Conjunctivitis

Inflammation of the conjunctiva: viral (most common, adenovirus, highly contagious), bacterial (Staph, Strep pneumoniae, H. influenzae; gonococcal/chlamydial in neonates/sexually active adults), or allergic (seasonal/perennial).

• Viral: watery discharge, often bilateral, follicular reaction, preauricular lymphadenopathy, associated URTI, highly contagious

• Bacterial: purulent/mucopurulent discharge, lids stuck together on waking

• Allergic: bilateral itching (hallmark), watery discharge, chemosis, associated allergic rhinitis

• Neonatal (ophthalmia neonatorum): gonococcal (day 2-5, severe, sight-threatening) vs. chlamydial (day 5-14, more indolent) ; both urgent

Red flags (urgent ophthalmology): reduced visual acuity, significant pain, photophobia, corneal involvement, unilateral in contact lens wearer, trauma history, neonatal presentation.

Clinical, based on discharge pattern.

Swab for culture/PCR if severe, neonatal, recurrent, or refractory.

Fluorescein staining if pain/photophobia (exclude dendritic ulcer/keratitis).

Differentials: keratitis, episcleritis/scleritis, uveitis, dry eye, blepharitis, foreign body, angle-closure glaucoma.

• Viral: supportive (cool compresses, lubricants), self-limiting 1-3 weeks, hygiene advice given contagiousness, no antibiotics

• Bacterial: often self-limiting; topical chloramphenicol 0.5% drops or 1% ointment qds × 5-7 days speeds resolution/reduces transmission

• Allergic: topical antihistamine/mast cell stabilizer (olopatadine bd), oral antihistamines, cold compresses, allergen avoidance

• Gonococcal: same-day ophthalmology + systemic ceftriaxone; emergency given perforation risk; neonatal cases require admission, treat mother/partner

• Chlamydial: oral azithromycin (adults), erythromycin (neonates), treat as STI (partner treatment, STI screening)

• Contact lens wearers with pain: stop lens wear, low threshold for referral (exclude microbial keratitis)

Referral: ophthalmology for red flags, same-day for neonatal/gonococcal, non-resolving/recurrent disease.