Ophthalmology: Red emergencies

• Approach: Assessing a Red Eye | Red Flags — Refer Today
• Usually not sight-threatening: Bacterial Conjunctivitis | Viral Conjunctivitis | Allergic Conjunctivitis | Subconjunctival Haemorrhage | Episcleritis
• Sight-threatening: Scleritis | Anterior Uveitis | Acute Angle-Closure Glaucoma | Bacterial Keratitis and Contact Lens Ulcers | Herpes Simplex Keratitis | Herpes Zoster Ophthalmicus | Endophthalmitis | Preseptal and Orbital Cellulitis | Neonatal Conjunctivitis
• Eye injuries: Corneal Abrasion and Foreign Body | Chemical Injury | Blunt Trauma and Blowout Fracture | Penetrating Injury
• Revision: Drug Reference Table | Spot the Emergency | Exam-style Scenarios | Key Points | Guidelines and Further Reading

👁️ The red eye is one of the commonest eye presentations. Most cases are conjunctivitis or a harmless subconjunctival haemorrhage — but a few (acute glaucoma, keratitis, uveitis, scleritis, chemical injury, orbital cellulitis) can cause blindness within hours or days. Three questions sort most cases: Is vision reduced? Is there real pain or photophobia? Is the pupil abnormal? A "yes" to any means same-day eye casualty.
Your four questions for every patient: Is visual acuity reduced? Is it painful (not just gritty), with light sensitivity? Is the cornea clear and the pupil normal? Is there contact lens wear, trauma or a chemical?

Assessing a Red Eye

• Where is the redness?
  • Diffuse, including the inside of the lids — conjunctivitis.
  • Around the cornea (ciliary flush) — keratitis, uveitis, acute glaucoma.
  • Sectoral — episcleritis, scleritis.
• Always: Acuity, pupils, fluorescein, and ophthalmoscopy (or red reflex).

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Red Flags — Refer Today

• Reduced visual acuity.
• Moderate to severe pain (not just grittiness), or pain that wakes the patient.
• Photophobia.
• Abnormal pupil — fixed, irregular or mid-dilated.
• Corneal opacity or ulcer (fluorescein staining).
• Contact lens wearer with a painful red eye.
• Chemical injury — irrigate first, then refer.
• Penetrating or high-velocity injury.
• Recent eye surgery.
• Herpes zoster involving the eye or the tip of the nose.
• Neonate with red, sticky eyes.
• Proptosis or restricted, painful eye movements.

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Bacterial Conjunctivitis

• Features:
  • Red, gritty eye with sticky, purulent discharge; lids stuck together in the morning.
  • Often starts in one eye and spreads to both.
  • Normal vision, normal pupils, clear cornea.
• Organisms: Staphylococcus, Streptococcus pneumoniae, Haemophilus.
• Management (NICE CKS):
  • Usually self-limiting within 5–7 days.
  • Clean lids with cooled boiled water.
  • Chloramphenicol drops (0.5%, every 2 hours for 2 days then four times daily) or 1% ointment — if severe or not settling; or a back-up prescription. Fusidic acid as an alternative.
  • Children don't need to stay off school.
  • Contact lenses — stop wearing until resolved.
• Hyperacute (copious pus, rapid onset) — think gonococcal: urgent referral (corneal perforation risk), swab, systemic antibiotics, sexual health review.
• Chlamydial — chronic (weeks), follicular conjunctivitis in young sexually active adults; oral doxycycline or azithromycin; sexual health screen.

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Viral Conjunctivitis

• The commonest cause — usually adenovirus; very contagious.
• Features:
  • Red, gritty, watery eye; often both eyes.
  • Recent cold or sore throat.
  • Tender pre-auricular lymph node.
  • Follicles on the inner lid.
  • Can last 2–3 weeks.
• Management:
  • Cool compresses, lubricants.
  • Hygiene — hand washing, don't share towels.
  • No antibiotics.
  • Refer if vision falls or there is pain or photophobia (keratitis — small corneal spots).

