Pterygium is an abnormal growth of fibrovascular tissue on the eye's conjunctiva. It typically appears on the side near the nose but can affect both sides of the eye. 

Causes:

• Prolonged exposure to sunlight is the primary factor in pterygium development. However, other factors such as exposure to dust, dirt, heat, air, dryness, and smoke can also worsen an existing pterygium.

• Exposure of the eyes to industrial solvents and chemicals may also cause pterygium.
  
  

Common symptoms:

Redness of the eyes, tearing, the sensation of a foreign body in the eye, itching, blurred vision. 

Treatment:

In the early stages, it can be treated with artificial tears or anti-inflammatory eye drops. If the pterygium grows enough to cause problems, it can be surgically removed.