Conjunctivitis, commonly known as “Pink eye”, is basically what medically refers to any sort of inflammation of the conjunctiva of the eye. The conjunctiva is the outer, wet surface of the eye and the inner surface of the eyelids.
There are three main causes of conjunctivitis:
Allergic conjunctivitis occurs due to allergy. The cause of these can be different for everyone; from pollen, to dust or even some chemicals you find in make-up!
You’ll often find you also have a runny nose (allergic rhinitis) if you’re prone to allergies. That itching and tearing eye, and the running nose is caused by histamine: something your body releases in reaction to the allergen. It also causes the small blood vessels to swell out, and this can cause a blocked-up feeling in your nose.
Viral or bacterial conjunctivitis are usually experienced together with a chest infection. Usually it starts in one eye first and then spreads to the other. Which viruses cause this infection? It can be some of the general respiratory (lung infection) viruses, but also Herpes simplex and Varicella zoster.
Bacterial conjunctivitis is always due to pyogenic (pus-producing) bacteria.
The most common bacteria include Staphylococci and Streptococci species.
Chemical conjunctivitis is due to exposure of the eyes to specific chemicals like acidic or alkali substances.
The most common and obvious symptom is a red eye or eyes.
Viral conjunctivitis is usually a general, fine redness of the white of the eye.
Allergic conjunctivitis will look similar to the viral type, but you usually have itchy eyes – rather than burning, painful eyes – and more tears than with the viral conjunctivitis.
Bacterial conjunctivitis will also have the redness, but the eyelids will be more swollen, and there can be a sticky yellow discharge from the eye.
This pus can make the lids to stick together especially after sleeping all night. Patients complain about an uncomfortable scratchy sensation in the eye and often that it is painful.
All of these will cause sensitivity to direct light and maybe also mildly blurred vision.
Viral and especially bacterial conjunctivitis is extremely contagious but can only spread by contact with the infected eye of another, so try and stay away from someone with pink eye, and – if you have pink eye – stay at home!