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Allergic Conjunctivitis

• Features:
  • Itchy, red, watery eyes, both sides.
  • Swollen conjunctiva (chemosis) and lids.
  • Hay fever, eczema, asthma; seasonal (pollen) or year-round (dust mite, pets).
• Management:
  • Avoid triggers; cold compresses; don't rub.
  • Antihistamine drops (olopatadine, antazoline) or mast cell stabilisers (sodium cromoglicate — takes days to work).
  • Oral antihistamines.
• Vernal keratoconjunctivitis — severe allergic disease in boys with atopy: giant "cobblestone" papillae under the upper lid; can damage the cornea — refer.

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Subconjunctival Haemorrhage

• Features: A bright red, flat patch on the white of the eye with a clear edge; painless; vision normal. Often noticed by others.
• Causes:
  • Spontaneous (most); coughing, straining, vomiting.
  • Hypertension.
  • Anticoagulants and antiplatelets.
  • Minor trauma or rubbing.
  • Bleeding disorders (if recurrent).
• Management:
  • Reassure — fades over 1–3 weeks (goes yellow like a bruise).
  • Check BP; check INR if on warfarin.
  • Refer if after significant trauma (can't see its back edge — possible orbital or skull base fracture), recurrent, or with other bleeding.

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Episcleritis

• What it is: Inflammation of the thin layer above the sclera. Benign and self-limiting.
• Features:
  • Sectoral redness (a wedge), mild discomfort, no real pain.
  • Vision normal.
  • Red vessels move over the sclera and blanch with phenylephrine drops (scleral vessels don't).
• Associations: Usually none; sometimes rheumatoid arthritis, IBD.
• Management: Reassurance, lubricants, cool compresses; oral NSAID if uncomfortable. Settles in 1–3 weeks. Refer if severe pain (consider scleritis) or recurrent.

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Scleritis

• What it is: Inflammation of the sclera itself — can be sight-threatening and is often linked to systemic disease.
• Features:
  • Severe, deep, boring pain that radiates to the head and face and wakes the patient at night.
  • Tender globe; deep red or purplish redness that doesn't blanch with phenylephrine.
  • Reduced vision in severe or posterior scleritis.
  • Scleromalacia perforans — painless thinning in long-standing rheumatoid arthritis (sclera turns blue-grey).
• Associations (about half):
  • Rheumatoid arthritis (the commonest).
  • ANCA vasculitis (GPA).
  • Lupus, relapsing polychondritis, IBD.
  • Infection (herpes zoster, after surgery).
• Management:
  • Same-day ophthalmology.
  • Screen for systemic disease (ANCA, rheumatoid factor, anti-CCP, ANA, CRP, urine dip).
  • Oral NSAIDs for mild disease; systemic steroids and immunosuppressants (methotrexate, rituximab) for severe disease.

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Anterior Uveitis

• What it is: Inflammation of the iris and ciliary body (iritis).
• Features:
  • Pain (dull ache), photophobia, red eye with ciliary flush (redness around the cornea).
  • Blurred vision; watering (not sticky).
  • Small, irregular pupil (the iris sticks to the lens — posterior synechiae).
  • Cells and flare in the anterior chamber on slit lamp; hypopyon (layer of pus) in severe cases.
  • Usually one eye; often recurrent.
• Associations:
  • HLA-B27 disease — ankylosing spondylitis (axial spondyloarthritis), reactive arthritis, psoriatic arthritis, IBD.
  • Sarcoidosis.
  • Behçet's disease (hypopyon).
  • Juvenile idiopathic arthritis (children — silent, needs screening).
  • Herpes viruses; syphilis; TB.
  • Drugs — checkpoint inhibitors, bisphosphonates.
• Management:
  • Same-day eye casualty.
  • Steroid drops (e.g. prednisolone acetate 1% hourly, then tapered over weeks).
  • Dilating drops (cyclopentolate) — relieve pain and stop the iris sticking.
  • Monitor pressure.
  • Investigate recurrent or bilateral disease; ask about back pain (refer to rheumatology).
• Intermediate and posterior uveitis — floaters and blurred vision with little redness; sarcoid, MS, toxoplasmosis, CMV (HIV), Behçet's.

