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Health condition · Clinically reviewed

Keratitis, a red painful eye that always needs the same-day view of an ophthalmologist.

Inflammation of the cornea is sight-threatening. The right scrape, the right drop and the right specialist decide whether the vision comes back.

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Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against the Royal College of Ophthalmologists, BSOM and peer-reviewed sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK guidance including fortified antibiotics, PHMB for Acanthamoeba and cenegermin for neurotrophic disease.

Key facts

Keratitis at a glance.

The essentials in plain English. What it is, the causes worth knowing and how it is treated in the UK today.

  • What it is

    Inflammation of the cornea, the clear window at the front of the eye. Sight-threatening and often an ophthalmic emergency.

  • Two broad groups

    Infective (bacterial, viral, fungal, Acanthamoeba) and non-infective (UV, neurotrophic, exposure, dry, autoimmune, drug-induced).

  • Contact lens link

    Contact lens wear, especially overnight or with tap-water exposure, is the biggest single risk factor for microbial keratitis in the UK.

  • Classic triad

    Eye pain, photophobia and reduced vision, usually with a red eye. Always a same-day ophthalmology problem.

  • Diagnosis

    Slit-lamp examination with fluorescein, corneal scrape for microscopy and culture, PCR for viruses, confocal microscopy for Acanthamoeba.

  • Treatment

    Targeted to the cause: fortified antibiotics, antivirals, antifungals, PHMB, cenegermin or, in perforation, corneal glue and transplant.

Why this guide matters

Speed and specificity save sight.

Keratitis is common enough to matter and rare enough to be missed. The three points below shape everything else on this page.

  • It is a same-day emergency

    A painful, red, photophobic eye with blurred vision needs eye casualty today. Do not wait, do not self-medicate and do not put a lens back in.

  • The cause changes the drug

    Bacterial, viral, fungal and Acanthamoeba disease each need different treatment. Corneal scrape and specialist microbiology matter.

  • Modern options exist

    Fortified antibiotics, PHMB, cenegermin and, when needed, corneal transplant have transformed outcomes over the last decade.

How the diagnosis is made

From first symptom to a targeted plan.

The steps a UK eye casualty or specialist corneal service will normally follow, in order.

  1. 01

    Assessing

    Focused history

    Contact lens habits, water exposure, trauma, cold sores, shingles, ocular medications and any autoimmune disease all shape the differential.

  2. 02

    Assessing

    Same-day ophthalmology review

    A painful, red, photophobic eye with reduced vision is treated as an emergency by A&E or an eye-casualty service.

  3. 03

    Assessing

    Visual acuity and red flags

    Snellen acuity, pupil check and lid function help gauge severity and pick up exposure or neurotrophic causes.

  4. 04

    Confirming

    Slit-lamp with fluorescein

    The definitive first look, done by a specialist ophthalmologist to map the epithelial defect, stromal infiltrate and any hypopyon.

  5. 05

    Confirming

    Corneal scrape

    Sent for Gram stain, microscopy, culture and, when needed, PCR. Specialist-commissioned microbiology guides fortified drop selection.

  6. 06

    Confirming

    Confocal microscopy

    Reserved for suspected Acanthamoeba or fungal disease. Only available in specialist-commissioned corneal centres such as Moorfields.

  7. 07

    Planning

    MDT and follow-up plan

    Complex or resistant cases are managed by a specialist-commissioned corneal MDT with a clear escalation and review pathway.

Typical timeline: from first symptom to a targeted plan within hours, not days.

Symptoms

What keratitis actually feels like.

The classic pattern of pain, redness, light sensitivity and reduced vision. And the features that mean it is time to escalate.

  • Eye pain

    A deep, boring ache that is often worse than the eye looks. Never dismiss severe pain in a contact lens wearer.

  • Redness

    Circumcorneal injection is typical, sometimes with a visible white or grey spot on the cornea itself.

  • Photophobia

    Bright light is unbearable and the eye squeezes shut. A sensitive marker of any corneal inflammation.

  • Reduced vision

    Blurring that does not clear with a blink suggests a central infiltrate or oedema and is always urgent.

  • Tearing and discharge

    Watery in viral disease, mucopurulent in bacterial disease. Discharge patterns nudge the diagnosis.

  • Foreign body sensation

    A gritty feeling as if something is in the eye. Common in exposure, UV and early infective keratitis.

  • Dendritic ulcer

    A branching fluorescein-staining ulcer is the signature of herpes simplex keratitis and needs antivirals, not steroids.

  • Red flag - contact lens plus pain

    Any lens wearer with a painful red eye is a microbial keratitis until proven otherwise. Same-day eye casualty, lens out.

Treatment

How keratitis is treated in the UK.

Fortified antibiotics first for bacterial disease, targeted antivirals or antifungals when needed, and specialist-commissioned drops or surgery for the harder cases.

  • Fortified antibiotic drops

    Vancomycin with gentamicin or ceftazidime, or monotherapy with ofloxacin or ciprofloxacin. Hourly day and night in early bacterial disease.

  • Topical and oral aciclovir

    For herpes simplex keratitis, alongside ganciclovir gel (Zirgan). Steroids are avoided until the epithelium has healed.

  • Antifungals - natamycin and more

    Natamycin, voriconazole or amphotericin for Fusarium, Candida and Aspergillus. Specialist-commissioned and often prolonged.

  • PHMB and chlorhexidine

    The mainstay for Acanthamoeba keratitis. Months of intensive treatment in a specialist-commissioned corneal service.

