A pterygium is a non-cancerous growth of the clear, thin tissue (
Causes, incidence, and risk factors
The cause is unknown, but it is more common in people with excess outdoor exposure to sunlight and wind, such as those who work outdoors.
Risk factors are exposure to sunny, dusty, sandy, or windblown areas. Farmers, fishermen, and people living near the equator are often affected. Pterygium is rare in children.