Ophthalmology & General Medicine
Conjunctivitis
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Conjunctivitis is an inflammation of the conjunctiva—a thin, transparent mucous membrane that lines the inner surface of the eyelids (palpebral conjunctiva) and covers the anterior surface of the sclera up to the corneoscleral limbus (bulbar conjunctiva). It is the most common eye condition in primary care, accounting for several million annual visits in Canada. Although often benign and self-limiting, conjunctivitis requires careful clinical evaluation because it is part of the differential diagnosis of red eye, which includes serious and potentially blinding eye conditions—keratitis (corneal inflammation), anterior uveitis (iritis), acute angle-closure glaucoma, and keratoconjunctivitis—which must be recognized and promptly referred to an ophthalmologist. The three main etiological forms are viral conjunctivitis (the most common, accounting for 65–80% of infectious conjunctivitis—primarily caused by adenoviruses), bacterial conjunctivitis (20–30%—primarily Staphylococcus aureus, Streptococcus pneumoniae, Haemophilus influenzae in children and Neisseria gonorrhoeae (in hyperacute forms) and allergic conjunctivitis (very common in the context of seasonal or perennial rhinoconjunctivitis). The clinical distinction between these three forms—though imperfect—guides treatment and the decision to prescribe topical antibiotics or not, thus avoiding excessive and unjustified use of antibiotics for viral conjunctivitis, which resolves spontaneously in 7 to 14 days.
Differential diagnosis of red eye — recognizing serious forms
| Diagnosis | Key distinguishing features | Emergency |
|---|---|---|
| Conjunctivitis (viral, bacterial, allergic) | Normal visual acuity; no intense photophobia; secretions (purulent, serous, or mucous); pruritus (allergic); no deep eye pain | Non-urgent |
| Keratitis (corneal disease) | Severe eye pain; marked photophobia; reflex tearing; possible reduced visual acuity; visible corneal opacity; context: contact lens wear, herpes, trauma | Urgent |
| Anterior uveitis (iritis) | Deep eye pain; intense photophobia; ciliary flush; blurred vision; irregular miotic pupil (synechiae); context: SpA, sarcoidosis, HLA-B27 | Urgent |
| Acute angle-closure glaucoma | Very intense eye pain + frontal headache; nausea/vomiting; blurred vision with colored halos; semi-dilated pupil, unresponsive; hard eyeball to the touch; very high intraocular pressure | Absolute emergency |
| Episcleritis / Scleritis | Episcleritis: localized sectoral redness, moderate discomfort, benign; Scleritis: intense and deep pain, diffuse violaceous hyperemia, systemic involvement (polyarthritis, Wegener's) | Variable |
| Conjunctival or corneal foreign body | Intense unilateral foreign body sensation; localized redness; tearing; examination of the upper palpebral conjunctiva after eyelid eversion | Consultation |
Viral conjunctivitis
- Pathogens: adenovirus (serotypes 3, 4, 7, 8, 19, 37) — by far the most common (accounting for 65–80% of infectious conjunctivitis cases); herpes simplex virus (HSV-1) — herpetic keratoconjunctivitis with corneal dendrites visible under a slit lamp, eyelid vesicles; Varicella-Zoster (ophthalmic zoster — trigeminal V1 — ophthalmological emergency); Enterovirus 70 and Coxsackievirus A24 — epidemic hemorrhagic conjunctivitis with very sudden onset; Adenovirus types 8, 19, and 37 — highly contagious epidemic keratoconjunctivitis (EKC) with corneal subepithelial infiltrates and preauricular lymphadenopathy
- Typical clinical presentation: unilateral onset with involvement of the second eye 1 to 5 days later; watery, clear (serous) discharge, rarely mucoid; diffuse conjunctival hyperemia with conjunctival follicles (small lymphoid protrusions visible on the inferior tarsal conjunctiva); moderate eyelid edema; profuse tearing; foreign body or gritty sensation; mild photophobia; palpable preauricular lymphadenopathy in 50–70% of cases (pathognomonic of adenoviral conjunctivitis); frequent epidemic context (affected contacts, community, seasonal outbreak)
- Evolution and duration: spontaneous resolution in 7 to 14 days in typical forms; epidemic keratoconjunctivitis can last 2 to 4 weeks with persistent subepithelial infiltrates affecting vision transiently; hypercontagious for up to 14 days - strict hand washing, avoid sharing towels and pillowcases, school exclusion according to local public health guidelines
- Treatment: No specific antiviral treatment for adenoviruses; symptomatic local care — preservative-free artificial tears (relieve dryness and dilute secretions), cold compresses (natural vasoconstrictor and antipruritic); topical antihistamines if significant inflammatory component; topical corticosteroids contraindicated without prior ophthalmological evaluation — risk of worsening an underlying herpetic keratitis; topical antivirals (acyclovir ophthalmic ointment) if confirmed or highly suspected herpetic kerato-conjunctivitis (eyelid vesicles, corneal dendrites)