  • Selective topical steroids

    Reserved for after infection is controlled, to calm scarring. Always specialist-led and never a first move.

  • Cenegermin (Oxervate)

    Recombinant nerve growth factor eye drops for moderate-to-severe neurotrophic keratitis. Approved and specialist-commissioned via our neurotrophic keratitis clinic.

  • Corneal glue and amniotic membrane

    For threatened or small perforations. A holding measure while planning definitive surgery in a corneal centre.

  • Corneal transplant (keratoplasty)

    For deep scarring or perforation not controlled by drops. Specialist-commissioned and life-changing when needed.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

Your ophthalmologist knows your eyes and history and can tell you which parts apply to you. If in doubt, get seen the same day.

  • Royal College of Ophthalmologists (RCOphth). Guidance on microbial and non-microbial keratitis.

  • British Society for Ophthalmic Microbiology (BSOM). Corneal scrape and fortified antibiotic protocols.

  • NICE. Herpes simplex ocular disease and dry-eye guidance.

  • MHRA and NHS England. Cenegermin (Oxervate) commissioning for neurotrophic keratitis.

Red flags

When keratitis needs urgent attention.

Nearly every suspected keratitis is a same-day problem. These features raise the ceiling from urgent to emergency.

  • Contact lens wearer with a red, painful eye

    Assume microbial keratitis. Remove the lens, keep it and its case for microbiology, and attend eye casualty the same day.

  • Sudden drop in vision

    Central infiltrate, hypopyon or corneal oedema all threaten sight. Never wait for a routine appointment.

  • Corneal thinning or perforation

    A rapidly thinning cornea or aqueous leak needs emergency corneal-service review and often corneal glue.

  • Post-shingles neurotrophic ulcer

    A painless, non-healing epithelial defect after herpes zoster ophthalmicus can progress silently. Refer early.

  • Facial nerve palsy with exposure

    Incomplete lid closure risks exposure keratitis. Related content: see our guides to facial nerve disorders and dry eye.

  • Tap water and contact lenses

    Showering, swimming or rinsing lens cases with tap water sharply raises Acanthamoeba risk. Report exposures early.

  • Immunosuppression

    Steroids, chemotherapy or transplant medication mask signs and raise the stakes. Have a low threshold for scraping.

  • Autoimmune corneal melt

    Rheumatoid arthritis, GPA or Mooren ulcer can dissolve the cornea. Specialist-commissioned rheumatology and corneal input is essential.

  • Welding or snow exposure

    Severe UV keratitis follows arc-eye or snow blindness by 6 to 12 hours. Painful but usually self-limiting with lubrication and analgesia.

Living with it

A treatable emergency, with a clear pathway.

Four things that make the biggest difference through and after an episode. Lens hygiene, drop adherence, keeping follow-up and protecting the healing cornea.

A quiet reminder

A missed drop today is another day of healing tomorrow.

Corneal infections respond to consistency. Small, steady effort protects vision better than a burst of intensity that fades.

  1. 01 Lens hygiene

    Respect your lenses

    Never sleep, shower or swim in daily lenses. Replace cases monthly and never top up solution. Most severe keratitis in the UK is preventable.

  2. 02 Adherence

    Take the drops as prescribed

    Hourly regimes are exhausting but essential. Set alarms, keep a chart and do not stop early even when the eye feels better.

  3. 03 Follow-up

    Keep every review

    Corneal infections change day to day. Follow-up in a specialist eye service is how sight is protected.

  4. 04 Recovery

    Protect the healing cornea

    Sunglasses, lubricants and, sometimes, a soft bandage lens help. Return promptly if pain, redness or blur come back.

Frequently asked

Everything we get asked about keratitis.

Quick answers on contact lenses, dendritic ulcers, Acanthamoeba, neurotrophic disease and when a transplant is needed.

  • What is keratitis?

    Keratitis is inflammation of the cornea, the clear window at the front of the eye. It can be infective (bacterial, viral, fungal or Acanthamoeba) or non-infective (UV, neurotrophic, exposure, dry, autoimmune or drug-induced). It is sight-threatening and needs same-day ophthalmology assessment.

  • Is keratitis an emergency?

    Yes. A painful, red, photophobic eye with reduced vision, particularly in a contact lens wearer, is treated as microbial keratitis until proven otherwise. Attend eye casualty or A&E the same day, take your lenses and case with you and do not put drops in before you are seen.

  • What causes contact lens keratitis?

    The commonest bacteria are Pseudomonas, Staphylococcus and Streptococcus. Overnight wear, tap water exposure, poor case hygiene and topping up solution all raise the risk. Acanthamoeba, a water-borne parasite, is rarer but severe and specialist-commissioned to treat.

  • What is a dendritic ulcer?

    A branching, tree-like ulcer on the cornea that stains with fluorescein. It is the classic sign of herpes simplex keratitis and is treated with topical and oral aciclovir plus ganciclovir gel. Topical steroids are avoided until the epithelium has healed.

  • What is neurotrophic keratitis?

    A form of corneal disease where the nerve supply is damaged, often after shingles, surgery or diabetes, and the cornea cannot heal itself. Cenegermin (Oxervate), a recombinant nerve growth factor eye drop, is approved and specialist-commissioned. Severe cases can need a corneal transplant.

  • Will I need a corneal transplant?

    Most people recover with drops alone. A corneal transplant (keratoplasty) is reserved for deep scarring, perforation or infection that will not settle. It is specialist-commissioned surgery done in a corneal centre and can restore useful vision even after severe keratitis.

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