Diabetes and the Eye
Prevention Is Best
Diabetes is a common disease in the United States and the most common cause of blindness in the US. Regular eye examinations are important in diabetes because diabetic eye disease and the vision loss caused by it are often times preventable. Diabetes damages blood vessels in the retina of the eye allows for a higher rate of glaucoma, causes cataract and participates in dry eyes.
Diabetic Eye Disease
When discussing diabetes and its effect on the eye, a basic understanding of the anatomy of the eye and the way diabetes affects certain structures of the eye is helpful.
The retina is a thin layer of light-sensitive tissue that lines the back of the eye and is a primary site of diabetic damage to the eye. Light rays are focused onto the retina. Images are then transmitted to the brain and interpreted as the pictures you see. The macula is a very small area at the center of the retina. It is the macula that is responsible for your pinpoint vision, allowing you to read or recognize a face. The surrounding part of the retina, called the peripheral retina, is responsible for your side or peripheral vision.
There are three main problems in the eye that can occur with diabetes:
Background Diabetic Retinopathy
With Background Diabetic Retinopathy, damaged blood vessels in the retina begin to leak extra fluid and small amounts of blood into the surrounding retina. Your retina will eventually clear the blood away, but some debris is often left behind. These clumps of debris are called hard exudates and can begin to weaken the retina’s function and blur vision if they become too numerous in the macula area of the retina.
Diabetic Macular Edema (swelling)
Basic background diabetic retinopathy does not usually cause significant vision loss unless swelling (collected fluid from leaking vessels) occurs near the very center part of the retina called the macula. If you have swelling here, it is called diabetic macular edema. This is a common cause of mild to severe vision loss among diabetic patients and should be treated in many cases as noted below.
Proliferative Diabetic Retinopathy
When many of the blood vessels in the retina close, preventing enough blood flow to various areas, this is called Proliferative Diabetic Retinopathy. In an attempt to supply blood to the area where the original blood vessels closed, the retina responds by growing new blood vessels either near the nerve, or in the peripheral retina. These new vessels are fragile and not normal, and they almost always lead to eventual bleeding that scars the back of the eye. Proliferative diabetic eye disease is less common than background diabetic eye disease, but it is much more likely to take away some or all of the vision and indicates a definite need for treatment as noted below.
Who needs Treatment?
Background and early proliferative diabetic retinopathy have no symptoms. The only way to know if you have these changes and need laser therapy to save your sight is to visit your eye doctor regularly. People with diabetes should have their eyes examined at least once a year to make sure they do not have early damage that threatens their vision. If caught early, diabetic macular edema and proliferative diabetic eye disease can be treated with laser or injection therapy to save your vision. If the vision is neglected and lost, it is very hard or impossible to restore it.
Treatment for Macular Edema
Diabetic Macular Edema is treated with injectable medications into the eye that stabilize the blood vessels and allow the fluid that has leaked out of vessels to be reabsorbed. Alternatively, laser can be used to seal the leaking vessels and allow fluid to be reabsorbed. Each treatment type has its value based on the type and amount of leakage.
Treatment for Proliferative Diabetic Retinopathy
Proliferating vessels are treated by using medications that are injected into the eye and cause the newly growing, abnormal, bleeding vessels to wither away. Alternatively, treating the unused, far peripheral retina with laser, allows the more limited blood supply of the eye to be used by the important central part of the back of the eye (the macula) and allows the new, bleeding and abnormal vessels to shrink away, since the eye senses that the new vessels are no longer needed after the laser. Each treatment type has its advantages and disadvantages, so patients should consult with their doctor to determine which treatment is best for their circumstance.