Bacterial conjunctivitis
- Pathogen agents by age and context: infant (< 1 month) — Neisseria gonorrhoeae (J1–J4) and Chlamydia trachomatis (J5–J14) — Notifiable neonatal ophthalmies; preschool child — Haemophilus influenzae non-typable (most common in pediatrics), Streptococcus pneumoniae, Moraxella catarrhalis ; adult Staphylococcus aureus (most frequent), streptococci, H. influenzae ; young sexually active adult — to elicit Chlamydia trachomatis (inclusion conjunctivitis — unilateral, chronic, large conjunctival follicles, preauricular lymphadenopathy) and Neisseria gonorrhoeae (hyperacute form)
- Typical clinical presentation: unilateral or bilateral onset; purulent (yellow-greenish) or mucopurulent discharge — eyelids stuck together upon waking («eyes glued shut in the morning» — a very suggestive sign of bacterial vs. viral, where discharge is more watery); diffuse conjunctival hyperemia; eyelid edema; absence of preauricular adenopathy (unlike viral conjunctivitis); normal visual acuity; absence of intense photophobia
- Hyperacute gonococcal conjunctivitis — ophthalmologic emergency: very abundant purulent discharge (creamy, spurting upon opening the eyelids), sudden onset, significant eyelid swelling, frequent and rapid corneal involvement (corneal ulcer, perforation); young adult with a history or risk factors for STIs; imperative systemic treatment — ceftriaxone 1 g IM single dose + doxycycline (co-infection with Chlamydia) ; abundant discharge of secretions ; urgent ophthalmological opinion
- Topical antibiotic treatment: controversial indication — meta-analyses show that 60–65% of bacterial conjunctivitis cases resolve spontaneously within 5–7 days without antibiotics; topical antibiotics accelerate clinical and microbiological resolution by 2 to 3 days and reduce contagiousness; tobramycin 0.3% % (Tobrex) eye drops — 1 drop 6 times/day × 5–7 days — broad-spectrum, well-tolerated, first-line in North America; azithromycin 1.5% % (AzaSite) — 1 drop twice daily × 2 days then once daily × 5 days — good coverage, easy to adhere to; ciprofloxacin 0.3% % — alternative, particularly for contact lens wearers (coverage Pseudomonas; erythromycin ophthalmic ointment - first choice for newborns (chlamydial conjunctivitis); sulfacetamide - less used, frequent resistance; avoid aminoglycosides (gentamicin, neomycin) as first-line treatment in children due to conjunctival epithelial toxicity with prolonged use
Allergic conjunctivitis
- Clinical forms: Seasonal allergic rhinoconjunctivitis (SAR) - the most frequent; spring or summer onset coinciding with pollen season (birch, grasses, ragweed in the fall in Quebec); intense bilateral ocular itching (cardinal and pathognomonic symptom of allergic conjunctivitis); clear tearing; chemosis (conjunctival edema); diffuse hyperemia; associated rhinitis, sneezing, nasal congestion; Perennial allergic rhinoconjunctivitis (PAR) - exposure to indoor allergens (mites, animal dander, molds) - year-round symptoms with exacerbations; Vernal keratoconjunctivitis (VKC) - severe form in children and adolescents, predominant in hot countries; giant papillae ("cobblestone") on the upper tarsal conjunctiva; possible corneal involvement (corneal shield); Atopic keratoconjunctivitis (AKC) - severe atopic adult; Giant papillary conjunctivitis (GPC) related to contact lens deposits
- Topical antiallergic treatment — step-by-step approach: new-generation topical antihistamines — olopatadine 0.1% 1% (Patanol) 1 drop twice daily or 0.2% 1% (Pataday) 1 drop once daily; ketotifen 0.025% % (Zaditor) 1 drop twice daily — dual action as an antihistamine and mast cell stabilizer; topical azelastine; disodium cromoglycate 2% % eye drops — mast cell stabilizer, effective for prevention if used before allergen exposure; systemic oral antihistamines (cetirizine, loratadine, fexofenadine) — useful if allergic rhinitis is present but less effective than antihistamine eye drops for ocular symptoms; allergen avoidance (sunglasses, avoid rubbing eyes, shower upon returning home); subcutaneous or sublingual allergen immunotherapy — maintenance treatment for moderate to severe forms; topical corticosteroids (fluorometholone, loteprednol) — reserved for severe forms under ophthalmological prescription (risk of corticosteroid-induced glaucoma and cataracts with prolonged use)
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The most useful clinical rule of thumb: Intense bilateral itching = allergic ; preauricular adenopathy + watery secretions = viral ; Pus-filled secretions sticking eyelids together upon waking = bacterial. None of these signs is 100% pathognomonic for %, but the combination of the clinical context (age, history of atopic conditions, epidemiological context, sexual partners) and these three factors provides a reliable diagnostic guide in the vast majority of cases at the initial stage.
