The macula is the part of the retina that provides sharp central vision. Macular edema occurs when blood and other fluid leak into the macula, causing it to swell. The result is blurred and cloudy vision and, in extreme cases, a total loss of vision. There are two types of macular edema. Diabetic macular edema is a complication of diabetic retinopathy, where weak blood vessels leak into the retina. Cystic macular edema is a condition that often occurs soon after cataract surgery and implantation of an intraocular lens.