Pterygium on a patient's eye. This is a noncancerous growth that develops on the white of the eye. Initially, it may not cause any symptoms, but as it grows, the eye may become red, itchy, and a pink growth may appear. When it crosses over the cornea, it can cause blurry vision by warping the cornea, resulting in astigmatism. In severe cases, it may obscure vision by covering the cornea entirely. Pterygiums are more common in people who spend most of their time outdoors and tend to occur with increasing age. Pterygium can be successfully treated with surgery.