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Acute Angle-Closure Glaucoma

• What it is: The iris suddenly blocks the drainage angle; eye pressure shoots up (often 50–70 mmHg). It can cause permanent blindness within hours.
• Who: Older, long-sighted people, women, East Asian ancestry. Often triggered in dim light (evening) or by dilating drugs (anticholinergics, sympathomimetics, dilating drops, topiramate).
• Features:
  • Severe eye pain and headache.
  • Nausea and vomiting — may be mistaken for a GI or neurological problem.
  • Blurred vision, haloes around lights.
  • Red eye; hazy cornea.
  • Fixed, mid-dilated pupil (often oval).
  • Rock-hard eye to gentle palpation through the lid.
• Emergency treatment (while arranging immediate ophthalmology review):
  • Lie the patient flat (supine, face up) — lets the lens fall back.
  • Acetazolamide 500 mg IV (or orally if IV not possible) — reduces aqueous production. Avoid in sulfonamide allergy; caution in kidney disease and sickle cell.
  • Pressure-lowering drops — timolol 0.5%, apraclonidine or brimonidine.
  • Pilocarpine 1–2% — constricts the pupil to pull the iris out of the angle (works better once pressure starts to fall).
  • Steroid drops to reduce inflammation (specialist).
  • Analgesia and antiemetics.
  • IV mannitol if pressure won't come down (specialist).
• Definitive treatment: Laser peripheral iridotomy in both eyes (the other eye is at high risk), or lens extraction.

⚠️ Safety Pearl: An older person with headache, vomiting and a red eye may be sent for a CT head — look at the eye first. A fixed mid-dilated pupil and a hazy cornea point to acute glaucoma.

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Bacterial Keratitis and Contact Lens Ulcers

• What it is: Infection of the cornea — a sight-threatening emergency (scarring, perforation).
• Risk factors:
  • Contact lens wear — the biggest; especially sleeping in lenses, poor hygiene, swimming.
  • Corneal trauma; dry eye; exposure (facial palsy); steroid drops.
• Features:
  • Pain, photophobia, watering or discharge.
  • Reduced vision.
  • White spot (infiltrate) on the cornea that stains with fluorescein; ciliary flush; sometimes hypopyon.
• Organisms: Pseudomonas (contact lenses — fast and destructive), Staphylococcus, Streptococcus.
• Management:
  • Same-day eye casualty — don't treat in general practice.
  • Remove contact lenses; send the lenses and case for culture.
  • Corneal scrape for culture.
  • Intensive antibiotic drops — e.g. a fluoroquinolone (levofloxacin, ofloxacin) hourly day and night at first.
• Acanthamoeba keratitis — contact lenses rinsed in tap water or worn swimming; pain out of proportion to signs; ring infiltrate. Slow, hard to treat (specialist biguanide drops).
• Fungal keratitis — after plant or vegetable matter injury (gardening, farming).
• Contact lens wearer with a red painful eye — always refer the same day.

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Herpes Simplex Keratitis

• What it is: Reactivation of herpes simplex virus (HSV-1) in the cornea; a leading infectious cause of corneal blindness.
• Features:
  • Red, painful, watery eye; photophobia; blurred vision.
  • Often a history of cold sores or previous episodes.
  • Dendritic (branching) ulcer with fluorescein — diagnostic.
  • Reduced corneal sensation.
• Management:
  • Same-day ophthalmology.
  • Topical antiviral — ganciclovir 0.15% gel five times daily, or aciclovir 3% ointment; oral aciclovir in some cases.
  • Never give steroid drops for an active dendritic ulcer (they make it spread — a "geographic" ulcer).
  • Recurrent disease — long-term oral aciclovir prophylaxis.
• Stromal keratitis (deeper, immune-mediated) — specialists do use steroids with antiviral cover.

