Both a pterygium and pinguecula are abnormal growths that form on the surface of the eye. While they may appear similar, and have similar symptoms and causes, they are actually different conditions.
A pterygium (plural pterygia) is a wedge-shaped growth of abnormal conjunctival tissue that forms on the eye. While they are benign (non-cancerous) and relatively harmless, they extend onto the cornea (the clear front ‘window’ of the eye) where they may affect vision.
A pterygium can usually be seen as a fleshy, pink growth on the white of the eye, and may occur in one eye or both. They occur between the eyelids, most often in the corner of the eye, close to the nose, and extend onto the cornea.
Many people with a pterygium feel as if there is something in their eye. Symptoms also include dry eyes, irritation, inflammation and redness. They can also make it more difficult or uncomfortable to wear contact lenses.
If the pterygium extends onto the cornea far enough it can cause blurred vision as the curvature of the cornea is altered, and can also obscure vision.
The main cause is almost certainly lifetime sun exposure - UV light. People who live in hot, dry, sunny regions and spend a lot of time outdoors have a higher chance of developing a pterygium than others. The risk is also increased by not wearing sunglasses or a sun hat.
Sports people such as sailors, surfers and skiers also have a high incidence because of the high levels of reflected UV light they encounter. Pterygia are also more common in areas where there is ozone layer depletion.
Pterygia usually occur in people aged 20 to 50, and are more common in men, probably due to an increased likelihood of outdoor work environment.