5.13 Keratitis, Microbial, Fungal

eyes.nhs.scot/
Eyecare Guidelines/
Section 5 - Cornea/
5.13 Keratitis, Microbial, Fungal

Date of last review:

10/04/2026

Date of next review:

10/04/2028

Date of publication:

20/04/2026

Differential diagnosis ⁽¹⁾

Bacterial Keratitis
Corneal inflammatory non-infectious lesions (contact lens related or marginal keratitis)
Peripheral, small (0.5-1.5 mm) with less anterior chamber response
Macro corneal erosion in vernal keratoconjunctivitis
Acanthamoeba keratitis (AK)
Suspect AK if multiple epithelial or subepithelial infiltrates, perineural infiltrates or dendritiform epithelial lesions
Herpes Simplex keratitis

Possible management by optometrist

Advice

Immediately stop contact lens wear ⁽¹⁾
Advise patients to retain lenses and cases for possible microbiological culture ⁽¹⁾
Maintain a low threshold for AK suspicion if recent contact with water (e.g. swimming) ⁽⁷⁾

Treatment ⁽¹⁾

None – same day emergency referral

Typical adult dosage/duration

(Blue text = IP, black text = non-IP)

Not applicable for this condition

Regimens should be adjusted according to severity and patient factors (e.g. age, weight, pregnancy, renal function). Prescribing should follow local formulary and national guidance where available ⁽⁷⁾.

In cases of known sensitivities, please consult local formularies for alternative options ⁽⁷⁾.

Further management options ⁽¹⁾

Emergency referral (same day)

Possible management in secondary care or local/community pathways where available ⁽¹⁾

See further management options
Corneal scraping for culture and antibiotic sensitivity, due to evolving pathogen profiles and resistance
Polymerase chain reaction (PCR) testing where available
Possible hospital admission for poor compliance, overnight therapy, or severe lesions (axial, ≥6 mm, or ≥50% stromal thinning)
Cycloplegics for comfort
IOP lowering therapy if required
Topical steroids only once infection is controlled (evidence remains limited)
Corneal crosslinking may be considered in selected cases
Amphotericin B 0.15% for yeast infections (e.g. Candida)
Usually requires combined topical (natamycin 5%, econazole 1%, or voriconazole 1%) and oral therapy (e.g. oral voriconazole)

College of Optometrists Clinical Management Guideline⁽¹⁾

Microbial keratitis (bacterial, fungal) - College of Optometrists

*With special thanks to The College of Optometrists for providing the evidence framework for diagnosis and management from the Clinical Management Guidelines (CMGs) for this condition. All references to the College/CMGs are included where appropriate and form the basis of the Community Eyecare Guidelines.

Guidance is informed by the following sources

College of Optometrists Clinical Management Guidelines Clinical Management Guidelines - College of Optometrists
Advisory alignment with the College of Optometrists Formulary Optometrists' Formulary - College of Optometrists
Advisory alignment with the BNF BNF (British National Formulary) | NICE
Advisory alignment with the Summary Product Characteristics taken from the EMC Home - electronic medicines compendium (emc)
Advisory alignment with Scottish Health Board formularies (where a clear majority is present) *
Advisory alignment with expert consensus (CEGG), informed by sources 2-5 above
Advisory alignment with expert consensus (CEGG)
“Annex C of the Statement” https://www.eyes.nhs.scot/for-professionals/legislation/

* Scottish formularies should be available within the Prescribing section of your Health Board pages on the eyes.nhs.scot website. If unavailable, contact your local Health Board for further information; Health Boards landing page

If you have a query relating to this page, please email NSS.ComEyecareGuidelineGroup@nhs.scot

Disclaimers

CEG disclaimer for guidelines awaiting update:

The Eyecare Guidelines area of the eyes.nhs.scot website (“Website”) is intended as a reference source for education and clinical decision support and is intended for use by ophthalmic healthcare professionals working in Scotland.

As such, the Eyecare Guidelines are not intended for use by the general public and do not replace the advice of a healthcare professional. Members of the public should seek advice directly from their optometrist.

Before reading the Eyecare Guidelines or making any management decisions based upon them, all users should read the ‘supporting information’ page which gives more detail around the content of the Guidelines and useful website links [link to Supporting Information page].

Users should note that that the Eyecare Guidelines guidance is not mandatory. The guidelines will not be suitable for every situation, and they are not intended to be a substitute for specialist expertise and clinical judgement. Users assume all responsibility for using/interpreting the information within the Eyecare Guidelines section of the website. Users should also note that the Eyecare Guidelines should not be adhered to in isolation and should be considered in conjunction with other national and locally available guidance/pathways.

Users should note that Guidelines which have not yet been updated should be considered with caution. Where the Eyecare Guidelines contain links to other sites and/or resources provided by third parties, these links are provided for information only.

Accordingly, to the maximum extent permitted by law, the Eyecare Guidelines are made available on the basis of excluding all representations, warranties, conditions and other terms (including, without limitation, the conditions implied by law of satisfactory quality, fitness for purpose and the use of reasonable care and skill) which, but for this disclaimer, might have effect in relation to the Eyecare Guidelines.

CEG disclaimer for updated guidelines:

Users should note that that the Eyecare Guidelines guidance is not mandatory. The guidelines will not be suitable for every situation and they are not intended to be a substitute for specialist expertise and clinical judgement. Users assume all responsibility for using/interpreting the information within the Eyecare Guidelines section of the website. Users should also note that the Eyecare Guidelines should not be adhered to in isolation and should be considered in conjunction with other national and locally available guidance/pathways. 

Updating the Eyecare Guidelines requires a continuous process; the date of the last review for each guideline will be clearly noted on each guideline. Users must consider these dates before using the guidance.

While the Common Services Agency (“NSS”) makes reasonable efforts to ensure that the information on the Eyecare Guidelines area of the Website is correct, the Website is provided ‘as is’ and NSS does not warrant the accuracy and completeness of the material on the Website. NSS may make changes to the Website at any time without notice. Some of the material on the Website may be out of date, and NSS makes no commitment to update such material. Users should note that some Eyecare Guidelines on the Website have not been updated for several years and should be considered with caution.

Where the Eyecare Guidelines section of the Website contains links to other sites and or resources provided by third parties, these links are provided for information only. NSS has no control over, and no liability in respect of, the content of these sites and resources.

Accordingly, to the maximum extent permitted by law, the Eyecare Guidelines area of the Website is made available by NSS on the basis that NSS excludes all representations, warranties, conditions and other terms (including, without limitation, the conditions implied by law of satisfactory quality, fitness for purpose and the use of reasonable care and skill) which, but for this disclaimer, might have effect in relation to the Website. 