Cystoid Macular Edema (CME)

Cystoid macular edema (CME) is a painless condition that affects the central retina, known as the macula. When CME is present, multiple cyst-like (cystoid) areas of fluid accumulate in the macula, causing retinal swelling or edema.

Although the exact cause of CME is not fully understood, it is often associated with various diseases such as retinal vein occlusion, uveitis, or diabetes. It most commonly occurs after cataract surgery. Approximately 1-3% of individuals who undergo cataract extraction will experience decreased vision due to CME within the first post-operative year, typically between two to four months after surgery. If CME develops in one eye, there is an increased risk (possibly up to 50%) that it will affect the other eye as well. Fortunately, most patients recover their vision with appropriate treatment.

Symptoms

  • Blurred or decreased central vision (CME does not affect peripheral or side vision)

  • Painless retinal inflammation or swelling, often following cataract surgery

These symptoms may not necessarily indicate CME. However, if you experience one or more of these signs, consult your eye doctor for a comprehensive examination.

Treatment

Since various factors can contribute to CME, treatment approaches may differ. Once the diagnosis is confirmed, your ophthalmologist may employ several treatment methods. Retinal inflammation is typically managed with anti-inflammatory medications such as cortisone or indomethacin. These are usually administered as eye drops but may occasionally be given as injections or oral medications. In some cases, diuretics like Diamox can help reduce retinal swelling.

If the vitreous (the gel-like substance that fills most of the eye) exerts traction on the macula, it may cause CME. In such cases, a vitrectomy—a surgical procedure to remove the vitreous gel—may be necessary.

In certain instances, the swelling and inflammation associated with CME can lead to glaucoma, a condition characterized by increased pressure inside the eye. If glaucoma develops, it must be treated with appropriate medications to reduce intraocular pressure.

Click here to learn more about Cystoid Macular Edema from EyeSmart’s website. EyeSmart is the American Academy of Ophthalmology's eye health information for the public.