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Conjunctivitis

Conjunctivitis causes a red eye without reduced vision and without significant pain; the type is set by the discharge and the reaction — watery with follicles and a preauricular node in viral, purulent with papillae in bacterial, and itch with papillae in allergic — and any reduced vision, pain, photophobia or contact lens wear means something else until proven otherwise.

לקריאה בעברית

Why it matters in the exam

Viral (adenovirus) — the commonest: one eye and then the other, watery discharge, follicles, a preauricular lymph node, sometimes with sore throat and fever; highly contagious for 10–14 days. Treatment is supportive — cool compresses and tears — and hygiene; antibiotics do not help. Epidemic keratoconjunctivitis leaves subepithelial corneal infiltrates that cause prolonged blur, and only then is a steroid considered. Bacterial — purulent discharge and stuck lashes, treated with broad-spectrum antibiotic drops; in a contact lens wearer — cover Pseudomonas. Very acute conjunctivitis with profuse discharge — gonorrhoea: systemic ceftriaxone, because it penetrates the cornea.

Chlamydia in an adult — chronic follicular conjunctivitis of weeks that does not respond to drops, usually with genital infection; oral treatment (azithromycin or doxycycline) and testing of partners. Allergic — itch is the decisive sign, both eyes, swelling and papillae; dual-action drops (antihistamine and mast cell stabiliser, such as olopatadine). Vernal keratoconjunctivitis — a young boy in a warm climate, giant "cobblestone" papillae on the upper lid, Trantas dots and a corneal "shield" ulcer; atopic keratoconjunctivitis — an adult with eczema, with scarring and a risk of keratoconus. Granulomas with nodes (Parinaud oculoglandular) — Bartonella.

Conjunctivitis in the newborn — timing points to the cause: chemical on the first day; gonorrhoea on days 2–5 — profuse discharge and swelling, risk of perforation, treated with a single dose of ceftriaxone, intravenous or intramuscular, and testing for Chlamydia; Chlamydia on days 5–14 — oral treatment (erythromycin or azithromycin), because drops do not treat respiratory infection (pneumonia); HSV in weeks 1–2 — vesicles, intravenous acyclovir. Prevention at birth: erythromycin ointment. Trachoma, from Chlamydia trachomatis, is the leading infectious cause of blindness in the world; the World Health Organization works by the SAFE strategy.

Key points

• Red eye without reduced vision and without significant pain.
• Viral: watery, follicles, node; supportive treatment.
• Bacterial: purulent; gonorrhoea → ceftriaxone.
• Allergic: itch; dual-action drops.
• Newborn: gonorrhoea days 2–5, Chlamydia days 5–14.

Summary table

In the full version for subscribers

• A simple algorithm
• Memory aid
• Exam traps
• 5 review cards
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Sources

• AAO Preferred Practice Pattern: Conjunctivitis, 2018 — Viral, bacterial, allergic and neonatal conjunctivitis
• CDC Sexually Transmitted Infections Treatment Guidelines, 2021 — Ophthalmia neonatorum
• AAO Basic and Clinical Science Course, Section 8: External Disease and Cornea, 2024-2025 — Infectious and allergic conjunctivitis

Sources are given for further reading; the text is written afresh and not copied from them.

Reviewed by the Examqo AI Professor · 2026-11-06. The text may contain errors; when in doubt, check the source.