessels become narrowed while others enlarge to form balloon-like sacs. They may leak fluid or blood causing the retina to swell. Sight is not usually affected. In some people the fluid collects in the macula, the part of the retina that lets us see detail. The fluid makes the macula swell, blurring our vision. This is known as macular edema. Reading and close work may be difficult.
Proliferative Retinopathy: New abnormal vessels may grow fragile, brush-like branches and scar tissue as the disease progresses. These new blood vessels may rupture and bleed into the vitreous, the clear gel-like substance that fills the center of the eye. Scar tissue may form and pull the retina away from the back of the eye causing a detached retina. Abnormal blood vessels may also grow around the pupil causing glaucoma by increasing pressure within the eye. This is the most serious form of diabetic retinopathy and affects up to 20% of diabetics, and can cause sever loss of sight, including blindness.
Diabetic retinopathy is the leading cause of new blindness among adults in the USA. People with untreated diabetes are said to be 25 times more at risk for blindness than the general population.
There are no early warning signs with diabetic retinopathy. At some point you may have blurring. If new blood vessels form, they can hemorrhage and may leave spots floating in your vision. This can also be as severe as only being able to tell dark from light.
A medical examination by an ophthalmologist is the only way to find changes inside your eye. This includes visual acuity testing, pupil dilation, ophthalmoscopy, and tonometry (tests fluid pressure). Further testing may include fluorescein angiography – dye given intravenously to obtain color photographs of the retina.
The most significant treatment is laser surgery. This seals the leaky blood vessels. A small burst of light is beamed on the damaged retina. This reduces macular edema. Laser surgery retards vision loss. Other treatment such as cryotherapy and vitrectomy may be recommended for persistent hemorrhaging.
Early detection of diabetic retinopathy is the best protection against loss of vision. People with diabetes should schedule examinations by an ophthalmologist at least once a year.