Red eye and conjunctivitis
Normal vision, no pain, no light sensitivity, normal pupil and no corneal staining? Then it's safe to call it conjunctivitis.
A 10-year-old boy has itchy, watery eyes every spring and summer, with stringy white discharge. When you evert his upper lids you see large "cobblestone" bumps. His mother has been buying steroid eye drops from the pharmacy whenever it flares, for 2 years.
A 6-day-old baby has swollen eyelids with thick yellow pus pouring out of both eyes.
What does each have, and what is the danger in each case?
- Serious featuresReduced vision, real pain, photophobia, abnormal pupil, contact lens wearer, trauma: eye team.
- Newborn with sticky or swollen eyesGonococcal or chlamydial conjunctivitis: urgent swabs and systemic treatment.
- BacterialSticky discharge, lids stuck in the morning: often self-limiting, chloramphenicol if severe.
- ViralWatery, gritty, recent cold, tender node in front of the ear: hygiene, lubricants. Very contagious.
- AllergicItch, both eyes, seasonal: antihistamine or mast cell stabiliser drops.
- Subconjunctival haemorrhagePainless red patch, normal vision: check BP, reassure.
- No steroid drops without an eye specialistGlaucoma, cataract, herpes keratitis.
- Reduced vision or pain
- Photophobia
- Contact lens wearer
- Newborn with sticky eyes
- Long-term steroid drop use
- Red eye with a fixed or irregular pupil
- Keratitis (bacterial, herpes, fungal)
- Uveitis (iritis)
- Acute angle-closure glaucoma
- Scleritis
- Neonatal gonococcal conjunctivitis
- Steroid-induced glaucoma
- Foreign body
| Chloramphenicol drops | 0.5%, 1 drop every 2 hours for 2 days, then 4 times daily, 5 days total |
| Chloramphenicol ointment | At night, or 3–4 times daily alone |
| Viral conjunctivitis | Contagious for about 2 weeks |
| Neonatal conjunctivitis | Within 28 days of birth: urgent |
| Gonococcal in newborns | Within the first days, profuse pus: IV or IM ceftriaxone, admit |
| Chlamydial in newborns | 5–14 days: oral azithromycin or erythromycin |
| Steroid drops | Only by an eye specialist |
Check every dose against a current drug reference and your hospital protocol.
On this page
Which red eye?
- Conjunctivitis
- treat by type
- Subconjunctival haemorrhage
- BP, reassure
- Keratitis, uveitis, glaucoma, scleritis
- same-day eye review
| Feature | Conjunctivitis | Keratitis | Uveitis | Acute glaucoma |
|---|---|---|---|---|
| Vision | Normal | Reduced | Reduced | Reduced |
| Pain | Gritty or itchy | Severe | Aching, photophobia | Severe, vomiting |
| Redness | Diffuse, more at the edges | Around the cornea | Around the cornea (ciliary flush) | Diffuse |
| Discharge | Yes | Watery or pus | Watery | Watery |
| Pupil | Normal | Normal or small | Small, irregular | Fixed, mid-dilated |
| Fluorescein | Normal | Staining (ulcer, dendrite) | Normal | Cloudy cornea |
Conjunctivitis by type
| Type | Features | Treatment |
|---|---|---|
| Bacterial | Sticky yellow discharge, lids stuck in the morning, both eyes | Clean lids; chloramphenicol if severe or not settling |
| Viral (adenovirus) | Watery, gritty, red, recent cold, tender preauricular node | Hygiene, lubricants, cool compresses; contagious 2 weeks |
| Allergic | Itch, both eyes, seasonal, other allergies | Antihistamine or mast cell stabiliser drops, oral antihistamine |
| Vernal keratoconjunctivitis | Boys, hot climates, itch, stringy discharge, cobblestones | Mast cell stabilisers, antihistamine drops; steroids only by eye specialist |
| Neonatal | Newborn within 28 days, sticky or swollen | Urgent swabs, systemic treatment |
| Trachoma | Repeated infections, lid scarring, in-turned lashes | Azithromycin, eye team; still seen in some rural areas |
Vernal keratoconjunctivitis in Pakistan
- Common in boys aged 5–15 in hot, dry climates; worse in spring and summer.