Neonatal conjunctivitis (ophthalmia neonatorum)
- Neisseria gonorrhoeae (J1–J4): Very abundant purulent secretions, major eyelid edema, risk of corneal ulcer and blindness without immediate treatment; transmission during passage through the infected birth canal; treatment: ceftriaxone 25–50 mg/kg IV or IM single dose + abundant saline eye irrigation; universal prevention at birth with erythromycin ointment or povidone-iodine recommended in many jurisdictions
- Chlamydia trachomatis (J5–J14): mucopurulent discharge, conjunctival hyperemia, eyelid edema; risk of infant chlamydial pneumonia if untreated; mandatory systemic treatment—erythromycin 12.5 mg/kg PO qid × 14 days (topical treatment alone is insufficient as chlamydia persists in the nasopharynx); screening and treatment of parents
- Chemical conjunctivitis of the newborn: within the first 24 hours — transient reaction to silver nitrate (old prophylaxis, almost abandoned); spontaneous resolution in 24–48 hours without treatment
Treatment — Practical Summary
| Type | Recommended Treatment | Duration / Notes |
|---|---|---|
| Viral (Adenovirus) | Local care: preservative-free artificial tears, cold compresses; no topical antibiotics (ineffective) | Resolution 7–14 days; isolation recommended 7–14 days |
| Bacterial (non-gonococcal) | Tobramycin 0.3% 1-3 times daily as eye drops 6 times a day, or azithromycin 1.5% 1-3 times daily 2 times a day; clean secretions with moist compresses | 5–7 days; treatment accelerates healing by 2–3 days |
| Gonococcal bacterium | Ceftriaxone 1 g IM single dose + doxycycline 100 mg × 7 days (chlamydia co-infection); eye drops + urgent ophthalmology consultation | Emergency — Risk of corneal perforation |
| À Chlamydia trachomatis | Doxycycline 100 mg twice a day for 7 days (adult); oral erythromycin for 14 days (infant); treat partner(s) | Mandatory systemic treatment — topical alone is insufficient |
| Seasonal allergies | Olopatadine 0.1% 1–3 times daily or ketotifen 0.025% 1–3 times daily, twice daily; oral antihistamines if rhinitis is present; artificial tears | During pollen season; allergen avoidance |
| Herpetic (HSV) | Acyclovir ophthalmic ointment 3 % 5 times daily; or trifluridine 1 % eye drops; consult an ophthalmologist | 7–14 days; absolute contraindication to topical corticosteroids |
Signs Requiring Urgent Ophthalmological Consultation
Consult a doctor or ophthalmologist without delay if the red eye is accompanied by intense eye pain (not just discomfort or a gritty sensation), a decrease in visual acuity, intense photophobia, an asymmetric or non-reactive pupil, visible corneal opacity, or if symptoms do not improve after 5 to 7 days of treatment. These signs may indicate keratitis, uveitis, acute glaucoma, or severe epidemic keratoconjunctivitis. In contact lens wearers with a red and painful eye, remove the lenses immediately and seek emergency care – risk of keratitis. Pseudomonas or Acanthamoeba that can threaten vision within 24 to 48 hours.
Consult at Clinique Omicron
Les médecins de Clinique Omicron diagnostiquent et traitent les conjonctivites virales, bactériennes et allergiques, prescrivent les collyres appropriés, dépistent les conjonctivites à chlamydia dans un contexte d'ITSS et orientent vers l'ophtalmologiste toute forme suspecte de kératite, d'uvéite ou de conjonctivite gonococcique. Des consultations sont disponibles dans nos succursales au Québec ainsi qu'en télémédecine pour l'ensemble de la province. Pour prendre rendez-vous, Choose your online service.
The content of this page is provided for informational purposes only and does not substitute for advice from a qualified healthcare professional. Any severe eye pain or vision loss associated with a red eye requires an urgent ophthalmological evaluation.
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