What Is Diabetic Retinopathy?
Diabetes is a condition in which the body's ability to process and store sugar has been impaired. Among the characteristics of the disease are gradual changes in blood vessels. Diabetic retinopathy is a complication of diabetes caused by the deterioration of blood vessels nourishing the retina at the back of the eye.
As the blood vessels weaken, they may leak fluid or blood into the clear vitreous mass that fills the eye or becomes enlarged, damaging the delicate retina.
Who Is At Risk?
Persons who have had diabetes for a number of years are especially at risk of developing diabetic retinopathy. Six in ten who have had diabetes for over 15 years show symptoms of retinal damage; high blood pressure and pregnancy both worsen the condition. Although diabetic retinopathy is easily detected during routine eye examinations and treatable with laser surgery in the early stages, it is the leading cause of new blindness among adults. Diabetics are 25 times more likely to become blind than those without the disease.
Two Types Of Retinopathy
The two types of diabetic retinopathy are background retinopathy and proliferative retinopathy.
In background retinopathy, blood vessels weaken and begin to leak blood and serum. These fluids collect and form deposits in the retinal tissues, causing it to swell. If the leaking blood vessels are in the peripheral area of the eye, no serious visual impairment usually occurs. However, if the fluid collects in the macula - the area of the retina responsible for straight-ahead, detail, and color vision - blind spots and blurred vision can make activities such as reading and drive difficult or impossible.
In the second, and more advanced stage of diabetic retinopathy, the abnormal cells rapidly spread - proliferative - across the inner surface of the retina. These weakened vessels can bleed into the vitreous and stop light from reaching the retina. In addition, the connective scar tissue, which forms as a result of the ruptured blood vessels, can shrink, pulling the retina away from its underlying structure, causing it to detach. Severe loss of sight - even blindness - may result.
What To Look For
There is no pain associated with either form of retinopathy. A gradual blurring of vision may occur. But changes in the eye can go undetected without a medical eye exam. When bleeding occurs in proliferative retinopathy, the patient may see spots, a clouding of vision, or experience a complete loss of sight in the affected eye.
Detection And Diagnosis
There are numerous instruments and techniques that eye doctors use to examine the retina.
The slit lamp combines a microscope with strong illumination. It is often used with a hand-held lens, allowing us to see portions of the retina in far greater detail.
The ophthalmoscope is frequently used to examine both the central and peripheral retina. In both procedures, your pupils will first be dilated allowing the retina to be examined under bright light and magnification.
Some patients are given an intravenous injection of fluorescein dye in a procedure called fluorescein angiography. The dye, which takes only moments to reach the eye, makes tiny blood vessels visible, enabling photographs to be taken for careful study. At The Lincoln Eye & Laser Institute, we use the latest in digital imaging to allow an immediate analysis of your fluorescein angiography. This helps us perform laser in a more timely manner and explain to you and your family what is wrong with the retina and how best to treat you.
Treatment Of Retinopathy
Your doctor will take into account your age, medical history, lifestyle, and the degree of damage to the retina before recommending a course of action. In many cases, treatment is not required; in others, laser treatments may be recommended to halt further progression of the disease.
In cases of background retinopathy, the laser is focused with pinpoint accuracy on the damaged blood vessels. The heat from the laser seals the vessels and helps bond the retina to the back of the eye by forming minute scars.
One common treatment for proliferative retinopathy is called pan-retinal photo-coagulation. In this procedure, the peripheral retina is scattered with laser light beams, like the pattern made by a shotgun. Although a certain amount of healthy tissue is destroyed, this technique usually stops further growth of abnormal cells and preserves the macula, saving valuable straight-ahead and color vision.
Removal Of The Vitreous
If the vitreous has become too clouded with blood to clear on its own, a procedure called a vitrectomy may be recommended. In this technique, the vitreous is drained and replaced with a clear, artificial solution. An immediate improvement in sight is noted in about 70% of cases.
Retinal detachment occurs when the transparent layer of the retina separates from the pigment layer. As the cones and rods contained in the transparent layer are lifted away, vision becomes darkened and distorted. Complete detachment leads to complete loss of vision.
Reattachment surgery is done under general anesthesia. First, retinal breaks will be located and frozen using cryotherapy. Next, the vitreous fluid is drained from behind the transparent layer. Finally, a silicone band is wrapped around the eye to indent it and push the transparent and pigment layers back into contact with each other. The scar tissue, which forms in the frozen areas, reattaches the layers.
If you have diabetes, your eyes are almost certain to be affected. Early detection and diagnosis of diabetic retinopathy are important if good vision is to be maintained. As there are no symptoms in the early stages, regular checkups by an eye care professional are vital.