How is a macular edema treated?
Macular edema is treated with laser treatment, injection of medications into the eye, or both. Focal laser treatment involves the application of small laser burns to distinct areas of leaky blood vessels within the macula, whereas grid laser treatment applies laser burns over a larger area of the macula and is used to treat more widespread fluid edema. These laser burns slow the leakage of fluid and reduce the amount of fluid in the retina. This treatment is usually completed in one session, but additional treatments may be needed. Laser therapy of macular edema may or may not improve vision, but has been proven to decrease the chances of further vision loss over time by 50% based on the landmark Early Treatment of Diabetic Retinopathy Study. Medications injected into the eye for macular edema include steroids and so-called VEGF inhibitors (for example, Lucentis™ and Avastin™). Both of these treatments, especially the latter, have been shown to decrease retinal swelling and improve vision in patients with diabetic macular edema. Steroids and anti-VEGF drugs are increasingly being used in tandem with laser treatment.
A patient may need focal laser surgery more than once to control the leaking fluid. If you have macular edema in both eyes and require laser surgery, generally only one eye will be treated at a time, usually several weeks apart.
Focal laser treatment stabilizes vision. In fact, focal laser treatment reduces the risk of vision loss by 50%. In a small number of cases, if vision is lost, it can be improved. Contact your eye care professional if you have vision loss.
What are the side effects of treatments for macular edema?
Both focal and grid laser treatment may result in new, small blind spots in a person’s vision. Steroid injections may result in elevated internal eye pressure and glaucoma that requires treatment. The newer anti-VEGF medications appear to have a good safety profile overall (similar drugs used intravenously to treat colon cancer have shown a small but definite increased risk for blood clots), but often require multiple injections over time.
Photos Courtesy of the National Eye Institute
How is diabetic retinopathy treated?
No treatment is needed during the first three stages of diabetic retinopathy unless a patient has macular edema (although research suggests that laser treatment may be effective for severe nonproliferative retinopathy in some patients with type 2 diabetes). To prevent progression of diabetic retinopathy, people with diabetes should control their levels of blood sugar, blood pressure, and blood cholesterol.
The gold-standard for treatment of proliferative retinopathy is laser therapy. The doctor applies 1000 to 2500 laser burns throughout the peripheral retina (areas outside of the macula). This procedure is referred to as panretinal photocoagulation (PRP) or scatter laser treatment, and helps to shrink abnormal blood vessels that bleed into the eye and cause retinal detachment. Because a higher number of laser burns is necessary, two or more sessions usually are required to complete treatment. PRP has been proven to reduce the chances of severe vision loss from proliferative retinopathy by up to 75%. Importantly, PRP works better before the fragile, new blood vessels have started to bleed. That is why it is important to have regular, comprehensive dilated eye exams. If bleeding or fibrous scar tissue growth are severe, patients may need a surgical procedure called a vitrectomy. During a vitrectomy, the vitreous gelatin filling the inside of the eye and blood contained therein are removed, thereby improving vision and reducing the risk of any or further retinal detachment. More recently, anti-VEGF drugs are starting to be used in addition to PRP for the treatment of proliferative retinopathy.
Scatter laser treatment works better before the fragile, new blood vessels have started to bleed. That is why it is important to have regular, comprehensive dilated eye exams. Even if bleeding has started, scatter laser treatment may still be possible, depending on the amount of bleeding.
If the bleeding is severe, you may need a surgical procedure called a vitrectomy. During a vitrectomy, blood is removed from the center of your eye.
What are the side effects of treatment for proliferative retinopathy?
Patients often notice a loss of peripheral (side) vision and more difficulty with night vision after PRP treatment; a newer type of PRP called subthreshold diode micro-pulse laser appears to minimize these side effects by using less laser energy, but has not been widely tested or adopted by retinal specialists as of yet. Vitrectomy surgery often results in cataract formation and, potentially, retinal detachment – but is proving more and more effective with advances in surgical instruments and technique, especially in patients with severe vitreous hemorrhage and type 1 diabetes.
What happens during laser treatment?
Both macular and scatter (PRP) laser treatment are performed in your doctor's office or eye clinic. Before the surgery, your doctor will dilate your pupil and apply drops to numb the eye. The area behind your eye also may be numbed to prevent discomfort.
The lights in the treatment room will be dim and you will place your chin on a chin rest of an eye microscope with a laser attached. The doctor will hold a special lens to stabilize your eye and begin applying the laser through your pupil to the retina at the back of the eye. During the procedure, you will hear a clicking noise with each laser application and may see flashes of light and feel a sensation of heat that may create a stinging sensation that can be uncomfortable (especially in younger patients).
It is advisable to have someone to drive you home after this treatment. Because your pupil will remain dilated for a few hours, you should bring a pair of sunglasses.
For the rest of the day, your vision will probably be a little blurry. If your eye hurts, your doctor can suggest treatment.
What is a vitrectomy?
If the retina is becoming detached as a result of proliferative retinopathy, or if there is a significant amount of blood in the center of the eye (vitreous gel) that does not clear within several months, you may need a vitrectomy surgery to help prevent blindness or restore your sight. If vitrectomy surgery is needed in both eyes, they are usually done several weeks apart. A vitrectomy typically is performed under local anesthesia. Several small incisions are made in the eye. Next, several small instruments are inserted to cut abnormal fibrous scar tissue attached to the retina and remove the vitreous gelatin as well as any large amounts of blood . The vitreous gel is replaced with a salt solution that functions the same as the original vitreous gel. Patients typically return home after a vitrectomy. The operated eye will be red and sensitive (though new surgical instruments and techniques have dramatically improved this) and patients are asked to wear an eye patch for a few days to protect the eye. Eye drop medications also will be prescribed to protect against infection and reduce inflammation caused by the surgery.
Are PRP (scatter laser treatment) and vitrectomy effective in treating proliferative retinopathy?
Yes. Both treatments are very effective in reducing vision loss. People with proliferative retinopathy have less than a 5% chance of becoming blind within five years when they get timely and appropriate treatment. Although both treatments have high success rates, they do not cure diabetic retinopathy.
Once patients have proliferative retinopathy, they always will be at risk for new bleeding and loss of circulation to the retina. Patients may need treatment more than once to protect your sight.
What can I do if I already have lost some vision from diabetic retinopathy?
If you have lost some sight from diabetic retinopathy, ask your eye care professional about low vision services and devices that may help you make the most of your remaining vision. Ask for a referral to a specialist in low vision. Many community organizations and agencies offer information about low vision counseling, training, and other special services for people with visual impairments. A nearby school of medicine or optometry may provide low vision services.
Reviewed by Dr. A. Paul Chous, MA OD, FAAO. 4/12
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