Wet-macular degeneration may develop in patients with the dry form of macular degeneration. In the wet form, blood vessels that are leaky and abnormal begin to grow into the retina. Unlike normal blood vessels in the rest of the body, those seen in wet-macular degeneration cause swelling or bleeding into the retina. Wet-macular degeneration may cause either sudden or gradual loss of vision as these vessels leak fluid or bleed. If untreated, vision loss can progress.