Cystoid macular edema is a swelling of the center portion of retina called the macula.  When swelling develops in the retina, the vision often is reduced.  Swelling develops from leakage of fluid from the blood vessels within the retina.  There are many causes of macular edema, but the most common causes are post-surgical (such as after cataract surgery), diabetes, inflammation (uveitis), and the use of certain medications.

An optical coherence tomography (OCT) test or fluorescein angiography (FA) test may be performed to detect and follow cystoid macular edema.  If detected, the retina physician may recommend treatments such as eye drop medication, injection of medicine into or around the eye, or laser treatment.  As the swelling resolves, the vision often improves.