A pinguecula is a raised yellowish white growth next to, but not overlapping, the cornea (the clear layer in front of the iris and pupil). This growth can be unsightly, but it typically does not cause any significant problems and does not need to be removed.
A pterygium is a fleshy growth of the conjunctiva next to the cornea that spreads across on to the cornea. Most pterygia do not cause symptoms, but sometimes they cause irritation or distort the shape of the cornea, possibly causing a change in vision. Sometimes removal is appropriate to reduce irritation and to correct changes in vision.
Last full review/revision November 2012 by Melvin I. Roat, MD, FACS