Microscopy Findings

• PAS-stained preparation (pink/magenta images): Thin, uniform, septate hyphae with acute-angle (~45°) branching running in parallel bundles - morphology consistent with Aspergillus or Fusarium species
• Wet mount (unstained image): Thin septate hyphae with occasional branching visible on direct microscopy

Treatment of Septate (Filamentous) Fungal Keratitis

1. First-Line Topical Antifungals

Natamycin 5% is the only FDA-approved topical antifungal for mycotic keratitis. All others require compounding.

2. Epithelial Debridement

• Remove the epithelium over the lesion to enhance antifungal penetration - topical antifungals penetrate poorly through intact epithelium
• Regularly debride mucus and necrotic tissue with a spatula

3. Cycloplegia

• Cyclopentolate 1% TID, or
• Atropine 1% BID-TID if hypopyon, fibrin, or significant anterior chamber reaction is present

4. Strict Steroid Avoidance

• Stop all topical steroids immediately. If already on steroids, taper and discontinue rapidly. Steroids are a major predisposing factor and will worsen fungal keratitis.

5. Systemic Antifungals (for severe, deep, or limbus-threatening disease)

• Voriconazole: 400 mg PO BID x 1 day (loading), then 200 mg PO BID
• Itraconazole: 200 mg PO OD, reduce to 100 mg OD
• Fluconazole: 200 mg PO BID
• Posaconazole: 300 mg PO BID x 1 day, then 300 mg OD

6. Intrastromal / Intracameral Injections (refractory cases)

• Voriconazole 50 mcg/0.1 mL intrastromal depot
• Amphotericin B 10 mcg/0.1 mL intrastromal or intracameral
• Useful when surface therapy is failing and culture sensitivities are known

7. Anticollagenase therapy

• Doxycycline 100 mg BID - for its anticollagenase effect when significant corneal thinning is present

8. IOP Monitoring

• Measure IOP regularly (Tono-Pen preferred). Treat elevated IOP if present.

9. Broad-spectrum Antibiotic Cover

• Consider topical broad-spectrum antibiotics to prevent or treat bacterial co-infection

10. Surgical Options (medical treatment failure)

• Superficial keratectomy - debulk the lesion
• Therapeutic penetrating keratoplasty (TPK) - when medical therapy fails, ideally before infection reaches the limbus; include intracameral antifungal at time of surgery
• Deep anterior lamellar keratoplasty (DALK) - consider; note anterior lamellar has higher recurrence risk
• Anterior chamber washout + intracameral antifungal - for cases with stable corneal infiltrate but enlarging endothelial exudation

Follow-Up

• Daily review initially
• Response is much slower than bacterial keratitis - weeks to months of treatment expected
• Stability (not necessarily improvement) after starting treatment is a favorable sign
• Epithelial healing alone does NOT confirm treatment success - fungus can still be active in deep stroma
• Hospital admission may be needed for compliance

Can Moxifloxacin Ointment Be Used in Septate Fungal Keratitis?

Short answer: Not as primary/sole treatment. Drops may serve a limited adjunctive role; ointment has no established role.

Why Moxifloxacin Is NOT an Antifungal

• They reduce drug bioavailability at the stromal level compared to drops
• They can trap organisms under a film at the corneal surface
• The base (petrolatum/mineral oil) does not aid antifungal penetration

What the Evidence Actually Shows (About Drops, Not Ointment)

Key points from evidence:

• Any activity is only demonstrated for moxifloxacin drops (0.3-0.5%), not ointment
• Activity against Fusarium is modest at best; none against Aspergillus
• The mechanism is likely inhibition of fungal topoisomerase II at very high concentrations - but achievable corneal levels are insufficient compared to dedicated antifungals
• It may explain why some fungal ulcers appear to "improve" when initially treated empirically as bacterial before the diagnosis is confirmed

What to Do in Your Case

1. Do NOT use moxifloxacin ointment as antifungal treatment - it will not work
2. Start Natamycin 5% drops Q1-2h immediately (first-line for filamentous/septate fungi)
3. Add Voriconazole 1% drops (compounded) if response is poor
4. Moxifloxacin drops may be kept as a co-prescription solely to prevent bacterial superinfection - but this is the only justifiable role
5. Stop steroids if on any