Causes of Cystoid Macular Edema

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In what situations does cystoid macular edema occur? The most common time for cystoid macular edema to occur is about 1 to 2 months after cataract surgery. Clinically significant cystoid macular edema occurs after 2 or 3 out of every 100 cataract operations, and can happen even if the surgery was performed perfectly. Other causes of cystoid macular edema include diabetes affecting the retina, retinitis pigmentosa, age-related macular degeneration, strokes of the retina, or a variety of conditions causing chronic inflammation inside the eye.

Diagnosing Cystoid Macular Edema

Our retina specialists, Dr. Leonard Kirsch and Dr. Richard Hairston will determine the diagnosis and cause of cystoid macular edema by taking an extensive history and by performing a very detailed examination of your retina using special microscopes and lenses. The doctor may also recommend a test called a fluorescein angiogram. This test involves injecting a vegetable dye into a vein in the arm and taking black and white photographs of the retina using a special camera (these pictures are NOT X-rays). The photographs allow the doctor to confirm the diagnosis of cystoid macular edema, to determine where the leaky blood vessels are located, to discover how much leakage is occurring, and to guide treatment recommendations.

Treatment of Cystoid Macular Edema

What will happen if we don’t treat clinically significant cystoid macular edema? If the edema fluid stays in the retina for many months, it can cause permanent damage to the macula and the vision may never be normal. Therefore, some form of treatment is recommended for almost everyone with significant cystoid macular edema.

The treatment that the specialists at The Eye Institute of West Florida recommend for cystoid macular edema is custom-designed for your individual situation. The treatment depends especially on the underlying cause of the cystoid macular edema. If you have cystoid macular edema following cataract surgery, the initial treatment (often started already by the cataract surgeon) is eye drops and perhaps an oral medication called Diamox. If the cystoid macular edema does not respond to this treatment, the next step involves an injection of prednisone medication behind the eye. This injection is done in the office after numbing the skin of the eye. The injections are usually painless, although the eye may feel swollen and sore for a day or two afterwards. The eyelid may also become droopy but this will usually go away by itself. The doctor then allows 6 to 8 weeks for the medication to take effect and re-examines the retina. Up to 3 injections may be required to cure the cystoid macular edema. Treatment with injections is successful in 80% to 90% of patients. If the cystoid macular edema is not cured using the injections behind the eye, injections of steroid medications and/or Avastin into the eye itself may be performed. Avastin is a medication that inhibits a molecule called vascular endothelial growth factor (VEGF) and is most commonly used for wet age-related macular degeneration. Recent clinical research has indicated that Avastin may be a safe and effective treatment for cystoid macular edema. Although it is used “off-label” for all eye diseases because it has only been approved to treat metastatic colon cancer, Avastin has become a standard of care for a number of eye problems over the past few years. Any of these intraocular injections are also painless and performed in the office, although there is slightly more risk than incurred with the injections behind the eye. Risks of any injection into the eye include infection, bleeding, retinal detachment, cataract formation, and increased eye pressure (glaucoma); these are rare occurrences and can usually be treated. You will be given antibiotic drops for four days following this injection. The injections may be repeated about every 6 weeks if the edema persists or recurs. If the injections do not resolve the problem then surgery may be recommended.

The operation for cystoid macular edema is performed in the regular operating room at the Largo Ambulatory Surgery Center and is almost always performed under local anesthesia. You may go home the same day or stay overnight in the hospital. The risks of this operation include retinal detachment (occasionally), infection inside the eye (rarely) and bleeding inside the eye (rarely). These complications are treatable most of the time, although as with any surgery inside the eye, loss of eyesight can rarely result.

The surgery is called a vitrectomy because the vitreous gel inside the eye is removed through 3 tiny incisions that do not require stitches. The vitreous gel is replaced with salt water (the vitreous is like your appendix; you have it but you are sometimes better off without it!). If there is scar tissue on the surface of the retina, the doctor will remove it during surgery. Using special microscopic forceps, the scar tissue is peeled from the surface of the retina like you would peel a label from its backing. You will wear an eye patch for the first night and must use drops for several weeks afterwards. The operation has better than a 90% success rate.

Laser Treatment of Cystoid Macular Edema

For cystoid macular edema due to diabetes or a stroke in the retina, laser treatment is usually recommended as the first choice. Using a contact lens placed on the front of the eye and a state-of-the-art laser, the doctor places mild laser spots in the macula. The procedure is painless, takes less than 5 minutes, and is performed in the office. The major side effect is that some patients actually see the laser spots after the treatment is finished; these usually fade away over the next few weeks. The macular edema may take up to four months to go away. If the swelling does not go away after that time or it comes back later, the laser treatment can be repeated.

Maintaining Vision

As you can see, the diagnosis and treatment of cystoid macular edema is complex and is best performed by a retina specialist. We hope that you more clearly understand the different choices available and which may be the best for your situation. Working together with Dr. Kirsch or Dr. Hairston, you can choose a treatment plan with which you are most comfortable and which has the highest chance of restoring and maintaining your precious gift of sight.