A pterygium is a growth on the conjunctiva (white part of the eye) that extends and grows over the cornea (clear part of the eye). Pterygia are usually wedge shaped, and are typically caused by UV exposure. Certain conditions like chronic dry eye can also aggravate pterygia. Small pterygia can be asymptomatic, but often they can redness and discomfort of the eye. Larger pterygia can affect the vision by changing the shape of the cornea, and in some instances even grow over the visual axis. Smaller pterygia are usually maintained with eye drops, but larger pterygia may need to be removed with surgery.