Macular degeneration refers to a condition caused by the macular area under the eye. In general, the macula is a normal physiologic structure at the bottom of the eye, and diseases caused by the macula are called macular degeneration. Macular degeneration is a very large category that typically includes many diseases, such as central plasma retinitis choroidopathy, which is often seen in young people. Middle-aged people often suffer from macular edema caused by retinal vein occlusion, or neovascularization of the macula. In older adults, diabetic retinopathy due to diabetes mellitus, or age-related macular degeneration causing hemorrhage, edema, or neovascularization. These conditions generally lead to macular disease, but treatment depends on the type of disease. For example, macular edema may require injections, and if it is causing hemorrhage, vitreous surgery may be needed to remove it completely.