Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye (a yellow central area of the retina) and causes it to thicken and swell (edema). The swelling may distort a person's central vision, as the macula is near the center of the retina at the back of the eyeball. This area holds tightly packed cones that provide sharp, clear central vision to enable a person to see detail, form, and color that is directly in the direction of gaze.
Macular edema sometimes appear for a few days or weeks after cataract surgery, but most such cases can be successfully treated with NSAID or cortisone eye drops.
Until recently there were no good treatments for macular edema caused by central retinal vein occlusion (CRVO). Laser photocoagulation has been used for macular edema caused by branch retinal vein occlusion (BRVO).
Cystoid macular edema (CME) involves fluid accumulation in the outer plexiform layer secondary to abnormal perifoveal retinal capilary permeability. The edema is termed "cystoid" as it appears cystic; however, lacking an epithelial coating, it is not truly cystic. The etiology for CME can be remembered with the mnemonic "DEPRIVEN" (Diabetes, Epinepherine, Pars planitis, Retinitis pigmentosa, Irvine-Gass Syndrome, Venous occlusion, E2-prostaglandin, Nicotinic acid and Niacin).
Diabetic macular edema (DME) is similarly caused by leaking macular capillaries. DME is the most common cause of visual loss in both proliferative, and non-proliferative diabetic retinopathy.
In 2010 the US FDA approved the use of Lucentis injections for macular edema.
Iluvien, a sustained release intravitreal implant developed by Alimera Sciences, has been approved in Austria, Portugal and the U.K. for the treatment of vision impairment associated with chronic diabetic macular edema (DME) considered insufficiently responsive to available therapies. Additional EU country approvals are anticipated.