Both a pterygium and a 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 different conditions.
A pterygium is a wedge-shaped growth of abnormal tissue that forms on the eye. While they are benign (non-cancerous) and relatively harmless, they can sometimes extend onto the cornea where they may affect vision.
The exact reason pterygia occur is not completely understood. However, long term exposure to ultraviolet sunlight and chronic irritation from dry conditions seem to contribute to their development. Pterygia are more common in people that live in tropical environments.
A pinguecula on the other hand, occurs only on the conjunctiva (the thin, protective membrane that covers the surface of the eye), and will not grow across the cornea.
Pingueculae are thought to be caused by exposure to ultra-violet radiation, wind and dust, and are common among people who spend a considerable amount of time outdoors, particularly in very sunny environments.
A pterygium can usually be seen as a fleshy, pink growth on the white of the eye, and may occur in one or both eyes. They occur between the eyelids, most often in the corner of the eye, close to the nose; but can sometimes extend onto the cornea.
Many people with a pterygium feel as if there is something in their eye. Pterygium 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 it can cause blurred vision as the curvature of the cornea is altered, or it can also obscure vision.
A pinguecula has very similar symptoms to a pterygium. It usually appears as a creamy-coloured, chalky growth on the white of the eye between the eyelids. A pinguecula will also normally occur in the corner of the eye, near the nose, and can affect one or both eyes.
Just like a pterygium, a pinguecula can cause irritation, as well as difficulty wearing contact lenses. However, a pinguecula cannot grow across the cornea and therefore will not affect vision.
Causes of pterygia
Environmental factors such as a warm climate, dust and UV light are thought to be the main causes of pterygia. 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.
Skiers also have a high incidence of pterygia because of the high levels of reflected UV light they encounter. Pterygia are also more common in areas where there is ozone layer depletion and in people who work in dirty, dusty environments.
Pterygia usually occur in people aged 20 to 50, and are more common in men. However, it could be that their association with dirty, dusty environments accounts for the higher incidence in men.
Causes of pingueculae
Just like pterygia, pingueculae generally occur between the ages of 20 and 50. They are also thought to be caused by environmental factors such as the climate, dust and UV light.
Treating a pterygium or pinguecula
There are a number of different treatments for a pterygium or pinguecula. Normally, pterygium surgery will only be undertaken if the pterygium has severe symptoms or is affecting vision. Otherwise, management with eye drops is usually recommended.
Pingueculae are rarely surgically removed and are usually treated with eye drops. However, if the pinguecula turns into a pterygium, surgery may be the best course.