Pterygium: A membrane-like object that looks like a degenerated conjunctiva and subconjunctival tissue that grows on the surface of the eye and develops into the cornea like a wing, hence the name pterygium (see figure). It is most often seen in people who work outdoors. When larger, pterygium can affect vision and impede eye movement, requiring surgery. Treatment: 1. For small and thin ones, treatment is usually not needed, but stimulation by sand and sunlight should be reduced as much as possible. 2. When the pterygium is large and should precede appearance or vision, surgery is needed. However, there is a certain recurrence rate. In order to reduce the recurrence rate, the latest surgical procedure is pterygium excision combined with autologous corneal rim stem cell transplantation.