Conjunctivitis (Pink Eye)

Conjunctivitis is inflammation of the conjunctiva, the transparent mucous membrane covering the white of the eye and the inner eyelid. It is one of the most common ocular conditions worldwide. Etiologies include viral (most often adenovirus), bacterial (Staphylococcus, Streptococcus, Haemophilus, Pseudomonas, Neisseria gonorrhoeae, Chlamydia trachomatis), allergic and irritant/chemical causes.

Viral conjunctivitis is highly contagious and frequently bilateral with watery discharge, follicular reaction and preauricular lymphadenopathy. Bacterial conjunctivitis produces purulent discharge with eyelid sticking. Allergic conjunctivitis features intense itching, chemosis and bilateral involvement, often with seasonal allergic rhinitis. Hyperacute bacterial forms (gonococcal) are a medical emergency due to corneal perforation risk.

Differential diagnosis includes keratitis, uveitis, acute angle-closure glaucoma and dry eye disease. Red flags such as severe pain, photophobia, decreased vision or contact lens wear require urgent ophthalmology referral to exclude vision-threatening pathology.