Sight loss caused by macular degeneration. Street scene as it would appear to a patient with macular degeneration, or damage to the photoreceptive cells in the macula. The macula is a sensitive region of the retina with a high concentration of photoreceptors. Macular degeneration is usually age-related, and has two forms, dry and wet. Dry age-related macular degeneration (AMD) is caused by death of the photoreceptors and their supporting cells, and is currently untreatable. Wet AMD is caused by abnormal blood vessel growth underneath the macula. Haemorrhaging and leaking of the blood vessels damages the photoreceptors and leads to sight loss. The progress of this form of the disease can be slowed by drugs or laser surgery. For an image showing how someone with normal sight would view this scene, see P420/596.