- Intense itch, stringy discharge, light sensitivity, cobblestone papillae under the upper lid, gelatinous nodules at the limbus.
- Treatment: cool compresses, mast cell stabiliser drops (sodium cromoglicate, olopatadine), antihistamine drops, avoid rubbing.
- Steroid drops are often bought over the counter. Long-term use causes glaucoma and cataract that can blind a child. Steroids only under an eye specialist, short courses, with pressure checks.
Neonatal conjunctivitis
- Gonococcal: days 1–5, profuse pus, swollen lids; can perforate the cornea within days. Swab, IV or IM ceftriaxone, admit, treat the mother and partner.
- Chlamydial: days 5–14, milder discharge; can cause pneumonia. Oral azithromycin or erythromycin; treat parents.
- Blocked tear duct: sticky eye without redness, common; massage and cleaning.
Treatment
Hygiene advice
- Wash hands often; don't share towels or pillows.
- Clean discharge with cooled boiled water and a clean cotton pad, wiping from the inside out.
- Avoid contact lenses until better.
Common mistakes
- Not checking visual acuity in a red eye.
- Calling keratitis "conjunctivitis" in a contact lens wearer.
- Unsupervised steroid drops (or allowing pharmacy steroid use to continue).
- Treating neonatal conjunctivitis with drops alone.
- Missing uveitis (photophobia, small pupil, ciliary flush).
Frequently asked questions
How do I treat conjunctivitis?
Most bacterial and viral conjunctivitis settles without treatment. Chloramphenicol drops for severe bacterial cases; antihistamine or mast cell stabiliser drops for allergic. Wash hands and don't share towels.
When is a red eye serious?
When vision is reduced, there is real pain or photophobia, the pupil is abnormal, the patient wears contact lenses, or there was trauma or a chemical.
Why are steroid eye drops dangerous?
Unsupervised use causes glaucoma, cataract and worsening of herpes and fungal infections.
Is a subconjunctival haemorrhage dangerous?
Usually not. It is painless with normal vision and clears in 2–3 weeks. Check BP and ask about anticoagulants or trauma.
Test yourself
Exam-style questions on this guide, from our two question banks. Choose an answer to see why each option is right or wrong.
1. A boy with seasonal itchy eyes and cobblestones under the upper lid uses pharmacy steroid drops. What is the risk?
Answer: Glaucoma. Vernal keratoconjunctivitis: use mast cell stabilisers and antihistamines; steroids only with an eye specialist.
- None: Steroid drops are risky.
- Myopia: No.
- Allergy: No.
- Dry eye only: Steroids cause more serious harm.
2. A contact lens wearer has a painful red eye and reduced vision. What is the most important concern?
Answer: Microbial keratitis. Same-day eye referral; stop lens wear.
- Dry eye: No.
- Viral conjunctivitis: Possible but keratitis is the danger.
- Subconjunctival haemorrhage: No.
- Allergic conjunctivitis: No.
3. A painless bright red patch appears on the white of the eye after coughing. Vision is normal. What is it?
Answer: Subconjunctival bleed. Reassure, check BP and anticoagulant use.
- Hyphaema: In the anterior chamber.
- Scleritis: Painful.
- Glaucoma: Painful.
- Conjunctivitis: Diffuse, discharge.
4. A farmer was hit in the eye by a crop leaf 10 days ago. He has a corneal ulcer with dry, raised, feathery margins, satellite lesions and a hypopyon; it worsened with steroid–antibiotic drops from a pharmacy. What is the likely cause and treatment?
Answer: Fungal keratitis — stop steroids, natamycin. Microbial keratitis is an ophthalmic emergency. Fungal keratitis is common in agricultural tropical regions after vegetative trauma (filamentous fungi — Fusarium, Aspergillus) and in immunocompromised/steroid users (Candida). Features: slower onset, dry raised greyish ulcer with feathery margins, satellite lesions, endothelial plaque, hypopyon; worsens with steroids. Diagnosis: corneal scraping — KOH/Gram stain, culture (Sabouraud). Treatment: topical natamycin 5% (filamentous) hourly, voriconazole/amphotericin as alternatives, stop steroids, cycloplegic; therapeutic keratoplasty if perforation. Bacterial (Pseudomonas in contact lens wearers, Staph, Strep pneumoniae): rapid, suppurative — fortified antibiotics or fluoroquinolone after scraping.
