Cystoid macular edema (CME) is caused by leakage of fluid into the retina. Cysts form from the leakage in the center of the retina, which can be seen best with fluorescein angiography (FA) and optical coherence tomography (OCT).
The leakage is usually from inflammation. The inflammation can be from cataract surgery, lens implantation, retinal detachment, uveitis, diabetic retinopathy and macular degeneration. Depending on how serious the cause is, determines what treatment is done.
Vitrectomy surgery may be required to remove the vitreous gel, which may be pulling on the macula. This can cause inflammation and leakage. It is important to realize that CME can result even following cataract surgery. In fact, as many as 25% or so of patients may have CME after cataract surgery. In most cases, however, the vision is not significantly affected.