Fundoscopy image of the retina of the left eye of a female patient who has a subluxated (partially dislocated) intraocular lens. An intraocular lens is an artificial lens that replaces the clear lens at the front of the eye. It is most often used to treat cataracts. The retina is the light-sensitive layer at the back of the eye. The subluxation of the lens is causing the optic disc (bright), which is where blood vessels and the optic nerve enter the retina, to appear doubled. Surgery is needed to reposition or replace the intraocular lens.