Pink eye, also known as conjunctivitis, is primarily caused by inflammation of the conjunctiva, the membrane covering the white part of the eye and the inside of the eyelids. The main causes of pink eye include:
- Viral infections: The most common cause, often due to adenoviruses, which can be associated with respiratory infections like the common cold. Viral conjunctivitis is highly contagious and can spread easily through contact with infected eye secretions or respiratory droplets
- Bacterial infections: Caused by various bacteria such as Staphylococcus aureus, Haemophilus influenzae, and Streptococcus pneumoniae. Bacterial conjunctivitis is also contagious and can spread through direct contact or contaminated objects
- Allergic reactions: Triggered by allergens like pollen, pet dander, mold, dust mites, or cosmetics. Allergic conjunctivitis affects both eyes, is not contagious, and is often seasonal or related to environmental exposure
- Irritants: Exposure to chemicals, smoke, chlorine in swimming pools, or foreign objects in the eye can cause conjunctivitis. This type is not contagious and usually resolves once the irritant is removed
- Other causes: In newborns, an incompletely opened tear duct can cause pink eye
In summary, pink eye can be caused by viruses, bacteria, allergens, or irritants, with viral and bacterial forms being contagious, while allergic and irritant causes are not