- Bacterial keratitis — continue steroids: Steroids worsen fungal keratitis, and feathery margins with satellites suggest fungus.
- HSV — oral aciclovir: HSV gives a dendritic ulcer, not feathery margins after plant trauma.
- Acanthamoeba: Acanthamoeba is linked to contact lenses and causes a ring infiltrate.
5. A man on warfarin wakes with a painless, bright red patch covering half of the white of one eye. Vision is normal, there is no discharge and the eye is comfortable. What is the diagnosis?
Answer: Subconjunctival haemorrhage. Subconjunctival haemorrhage: rupture of small conjunctival vessels → bright red, well-demarcated flat patch; painless, vision unaffected. Causes: spontaneous, Valsalva (coughing, vomiting, straining, lifting), minor trauma, contact lenses, hypertension, anticoagulants/antiplatelets, bleeding disorders, acute conjunctivitis (adenovirus, Haemophilus), pertussis in children. Management: reassure, lubricants for comfort; check BP and INR (on warfarin) or clotting screen if recurrent/bilateral; in trauma with no posterior limit to the haemorrhage, suspect orbital (base of skull/anterior cranial fossa) fracture and penetrating injury. It changes colour from red to yellow as it resolves over 1–2 weeks.
- Acute angle-closure glaucoma: Acute angle closure is painful, with reduced vision and a fixed mid-dilated pupil.
- Anterior uveitis: Uveitis is painful with photophobia and ciliary flush.
- Bacterial conjunctivitis: Bacterial conjunctivitis causes discharge and diffuse redness.
6. Touching the right cornea causes neither eye to blink. Touching the left cornea makes both eyes blink. Which nerve is damaged?
Answer: Right trigeminal (V1). The afferent limb of the corneal reflex is the ophthalmic division of the trigeminal nerve (via the nasociliary nerve), and the efferent limb is the facial nerve to orbicularis oculi on both sides. Touching the right cornea produces no blink on either side, so the right afferent (V1) is lost. Touching the left cornea produces blinking on both sides, so both facial nerves work. A facial nerve lesion would abolish blinking only on that side, whichever eye is touched.
- Right facial nerve: A right VII lesion would leave the left eye blinking when the right is touched.
- Left facial nerve: A left VII lesion would stop left blinking from either side.
- Right oculomotor nerve: III does not take part in the corneal reflex.
- Left trigeminal (V1): Touching the left cornea gave a normal reflex.
7. During brainstem death testing, the corneal reflex is absent on both sides. Which nerves form this reflex arc?
Answer: Trigeminal in, facial out. Touching the cornea stimulates the ophthalmic division of the trigeminal nerve (afferent). The signal passes through the pons to both facial nuclei, and the facial nerve closes both eyelids (efferent). Absent corneal reflexes, along with absent pupillary, oculocephalic, vestibulo-ocular, gag and cough reflexes and apnoea, are part of brainstem death testing. The pupillary reflex uses the optic and oculomotor nerves; the gag uses IX and X.
- Optic in, oculomotor out: That is the pupillary light reflex.
- Facial in, trigeminal out: Reversed.
- Trigeminal in, oculomotor out: Eyelid closure is by the facial nerve.
- Glossopharyngeal in, vagus out: That is the gag reflex.
References and dose sources
- NICE CKS — Conjunctivitis: infective
- NICE CKS — Red eye
- Chloramphenicol eye drops and ointment dosing: Drugs.com: Chloramphenicol ophthalmic (see also our chloramphenicol eye drops and ointment dose page)
- Cetirizine dosing: Drugs.com: Cetirizine dosage (see also our cetirizine dose page)
- Ceftriaxone dosing: Drugs.com: Ceftriaxone dosage (see also our ceftriaxone dose page)
International guidance is linked where it reflects good practice. Where your hospital’s protocol differs, follow your hospital.