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Herpes Zoster Ophthalmicus

• What it is: Shingles in the ophthalmic division of the trigeminal nerve (V1) — forehead, upper lid, scalp.
• Hutchinson's sign — vesicles on the tip or side of the nose (nasociliary nerve) strongly predict eye involvement.
• Eye complications: Conjunctivitis, keratitis, uveitis, scleritis, raised pressure, optic neuritis, cranial nerve palsies; later corneal scarring and post-herpetic neuralgia.
• Management:
  • Oral antiviral within 72 hours of rash onset (or later if new lesions are still appearing) — aciclovir 800 mg five times daily or valaciclovir 1 g three times daily for 7 days.
  • Same-day ophthalmology if the eye is red, vision is reduced, or Hutchinson's sign is present; otherwise urgent review.
  • IV aciclovir if immunocompromised or severe.
  • Analgesia; consider early neuropathic pain treatment.
• Prevention — shingles vaccine (Shingrix) offered on the NHS to older adults and immunosuppressed people.

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Endophthalmitis

• What it is: Infection inside the eye — a sight-threatening emergency.
• Causes:
  • After eye surgery (cataract — usually within days to 2 weeks) or intravitreal injections (anti-VEGF).
  • Penetrating trauma.
  • Endogenous — spread from the blood: endocarditis, Candida (IV drug use, long-term lines, TPN), liver abscess (Klebsiella), immunosuppression.
• Features:
  • Pain, red eye, falling vision.
  • Hypopyon; poor red reflex.
• Management:
  • Immediate ophthalmology.
  • Vitreous tap for culture and intravitreal antibiotics (e.g. vancomycin and ceftazidime); sometimes vitrectomy.
  • Endogenous — blood cultures, echo, systemic treatment of the source; check the eyes of any patient with Candida bloodstream infection.

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Preseptal and Orbital Cellulitis

• Causes:
  • Orbital — usually spread from ethmoid sinusitis (especially children).
  • Preseptal — skin injury, insect bite, stye, sinusitis.
• Management:
  • Preseptal (mild, adults or older children) — oral co-amoxiclav; review within 24–48 hours. Admit young children.
  • Orbital — emergency:
    • Admit; IV antibiotics (e.g. ceftriaxone with metronidazole, or co-amoxiclav, per local policy).
    • CT of the orbits and sinuses with contrast.
    • Joint ophthalmology and ENT review.
    • Monitor vision, colour vision and pupils regularly.
    • Surgical drainage for subperiosteal or orbital abscess.
• Complications of orbital cellulitis: Vision loss, cavernous sinus thrombosis (bilateral signs, cranial nerve palsies), meningitis, brain abscess.

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Neonatal Conjunctivitis

• Ophthalmia neonatorum — conjunctivitis in the first 28 days of life. A notifiable disease.
• Causes:
  • Gonococcal — days 1–5; hyperacute, copious pus; risk of corneal perforation. IV or IM ceftriaxone.
  • Chlamydial — days 5–14; can cause pneumonia. Oral azithromycin or erythromycin.
  • Other bacteria; herpes simplex.
• Management: Same-day ophthalmology or paediatric review; swabs (including for chlamydia and gonorrhoea PCR); treat the mother and partner (sexual health).
• Sticky eye from a blocked tear duct — common and harmless; lid cleaning, no antibiotics unless infected.

