This material is intended for ophthalmologists and other qualified healthcare professionals. The Russian section is based on the Ministry of Health clinical guideline “Keratitis” 2025 (ID 1010_1). The international section is supplementary and does not replace national guidance, official prescribing information or local SOPs.
Identify potentially vision-threatening disease
The 1–2–3 ACT criteria are used here as an additional risk-stratification tool. Meeting any criterion should increase concern for vision-threatening microbial keratitis and supports microbiological sampling and consideration of more intensive initial treatment.
Anterior chamber cell ≥1+ by SUN grading: 6–15 cells in a 1 × 1 mm slit beam field.
Additional high-risk features include multiple or satellite infiltrates, deep stromal involvement and progressive stromal melt.
The nearest edge of the stromal infiltrate lies no more than 3 mm from the anatomical centre of the cornea.
treat the case as potentially vision-threatening → obtain corneal scraping for microscopy and culture before the first antibiotic dose when this does not cause a clinically meaningful treatment delay → consider a more intensive initial regimen, including locally prepared fortified antibiotics where appropriate, with daily review until stabilisation in severe disease.
Progressive thinning, descemetocele or perforation; rapidly increasing infiltrate area or depth; extension to sclera or intraocular structures; infiltrate involving a surgical wound, corneal suture or lamellar interface; suspected gonococcal infection; or inability to deliver the required treatment frequency and follow-up.
Document the baseline before treatment
Recording the same parameters at each review makes change in the epithelial defect, stromal infiltrate and inflammatory response objectively comparable.
- Contact-lens wear, overnight wear, exposure of lenses to tap water, swimming pools or hot tubs
- Trauma, particularly with vegetative material
- Recent surgery, corneal sutures or keratoplasty
- Previous topical antibiotics or corticosteroids
- Ocular-surface disease, immunocompromise or diabetes mellitus
- Uncorrected and best-corrected visual acuity in each eye
- Pain severity, photophobia and character of ocular discharge
- Intraocular pressure only when there is no major thinning or risk of perforation
- Status of the fellow eye
- Location, size and depth of the infiltrate
- Size of the epithelial defect
- Margins, satellite lesions, stromal melt and degree of thinning
- Anterior chamber cell, fibrin, hypopyon height and endothelial plaque
- Anterior-segment photography using a comparable scale
For a small peripheral infiltrate, document its distance from the corneal centre, stromal depth, epithelial-defect size and subsequent change.
Clinical archive of M. Y. Shemyakin
Paracentral location and lesion size increase the need for microbiological diagnosis, adequate initial treatment intensity and early reassessment.
Clinical archive of M. Y. Shemyakin
Stromal infiltrate: ___ × ___ mm; location: ___; distance from nearest infiltrate edge to corneal centre: ___ mm; stromal depth: ___; epithelial defect: ___ × ___ mm; corneal thinning: ___%; anterior chamber cell by SUN grade: ___; hypopyon: ___ mm; scaled photography: performed / not performed.
When to obtain corneal specimens
A small peripheral infiltrate without stromal melt or marked anterior chamber inflammation may sometimes be treated empirically. Central, large, deep, postoperative or atypical disease warrants microbiological sampling before antimicrobial treatment when this does not delay therapy.
- Central infiltrate; lesion >2 mm; two or more adjacent lesions; marked deep stromal involvement or stromal melt.
- Anterior chamber cell ≥1+ by SUN grading, hypopyon or other features of vision-threatening disease.
- Previous corneal surgery; infiltrate involving a suture, surgical wound or lamellar interface.
- Chronic or recurrent course, multiple infiltrates, atypical morphology or failure to respond as expected to broad-spectrum antibacterial therapy.
- Suspicion of fungal, Acanthamoeba, Nocardia or nontuberculous mycobacterial infection.
Corneal scraping is obtained with a sterile instrument after topical anaesthesia. Superficial conjunctival discharge alone is less informative. An infected or loose corneal suture should be removed and sent for microbiological examination when clinically indicated.
