Retinal Problems With Diabetes
The most common disease treated by retinal specialists is damage caused by diabetes. Diabetes can be a devastating disease and is second only to cataracts as the leading cause of blindness in the United States.
The damage caused by the diabetes is usually found first in the retina before it affects the rest of body and most commonly takes the form of diabetic retinopathy.
What is Diabetes?
Diabetes is a metabolic disorder in which the body is either intolerant of or cannot properly use insulin. Insulin is a hormone that essentially turns glucose into energy, or stores it as fat, and in a diabetic, this hormone is unable to keep blood sugar levels in the normal range either because the body cannot process it correctly or has built up a tolerance to it so that more insulin is needed to keep blood sugar levels stable.
Because of the inefficiency of insulin in diabetic patients, the blood sugar typically remains at a higher range and therefore causes damage to nerve fibers and blood vessels among other things. The blood vessels in the retina are usually the first to show this type of damage. They become weakened and eventually breakdown and leak.
To compensate for this leaking, the retina grows new blood vessels, which is called neovascularization. These new blood vessels are typically very weak and only cause more damage to the retina. Neovascularization can also cause swelling of the macula, called macular edema, as well as vitreous hemorrhage.
Normal Retina Image
Diabetic retinopathy usually has no warning signs or symptoms and typically occurs in patients who have been diabetic for a few years, usually over ten. However, brittle diabetics, or diabetics who cannot control their blood sugar, may have retinopathy within just a few months or years.
There are two types of diabetic retinopathy:
- Background diabetic retinopathy, or BDR
- Proliferative diabetic retinopathy, or PDR
Background diabetic retinopathy is the beginning stage of the disease and is characterized by dot blot hemorrhages (see photo below), microaneurysms (small vascular buds), and lipoid exudates, or fat cells that leak from blood vessels under the macula. The lipoid exudates can cause the macula to swell leading to cystoid macular edema, or CME.
Proliferative diabetic retinopathy is characterized by neovascularization, the growth of new blood vessels into the retina. These blood vessels grow from the optic disc, or branch off from other blood vessels on the retina. They can also grow into the iris and cause what is known as neovascular glaucoma. The blood vessels themselves can rupture and cause retinal or vitreous hemorrhages. They can also bundle up into a mass that can pull on the retina and separate it from the back wall of the eye creating a retinal detachment.
The Face of Diabetic Retinopathy
Diagnosis of Retinal Issues
Diagnosing diabetic retinopathy is rather straight forward. Usually most ophthalmologists will order a fluorescein angiogram to verify what was seen during their exam of the retina. A fluorescein angiogram is a series of photos taken with a special filter after injecting the patient with a vegetable-based dye known as fluorescein. This dye highlights leaking blood vessels and allows the ophthalmologist to pinpoint areas of the retina to be treated, as well as confirm the diagnosis. I’ve seen a number of patients actually get the diagnosis of diabetes from their eye doctor first because of damage found in their retina.
Treatment of Diabetic Retinal Problems
Once the diagnosis has been made, there are various treatment options depending on the needs of the patient.
Both types of diabetic retinopathy receive the same treatment: panretinal photocoagulation, or PRP. PRP uses an argon laser to seal leaking or weak blood vessels or prevent further neovascularization. Using this technique prevents further bleeding and consequently further damage to the retina. In the case of neovascularization, the laser destroys the new, weak blood vessels preventing further growth and any possible leaking. Several thousand laser burns are usually required to complete the treatment, which usually requires two or more treatment sessions. Ongoing laser treatment may be required depending on the severity of the diabetes.
Focal laser photocoagulation is the treatment of choice for macular edema. The laser beam is focused to pinpoint accuracy and used to seal the microaneurysms that lie below the macula and cause the swelling. This has been shown it significantly improve the visual prognosis.
Intravitreal triamcinolone acetonide, also known by the brand name Kenalog, can also be used to treat macular edema. Kenalog is a corticosteroid that reduces inflammation and fluid build-up or edema. These treatments are very successful, but have significant risks. Since Kenalog is a steroid, it can cause cataracts as well as increased intraocular pressure, also called glaucoma. The treatment also needs to be repeated about every three months since the effects are not permanent. Kenalog is usually used in conjunction with laser therapy.
Anti-VEGF (vascular endothelial growth factor) drugs such as Avastin, Lucentis and Macugen have been shown to improve the prognosis of macular edema. Usually used in conjunction with laser therapy, anti-VEGF drugs prevent the formation of neovascular blood vessels. These treatments, like Kenalog, are not permanent and need to be repeated about every three to six months. In my experience, this treatment was the most widely successful and limited the need for laser therapy.
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Retinal and Vitreous Hemorrhages
Retinal hemorrhages are typically treated with laser to seal the leaking blood vessels, and sometimes anti-VEGF treatment to help the body reabsorb the blood. Some retinal hemorrhages involve the vitreous, the gel-like substance that gives the eye its rigidity and shape.
Vitreous hemorrhages almost always require a vitrectomy. Most physicians will observe the hemorrhage (to see if the body will reabsorb the blood) for about a month, sometimes more. If the hemorrhage does not show signs of resolving, however, vitrectomy will be necessary.
A vitrectomy involves removing the vitreous from the eye through a probe, and inserting silicon-based oil in its place. Recovery time is lengthy, sometimes taking 6 months to 1 year, and there is further risk of retinal detachment, and another vitreous hemorrhage.
Prevention of Diabetic Retinal Damage
Unfortunately, there is no true prevention for diabetic retinal disease, except the prevention of diabetes itself. Keeping the blood sugar levels stable and incorporating an exercise program into the daily routine can delay the onset of such diseases. However, the longer the patient lives with diabetes, the more damage the disease causes. It’s only a matter of time before it takes its toll.
Changing the diet has been shown to help control the blood sugar. Switching to a vegetarian or vegan diet has been shown to reverse diabetes in some cases (including my own). If you are currently in the early stages of the disease, or are “pre-diabetic” changing your diet and losing weight can greatly reduce your risk of developing the full blown disease. Taking vitamins such as vitamin C in large doses has been shown to improve the body’s ability to utilize insulin and decrease the risk factors for the disease.
This information is by no means conclusive, and is not meant to replace a doctor’s expertise. It should give you a good idea of what to expect should you or someone you know have or develop diabetes. Always see your ophthalmologist right away if you have any visual disturbances or sudden loss of vision.
You may enjoy reading a couple of my other articles about diabetes and eye health in general.
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© 2012 Melissa Flagg OSC