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Corneal Abrasion and Foreign Body

• Corneal abrasion:
  • Cause — fingernail, paper, branch, contact lens.
  • Features — pain, watering, foreign body sensation, photophobia; stains with fluorescein.
  • Management:
    • Topical anaesthetic for examination only.
    • Chloramphenicol ointment four times daily for a few days.
    • Oral analgesia; cyclopentolate for comfort if large.
    • No patching needed.
    • Heals in 24–72 hours; review if not improving.
    • Contact lens wearer — cover Pseudomonas; refer.
  • Vertical linear scratches suggest a foreign body under the upper lid — evert the lid.
• Corneal foreign body:
  • Remove superficial bodies with a cotton bud or needle under topical anaesthetic (if trained); a rust ring may need specialist removal.
  • Antibiotic ointment afterwards.
• High-velocity injury (hammering metal on metal, grinding, drilling) — suspect an intraocular foreign body even if the eye looks normal: X-ray or CT of the orbits (not MRI — metal).
• Arc eye (welding, sunbeds, snow) — UV keratitis: severe pain and watering 6–12 hours after exposure, both eyes. Lubricants, antibiotic ointment, analgesia; settles in 24–48 hours.

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Chemical Injury

• An ophthalmic emergency — alkalis (cement, lime, oven cleaner, ammonia, drain cleaner) are worse than acids, because they penetrate deeper.
• Immediate action — irrigate before anything else:
  • Topical anaesthetic drops, then irrigate with at least 1–2 litres of saline or Hartmann's (or tap water if nothing else) for at least 20–30 minutes.
  • Hold the lids open; use a Morgan lens if available.
  • Check pH with litmus paper 5 minutes after stopping; continue until the pH is 7.0–7.5.
  • Sweep the fornices and evert the lids to remove particles (cement).
• Then: Acuity; fluorescein; urgent ophthalmology review.
• Bad signs: A white, blanched eye (loss of blood supply to the limbus — worse than a red eye), corneal haze.
• Treatment (specialist) — antibiotics, steroids, vitamin C, doxycycline, lubricants, cycloplegics; amniotic membrane grafts.

⚠️ Safety Pearl: For a chemical splash, irrigate first and ask questions later. Every minute of delay increases damage — don't wait to check acuity or call for help.

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Blunt Trauma and Blowout Fracture

• Hyphaema — blood in the anterior chamber (a fluid level):
  • Same-day ophthalmology.
  • Rest with head up; steroid and dilating drops; check pressure.
  • Risk of rebleeding and raised pressure; extra care in sickle cell disease.
  • Avoid NSAIDs and anticoagulants if possible.
• Orbital blowout fracture — a blow from a fist or ball breaks the thin orbital floor:
  • Double vision on looking up (inferior rectus trapped).
  • Numb cheek and upper lip (infraorbital nerve).
  • Sunken eye (enophthalmos); surgical emphysema — advise no nose blowing.
  • CT orbits; maxillofacial and ophthalmology review.
  • Children — "white-eyed blowout": trapped muscle with little bruising, nausea and vomiting, slow heart rate (oculocardiac reflex) — urgent surgery.
• Retrobulbar haemorrhage — orbital compartment syndrome:
  • After trauma or eye surgery, or on anticoagulants.
  • Painful, tense proptosis, falling vision, RAPD, restricted movements, hard eye.
  • Emergency lateral canthotomy and cantholysis within about 90–120 minutes to save the sight.
• Other — commotio retinae (retinal bruising), retinal detachment, lens dislocation, traumatic optic neuropathy.

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Penetrating Injury

• Clues:
  • Mechanism — sharp object, glass, high-velocity metal.
  • Reduced vision; teardrop or irregular pupil (pointing to the wound).
  • Shallow anterior chamber; prolapsed dark tissue (iris).
  • Seidel test — fluorescein streams away from a leaking wound.
  • Severe subconjunctival haemorrhage hiding a scleral rupture.
• Management:
  • Don't press on the eye; don't remove an impaled object.
  • Rigid eye shield (not a pad).
  • Keep nil by mouth (surgery); antiemetic (vomiting raises eye pressure); analgesia.
  • Tetanus status; IV or oral antibiotics (e.g. a fluoroquinolone) to prevent endophthalmitis.
  • CT orbits to look for a foreign body.
  • Immediate ophthalmology for surgical repair.
• Sympathetic ophthalmia — rare inflammation in the uninjured eye weeks to years after a penetrating injury.

