Bacterial conjunctivitis

• Preauricular adenopathy is occasional; chemosis (thickened, boggy conjunctiva) is common.

• Discharge amount is copious; discharge quality is thick and purulent; conjunctival injection is moderate or marked.

Viral conjunctivitis

• Preauricular adenopathy is common in EKC and herpes; chemosis is variable.

• Discharge amount is moderate, stringy or sparse; discharge quality is thin and seropurulent; conjunctival injection is moderate or marked.

Chlamydial conjunctivitis tends to be chronic with exacerbation and remission

• Preauricular adenopathy is occasional; chemosis is rare;

• Discharge amount is minimal; discharge quality is seropurulent; conjunctival injection is moderate.

Allergic conjunctivitis occurs with itching as the hallmark symptom.

• Preauricular adenopathy is absent; chemosis is common.

• Discharge amount is moderate, stringy or sparse; discharge quality is clear; conjunctival injection is moderate.

Marginal ulcers (small white ulcers that appear on the cornea at the limbus) may indicate an allergic reaction to staphylococcal antigen.

• This is a toxin-related complication of Staphylococcus species that frequently causes blepharitis.

• Pain, photophobia, and a foreign body sensation are common. The ulcers are sterile and respond to topical steroids.

Bilateral disease typically is infectious or allergic.

Unilateral disease suggests toxic, chemical, mechanical, or lacrimal origin.

• Intraocular pressure is normal. Pupil size is normal. Light response is normal.

• Ciliary flush, corneal staining, and anterior chamber reaction is absent unless is a significant amount of keratitis is associated as seen in EKC.