A pterygium is a raised growth in the surface of the eye (the conjunctiva) made mostly of collagen and tiny red capillaries. They are usually caused by extended exposure to sunlight. They may remain stable after appearing, or they may grow and affect vision.
Treatments include eye drops for irritation and redness, protection from sunlight and dust to prevent the pterygium from worsening, and occasionally steroids to lessen inflammation.
If the pterygium grows into the central cornea, surgical removal is recommended. This prevents the pterygium from altering the cornea's shape and affecting vision.