Approach to the red eye

What it is

Conjunctivitis is a common red eye, and it separates into viral, bacterial and allergic forms, with chlamydial disease apart in neonates and in sexually active adults.

Causes and risk

The adenovirus is the most common agent causing viral conjunctivitis. The common bacterial agents are S. aureus, S. pneumoniae, H. influenzae and M. catarrhalis; in neonates, or in the sexually active, N. gonorrhoeae must be considered, which invades the cornea to cause keratitis, and C. trachomatis is the most common cause in neonates, and also causes trachoma and inclusion conjunctivitis.

The allergic forms divide by their cause. The atopic form is associated with rhinitis, asthma, dermatitis and hay fever, and one page calls it seasonal, from pollen, grasses and plant allergens. Another page names four instead, seasonal allergic conjunctivitis, vernal keratoconjunctivitis, atopic keratoconjunctivitis and giant papillary conjunctivitis, and calls atopic keratoconjunctivitis a severe ocular allergic disease, typically also involving the lids or other non ocular structures, usually perennial but able to worsen in winter months and often accompanied by atopic dermatitis. Vernal keratoconjunctivitis is called there a severe inflammatory disease that usually has seasonal recurrence. Giant papillary conjunctivitis is an immune reaction to mucus debris on lenses in contact lens wearers, caused by repeated mechanical irritation, and it is not a true ocular allergic reaction as the others are. Vernal conjunctivitis is seasonal, in warm weather, occurs in children and lasts for 5-10 yr then resolves.