Macular edema & CME is swelling of the macula, the small area of the retina responsible for central vision, of which the central 5% of the retina is most critical to vision. The edema is caused by fluid leaking from retinal blood vessels into the macula. Blood leaks out of the weak vessel walls into a very small area of the macula which is rich in cones, the nerve endings that detect color and from which daytime vision depends. Blurring occurs in the middle or just to the side of the central visual field, it can appear like one is looking through cellophane. Visual loss may progress over a period of months and can be very annoying because of the inability to focus clearly. Because the macula is surrounded by many tiny capillaries, any conditions affecting the blood circulation anywhere in the body or in the eye can cause macular edema. Retinal capillary obstruction, inflammation of the eye, and age-related macular degeneration have all been associated with macular edema. The macula may also be affected by swelling following cataract surgery, but this normally resolves itself naturally. I rarely cause a permanent loss of vision, but the recovery is often a slow, gradual process over 2 to 15 months.