In contact-lens wearers, culture or analysis of the lens, storage case and solution may provide additional information. A hypopyon in isolated keratitis is often sterile; anterior-chamber or vitreous sampling is not routine and is reserved for concern about intraocular extension.
| Clinical situation | Culture | Minimum diagnostic set | When to expand |
|---|---|---|---|
| Small peripheral infiltrateNo stromal melt or substantial anterior chamber inflammation | Optional | Clinical assessment and close follow-up | If worsening occurs, obtain microbiology before changing therapy when feasible |
| Central / large / deep lesionVision-threatening features | Yes | Direct microscopy including Gram stain; culture on blood and chocolate agar and in liquid media | Add Sabouraud and other media according to history and suspected etiology |
| Atypical or postoperative disease | Yes | Bacterial culture plus targeted stains | KOH and/or calcofluor white, acid-fast stains, special media for Acanthamoeba and nontuberculous mycobacteria as indicated |
Use morphology to refine — not replace — etiologic testing
Clinical appearance can help broaden or narrow the differential diagnosis but cannot reliably identify the organism by itself. Images are presented as attributed clinical examples.
The photographs illustrate clinical morphology and do not replace microbiological or, when indicated, molecular confirmation.
Bacterial keratitis
Acute onset, a suppurative stromal infiltrate, an epithelial defect and anterior chamber inflammation are typical. Morphology alone does not identify the causative organism.
- Contact-lens wear, corneal trauma, surgery or corneal sutures
- Purulent discharge and rapidly progressive stromal disease
- Hypopyon, deep infiltration and stromal melt
- Assess for vision-threatening features
- Perform corneal scraping in severe or atypical disease
- Start antibacterial therapy immediately after sampling when sampling is indicated
Visual assessment should trigger appropriate expansion of the differential diagnosis and investigations; it should not create false confidence about the causative organism.
Russian clinical guidance, international guidance and practical differences
The sources are deliberately separated so that national Russian recommendations are not conflated with supplementary international approaches.
Russian Ministry of Health clinical guideline “Keratitis” 2025, official prescribing information for the specific medicinal product and local SOPs. International regimens are shown separately.
Clinical guideline “Keratitis”
ID 1010_1 · adults and children · scheduled review no later than 2027
- Ofloxacin: 1–2 drops every 4–6 hours.
- Ciprofloxacin: 1–2 drops every 4 hours.
- Levofloxacin: 1–2 drops every 2 hours, not exceeding 8 instillations per day.
- Netilmicin: 1–2 drops 3 times daily; tobramycin: 1–2 drops every 4 hours.
- Treatment duration is determined by the approved prescribing information and clinical response; the guideline gives an indicative course of 5–10 days.
- The guideline also includes topical antiseptic treatment in accordance with the relevant prescribing information.
- When keratitis is complicated by iridocyclitis and there is a risk of posterior synechiae, mydriatic/cycloplegic treatment may be considered in accordance with the guideline and approved product information.
- Systemic antibacterial treatment may be prescribed when clinically indicated, including extensive or complicated bacterial disease.
Risk-adapted treatment intensity
Supplementary international guidance; it does not replace national Russian recommendations
- A topical fluoroquinolone at approximately 2–6-hour intervals may be used for a small peripheral infiltrate without vision-threatening features, according to clinical severity and local practice.
- More intensive fluoroquinolone treatment, often approximately hourly initially, with early clinical reassessment; the exact regimen depends on severity and the local protocol.
- After scraping and culture, locally prepared fortified treatment may be considered: tobramycin or gentamicin 15 mg/mL combined with vancomycin 25–50 mg/mL, using an intensive instillation schedule. This approach requires an appropriate local SOP and individual prescribing decision.
- Once organism identification and susceptibility data are available, treatment should be targeted and the antibacterial spectrum narrowed when clinically appropriate to reduce toxicity.
