A pterygium is an ingrowth of tissue and blood vessels from the area over the white of the eye onto the clear corneal layer at the front of the eye. Pterygiums are thought to occur more frequently in eyes with a history of high levels of sun exposure, and those exposed to hot dusty environments.
Pterygiums can result in eye irritation, redness, and dryness. They are usually slow growing. Modern treatment by surgical removal has high success rates and is best performed before the pterygium becomes large. Large pterygiums can begin to distort the corneal surface and lead to blurred vision, the development of astigmatism, and permanent scarring.