Diabetes mellitus is a condition that can have an effect on the small blood vessels of the body. One location of such small blood vessels is the retina in the eye. When the retinal blood vessels are affected, this is a condition called diabetic retinopathy.

Diabetic retinopathy development increases with the duration of the diabetes. It is unusual to see clinical signs of diabetic retinopathy prior to ten years after the onset of the disease.  Diabetic retinopathy can progress with time, and has become the leading cause of legal blindness in working-aged adults.  Our knowledge of treatment of diabetic retinopathy has increased over the last several years and blindness due to diabetes is becoming less frequent.  In addition to treatment of the retina directly, recent studies have shown that strict blood sugar control can decrease the onset and progression of diabetic retinopathy.

Clinically, diabetic retinopathy is divided into two broad categories, non-proliferative and proliferative retinopathy.

Non-proliferative Diabetic Retinopathy

Non-proliferative Diabetic Retinopathy is caused by damage to the walls of the normally present retinal blood vessels. The damage to the walls of the vessels results in leakage of blood and fluid from the small blood vessels.  This leakage can result in swelling of the retina, like a sponge taking up water. If the swelling involves the macula (center of the vision) then vision is affected. Fatty material (lipid) can leak from blood vessels and can result in more permanent loss of vision. More severe damage to the retinal blood vessels can result in closure of vessels and decreased blood flow to areas of the retina. If this loss of blood flow and nutrition involves the center of the vision, significant loss of vision can result.

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Proliferative Diabetic Retinopathy

Proliferative diabetic retinopathy results when there is the development of abnormal ("neovascular") blood vessels in addition to the normally present retinal blood vessels. Neovascularization results from the vascular damage resulting in lack of blood flow and nutrition to large areas of the retina. The retina becomes "starved" for oxygen, and a chemical signal is sent from damaged retina to induce the body to grow new blood vessels. This is the body's response to provide more oxygen to those areas, but the new blood vessels are fragile and grow from the surface of the retina into the vitreous "jelly" in the center of the eye. The movement of the vitreous "jelly" and the new blood vessels can result in rupture of the fragile vessels, resulting in bleeding into the center of the eye. With time, the abnormal blood vessels can scar over, contract, and pull on the surface of the retina. This pulling can cause the retina to come away from the back of the eye (retinal detachment) and can result in permanent blindness.

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Treatment

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Laser Photocoagulation

Laser Photocoagulation can be used to achieve one of two goals. Laser can either cauterize blood vessels that are leaking to stop leakage or it can destroy damaged retinal tissue by creating scarring.

In non-proliferative diabetic retinopathy, vision loss can be caused by leakage from retinal blood vessels. Laser is applied to the areas of leakage to try to decrease leakage and allow the body to reabsorb leaked material. The laser is often guided by a photograph test known as fluorescein angiography. This test is performed in the office by injecting an intravenous fluorescein dye while photos are taken of the dye circulation through the retina. The risk of significant visual loss can be reduced by the use of laser in non-proliferative diabetic retinopathy.

In proliferative diabetic retinopathy, new, abnormal, blood vessel growth develops due to damaged retina that sends out chemical signals.  Laser in this situation is applied to try to ablate damaged retina by creating scarring.  If damaged retina is destroyed, new blood vessel growth will regress. This ablation of damaged retina requires the application of many (often more than 1000) laser burns to the peripheral retina. This may be done in one or multiple sessions, and can be done with or without anesthetic injection around the eye.

Significant visual loss can be reduced by up to 66% with the use of laser in proliferative diabetic retinopathy. There can be side effects of this more intense laser treatment, such as decreased night vision, decreased peripheral vision, and blurring of central vision.

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Vitrectomy Surgery

Vitrectomy surgery is indicated when there is bleeding into the center of the eye that persists and cannot be treated with laser. At times, scar tissue formation from abnormal blood vessel growth can cause pulling on the retina and retinal detachment. Vitrectomy surgery is microscopic surgery with small instrumentation that is used to remove vitreous, blood, and certain scar tissue. Damage that results in the need for vitrectomy surgery is often advanced, and the goals of surgery are often to regain ambulating vision, but not particularly reading vision.

Central Florida Retina is involved in pharmaceutical research in diabetic retinopathy.  Patients who qualify are treated in a study to evaluate the potential benefits of systemic medications that may alter the course of diabetic retinopathy. Such patients are treated for diabetic retinopathy in the traditional manner in addition to receiving the medication.

In summary, vision can often be maintained in diabetes. Strict blood sugar control and regular examinations for early detection are critical elements in maintaining as much vision as possible. The incidence of diabetic retinopathy goes up after 10 years of diabetes, and the frequency of examination will be determined by your eye specialist.  Very close monitoring of diabetic retinopathy is necessary during pregnancy, as progression can occur. If changes of diabetic retinopathy threaten visual loss, laser photocoagulation should be considered. We often can maintain vision at a certain level, but regaining vision lost is usually not possible.

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