- Topical corticosteroids may be considered only after 24–48 hours of effective antibacterial treatment when bacterial etiology has been established or there is clear clinical improvement.
- Topical corticosteroids should not be started when fungal, Acanthamoeba or Nocardia keratitis remains a significant possibility.
- Severe disease requires daily examination until stabilisation.
Key practical differences
| Clinical question | Russian Ministry of Health guideline 2025 | AAO PPP 2024 / 1–2–3 ACT |
|---|---|---|
| Role of the document | Primary national reference together with approved prescribing information and local SOPs. | Supplementary international framework. |
| Initial treatment intensity | Provides medicinal products and dosing schedules in line with approved prescribing information. | Frequency and choice of monotherapy versus combination treatment are more explicitly linked to the risk of visual loss. |
| Fortified antibiotics | Not presented as a detailed standard first-line regimen. | Considered for large, central, deep and other vision-threatening ulcers. |
| Topical corticosteroids | Use during active infection requires confirmation of bacterial etiology and assessment of the response to antibacterial treatment. | May be considered after 24–48 hours of effective antibacterial treatment once fungal, Acanthamoeba and Nocardia infection have been excluded. |
| Monitoring | Management is guided by etiology and the risk of complications. | Severe disease warrants daily review until stable; lack of improvement over 24–48 hours should trigger diagnostic and therapeutic reassessment. |
Judge treatment by reproducible clinical change
In severe disease, examine the patient daily until stabilisation. Failure to improve or progression during the first 24–48 hours requires reassessment of the diagnosis, treatment delivery, organism and need for surgical intervention.
Inflammatory signs can transiently appear worse during the first 24–48 hours even when the organism is susceptible. Treatment changes should therefore be based on the overall pattern, particularly infiltrate area and depth, epithelial-defect size and stromal destruction.
Check the actual instillation frequency, microscopy and culture results, antimicrobial susceptibility, medication-related epithelial toxicity, atypical or mixed infection, biofilm, infected sutures or foreign material, and whether surgical treatment is indicated.
Even after active infection has resolved, visual outcome is determined by the location and density of residual scarring.
Clinical archive of M. Y. Shemyakin
This pattern requires differentiation between persistent infection and non-infectious stromal thinning, together with timely assessment of perforation risk.
Clinical archive of M. Y. Shemyakin
Reassess the cause of treatment failure systematically
This is a structured reassessment framework, not an automated prescribing system. It is intended to prevent escalation of the same treatment without reconsidering the diagnosis.
The presumed etiology may be wrong
Reassess the possibility of fungal, Acanthamoeba, herpetic, Nocardia or nontuberculous mycobacterial keratitis, particularly when the history or morphology is atypical.
- Reassess the history, risk factors and clinical morphology.
- Expand microscopy, culture and molecular testing when indicated.
- Until the etiology is clarified, avoid treatment that could worsen an alternative infection, especially premature topical corticosteroids.
A persistent epithelial defect and stromal damage may reflect impaired corneal innervation and epithelial repair rather than persistent infection.
Clinical archive of M. Y. Shemyakin
When response is poor, distinguish persistent infection from medication-related epithelial toxicity and neurotrophic disease by integrating changes in the infiltrate, epithelial defect, stromal destruction and microbiology.
Choose the most appropriate next step
Composite educational scenario. The photograph illustrates the morphology of a paracentral corneal ulcer and does not depict the described patient.
A 43-year-old contact-lens wearer presents with pain and reduced vision
There is a 2.5-mm central stromal infiltrate with a corresponding epithelial defect, anterior chamber cell 1+ by SUN grading and a 1-mm hypopyon. No antibacterial therapy has yet been used.
What is the most appropriate first step?Russian and international source documents
Primary sources open in a new tab. This synopsis should be medically re-reviewed when a core guideline or prescribing source is updated.