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Drug Reference Table

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Spot the Emergency

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Exam-style Scenarios

1. A 68-year-old woman has a severe headache, vomiting and a red left eye that started in a dark cinema. The left pupil is fixed and mid-dilated, the cornea is hazy and the eye feels hard.
Answer: Acute angle-closure glaucoma.

• Immediate ophthalmology; lie flat.
• Acetazolamide 500 mg IV; timolol and apraclonidine drops; pilocarpine; analgesia and antiemetic.
• Laser iridotomy to both eyes once settled.

2. A 24-year-old contact lens wearer has a painful, photophobic right eye. Vision is 6/18 and there is a white spot on the cornea that stains with fluorescein.
Answer: Bacterial keratitis.

• Same-day eye casualty; remove lenses; send lenses and case for culture.
• Corneal scrape; intensive fluoroquinolone drops.
• Advice on lens hygiene; no sleeping or swimming in lenses.

3. A builder gets wet cement in his eye. He arrives at ED in pain.
Answer: Alkali chemical injury.

• Immediate topical anaesthetic and irrigation with at least 1–2 L of saline.
• Check pH after 5 minutes; continue until 7.0–7.5; remove particles from the fornices.
• Then acuity and fluorescein; urgent ophthalmology.

4. A 32-year-old man with ankylosing spondylitis has a painful, light-sensitive red eye with blurred vision and a small, irregular pupil.
Answer: Acute anterior uveitis (HLA-B27).

• Same-day ophthalmology.
• Steroid drops and cyclopentolate; monitor pressure.
• Advise early review for future attacks.

5. A 6-year-old has a swollen, red left upper lid after a cold. She has a fever, the eye is pushed forward and eye movements are painful.
Answer: Orbital cellulitis from ethmoid sinusitis.

• Admit; IV antibiotics; CT orbits and sinuses.
• Ophthalmology and ENT review; monitor vision and pupils.
• Surgical drainage if an abscess is present.

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Key Points

• Red eye red flags: reduced vision, real pain, photophobia, abnormal pupil, corneal opacity, contact lenses, trauma or chemicals.
• Conjunctivitis: normal vision; bacterial (sticky — often self-limiting), viral (watery, contagious), allergic (itchy).
• Subconjunctival haemorrhage: painless; check BP and INR.
• Episcleritis is benign; scleritis is painful, sight-threatening and linked to rheumatoid arthritis and vasculitis.
• Anterior uveitis: photophobia, ciliary flush, small pupil — steroid and dilating drops; think HLA-B27 and sarcoid.
• Acute angle closure: vomiting, haloes, fixed mid-dilated pupil, hard eye — acetazolamide, drops, laser to both eyes.
• Contact lens wearer with a painful red eye: refer the same day (Pseudomonas keratitis).
• Dendritic ulcer = HSV: topical antiviral, never steroid drops.
• Hutchinson's sign predicts eye involvement in zoster; oral antiviral within 72 hours.
• Orbital cellulitis: proptosis, painful restricted movements, reduced vision — IV antibiotics and CT.
• Chemical injury: irrigate immediately until pH is neutral; alkali is worse than acid.
• High-velocity injury: image for an intraocular foreign body (CT, not MRI).
• Retrobulbar haemorrhage needs urgent lateral canthotomy.

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Guidelines and Further Reading

• NICE Clinical Knowledge Summaries: Red eye; Conjunctivitis — infective and allergic; Corneal superficial injury; Herpes zoster
• College of Optometrists — Clinical Management Guidelines
• The Royal College of Ophthalmologists — guidance on ophthalmic emergencies and referral urgency
• RCEM — guidance on eye injuries in the emergency department
• BNF — for current doses

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