Diabetes Mellitus

Diabetes mellitus is a condition that impairs the body's ability to use and store sugar. Elevated blood sugar levels, excessive thirst, an increase in urine excretion and changes in the body's blood vessels are all characteristic of the disease. Diabetics are also more subject to having fluctuations in vision associated with their blood sugar. It is also more common for diabetics to have cataracts, glaucoma and significant blood vessel disorders in the back of the eye.

Blindness from diabetic retinopathy is an important public health problem and is responsible for at least 10-15% of all blindness and 20% of new blindness between the ages of 45 and 75.

Statistics show that at least 8.5 people per 100,000 are registered as legally blind from diabetes, meaning that at least 20,000 Americans are affected. This number is certainly conservative as the number is quite a bit higher. In addition to the 20,000 people that are blind, more are visually handicapped and impaired.

The risk of blindness caused by diabetes is related to the duration of the disease. One must also remember that diabetes is a vascular disease and a progressive disease.

Diabetes is a disease that affects approximately 10 million people in the United States at this time. The risk of developing diabetic retinopathy is high in patients who have had diabetes for a long period of time. About 60 percent of patients who have had diabetes for 15 years or more have some blood vessel damage in their eyes. Only a small percentage of those developing retinopathy, however, have a serious problem with vision and an even smaller percentage ever become blind.

In spite of this, diabetic retinopathy is the leading cause of new blindness among adults in the United States and diabetic patients are said to be about 25 times more prone to blindness than non-diabetics. Of the 10 million people in the United States with diabetes, it is estimated that about 40 percent of these people have some degree of eye involvement.

Diabetes affects the eye permanently through changes in the blood vessels of the retina. These changes, which are known as diabetic retinopathy, can occur in different forms.

The first of these, which is the less serious of the two, is known as background retinopathy. Fortunately, vision is usually not seriously affected and the condition does not progress in about 80% of diabetic patients. In some cases, however, the leaking fluid collects in the macula, the center of the retina, which is responsible for central vision.

Straight ahead images, reading and close work might then become blurred, and the loss of central vision can result in legal blindness even though this is "the lesser" of the two. Background retinopathy is certainly a warning sign that can progress to the more serious sight-endangering stages and merits close follow-up.

The more significant form of proliferative retinopathy begins the same as background retinopathy, with the addition of new blood vessel growth on the surface of the retina or on the optic nerve. These fragile new blood vessels may rupture and bleed into the vitreous, or the clear gel-like substance that fills the center of the eye. The leaking blood clouds the normally clear vitreous. Light passing from the lens through the vitreous to the retina is then blocked and images are distorted. Blood vessels may even grow on the iris and cause a form of glaucoma. Loss of sight and even blindness can result from this condition.

Early Diagnosis

In the treatment of diabetic retinopathy, the most important factor to remember is early diagnosis. All diabetic patients should have at least yearly ophthalmic eye exams, including detailed retinal evaluations.

Control of the diabetes, using medication or diet alone, can help retard the changes in the back of the eye. The best way to control the sugar level in your body is by having a medical doctor follow your diabetes and help regulate your medication and diet. The exact cause of the diabetic retinopathy is not completely understood.  However, it is known that diabetes weakens the small blood vessels in various areas of the body. Pregnancy, high blood pressure and lack of control of your diet and blood sugar can adversely affect these factors.

The ophthalmologist should determine if retinopathy is developing and evaluate treatment options. Many of the changes from diabetes are not progressive and will not need further treatment.

The development of a new or fragile blood vessel in the back of the eye, from diabetes, sets the stage for later serious complications. Fluorescein angiography is an important method in diagnosing and evaluating diabetic retinopathy. This test is done in the office. Dye is injected into the arm. With the use of a special retinal camera, through rapid sequence photography, the dye will define the integrity of the blood vessels in the back of the eye. This will give us a dynamic flow to better evaluate which blood vessels, if any, are leaking and where they are at risk. By carefully reviewing these photographs, we can identify any abnormality and advise whether treatment is needed.

The method of treatment indicated is photocoagulation with a laser beam. There are different types of lasers and dyes that can be used. Argon or "dye lasers" are the most common. Krypton is used in certain areas. This is used to treat certain vascular conditions.

The principal treatment for diabetic retinopathy is retinal photocoagulation with the lasers mentioned above. For this procedure, a laser beam is used and energy rays are focused on the retina. These rays can cause small burns and destroy the areas of leakage (from these abnormal blood vessels) and attempt to prevent new blood vessels from forming in the retina. The destruction in the back of the eye, or retina, decreases the impetus of new blood vessel formations.

It has been proven conclusively that in certain diabetic conditions, this photocoagulation can retard proliferative retinopathy, thus preventing progress of the disease process.

Photocoagulation can either be done as a "focal treatment," which is one or two specific areas, or as a panretinal treatment, which is diffused across the retina and requires multiple treatments. Photocoagulations are relatively non-painful and are done on an outpatient basis. No anesthetic or pain medication is necessary.

It is sometimes necessary to do this treatment in various stages. If the blood has already gotten to the back of the eye and is causing fibrous tissue to form, then a vitrectomy may be needed.  This process involves making an incision into the side of the eye to remove the blood-filled vitreous gel-like material and the scar tissue from the back of the eye. This is not a simple operation and carries significant risks and complications.

The goal of early diagnosis and treatment is to avoid the need for this level of surgery.  However, if needed, this is one modality that can be used to thwart further progression of the disease.

The laser beam is a high-energy light that is transformed into heat. When heat is absorbed, the eye tissue will coagulate. The coagulation can seal leaking tissue, destroy diseased tissue and cause scar formation. The goal of laser surgery is to seal the holes or breaks in the leaking blood vessels of the retinal and choroidal tissues in order to prevent further deterioration of the retina.

Lasers are also used to destroy tissue and abnormal blood vessel growth. Diseases which may benefit from the Argon or "dye laser" photocoagulation surgery are the following:  diabetic retinopathy; maculopathy of the aging, or neovascularization from the choroids; central serous chorioretinopathy; subretinal neovascularization; retinal holes and tears; retrial branch vein occlusions; and retinal arterial macro-aneurysms and various tumors. As with all surgical procedures, there are potential dangers, complications and risks. Though the possibility is slight, there is a chance of displacing the laser beam, causing hemorrhages and excessive scar formation. As with any surgical intervention, one must weigh the potential hazard, complications, risks and alternatives in the context of the condition this it is treating.

In this context, it is a relatively "safe" procedure. The problem with this laser treatment is that laser treatment does not, in most cases, improve vision but attempts to maintain the vision that you have and prevent the condition from deteriorating.

As with all vascular eye and medical problems, early diagnosis and treatment is significant. If you find there are severe diabetic complications in the back of your eye, the earlier the treatment is instituted, the better the results. If you wait until serious symptoms are present before seeking help, treatment modalities are unfortunately somewhat more limited.

PREVENTION AND EARLY TREATMENT ARE THE CORNERSTONES OF SUCCESSFUL PREVENTION OF SERIOUS DIABETIC CHANGES.

The advent of new medications have offered additional means of treating vascular diseases of the eye.