A pterygium is a growth of the conjunctiva or mucous membrane that covers the white part of your eye over the cornea. The cornea is the clear front covering of the eye. This benign or noncancerous growth is often shaped like a wedge. A pterygium usually doesn’t cause problems or require treatment, but it can be removed if it interferes with your vision.
What causes it?
The exact cause of pterygium isn’t known. One explanation is that too much exposure to ultraviolet (UV) light can lead to these growths. It occurs more often in people who live in warm climates and spend a lot of time outdoors in sunny or windy environments. People whose eyes are exposed to certain elements on a regular basis have a higher risk of developing this condition. These elements include:
What are the symptoms?
A pterygium doesn’t always cause symptoms. When it does, the symptoms are usually mild. Common symptoms include redness, blurred vision, and eye irritation. You might also feel a burning sensation or itchiness. If a pterygium grows large enough to cover your cornea, it can interfere with your vision. Thick or larger pterygium can also cause you to feel like you have a foreign object in your eye. You might not be able to continue wearing contact lenses when you have a pterygium due to discomfort..
A chalazion is a painless bump on your eyelid. It can affect the upper or lower eyelid.
Chalazia (plural for chalazion) result from healed internal styes that no longer are infectious. These cyst-like eyelid bumps form around an oil gland within the lid and can cause red, swollen eyelids.
The contents of a chalazion include pus and blocked fatty secretions (lipids) that normally help lubricate the eye but can no longer drain out.
Many chalazia drain, resolving on their own. You can help this process along by applying warm compresses to your eyelid. Gently massaging the lid can help, too.
But some chalazia persist for more than several weeks and grow large enough to become cosmetically unappealing.
A large chalazion may press on the cornea, temporarily causing astigmatism and blurry vision.
What causes a chalazion?
It's often impossible to know what causes a chalazion. Risk factors include blepharitis and rosacea.
People with rosacea — characterized by facial redness and swollen bumps under the skin — are prone to have certain eye problems such as blepharitis and chalazia.
Rosacea can affect eyelids, the eye's thin outer membrane (conjunctiva), the clear eye surface (cornea) and the white of the eye (sclera).
Rosacea that affects the eye and surrounding tissues is called ocular rosacea.
Causes of rosacea itself can be difficult to pinpoint, although environment and inherited tendencies are likely factors. Certain microorganisms living in or near eyelash roots also may exacerbate inflammation around the eye.