Pterygium

A pterygium is a raised growth that forms on the front surface of the eye.    A very early pterygium is an area of redness and thickening of the conjunctiva, the thin clear layer of skin over the front of the white part of the eye.  As it grows the pterygium creeps across the cornea, the clear front part of the eye.
Pterygia are caused by ultra violet light damage.  Dry dusty environments and allergies, can inflame them causing discomfort and redness.
If a pterygium grows big enough it distorts the front of the eye, causing changes to your prescription and vision.
 
If you have a pterygium the first step in treatment is artificial tear drops to improve comfort, and sunglasses to block further UV exposure.
If it is very uncomfortable, or is affecting the vision the pterygium can be removed surgically using a small graft to improve healing and limit the chance of regrowth.