This patient-education article is written by the cornea service at Suraj Eye Institute, Nagpur.

What is Fungal Keratitis?

Fungal keratitis is an infection of the cornea by yeasts or filamentous fungi. Unlike bacterial keratitis, fungal disease is typically slow and indolent — pain and vision loss may develop over days to weeks rather than hours. This deceptive slow onset, together with the fact that the infiltrate often looks dry and feathery rather than wet and creamy, makes fungal keratitis easy to misdiagnose as bacterial unless it is specifically considered.

In Central India, fungal keratitis is particularly common in agricultural and outdoor workers who sustain vegetative corneal injuries (paddy husk, sugarcane leaf, branches, mud). The two main groups of organisms are filamentous moulds (Fusarium, Aspergillus) — commoner in this region — and yeasts (Candida) — commoner in eyes with chronic ocular surface disease.

Fungal Corneal Ulcer — Key Features

Fungal Corneal Ulcer — Key Slit-Lamp Features

Feathery margins Satellite lesions

Immune ring (faint, around main infiltrate)

Hypopyon (may be present)

Figure 1. Classical features of fungal keratitis. The infiltrate is dry-looking, raised and white-grey with characteristic feathery margins that radiate fine projections into the surrounding cornea. Small satellite infiltrates appear around the main lesion. A faint immune ring may encircle the infiltrate, and a hypopyon (layered pus in the anterior chamber) is common in advanced disease. The eye is less injected than in bacterial keratitis of similar severity.

Risk Factors

  • Corneal injury with vegetable matter — the single most important risk factor in Central India (paddy husk, sugarcane leaf, wood, branches, mud splash)
  • Topical steroid use on an undiagnosed corneal ulcer — steroids dramatically worsen fungal keratitis
  • Chronic ocular surface disease, especially with prior topical steroid use (Candida)
  • Outdoor occupation, agricultural work
  • Diabetes mellitus and other forms of immunosuppression

Symptoms

The classic story is days to weeks of slowly worsening pain, redness, watering and blurred vision after a minor injury (often a branch, a leaf, or a fall in a field). Patients often present after initial treatment with broad-spectrum antibiotics has failed.

How Fungal Keratitis is Diagnosed

Diagnosis is suggested by the slit-lamp appearance and confirmed by laboratory tests on a corneal scraping:

  • KOH (potassium hydroxide) wet-mount — rapid bedside test that demonstrates fungal hyphae or yeast forms within minutes
  • Gram stain
  • Culture on Sabouraud dextrose agar — identifies the species (may take 1–2 weeks)
  • PCR in selected cases
  • Confocal microscopy can visualise hyphae in vivo where available

Treatment

Fungal keratitis is treated with intensive antifungal therapy, usually for several weeks:

  • Topical natamycin 5 % — the first-line drug for filamentous fungal keratitis (Fusarium, Aspergillus); given hourly initially
  • Topical voriconazole 1 % — an alternative or adjunct, particularly effective against Aspergillus; better corneal penetration
  • Topical amphotericin B 0.15 % for Candida
  • Oral voriconazole / itraconazole as an adjunct in deep or large ulcers
  • Intrastromal or intracameral voriconazole injections for deep, non-responding disease
  • Therapeutic penetrating keratoplasty when medical treatment fails or perforation has occurred
Do not use steroid drops on an undiagnosed corneal ulcer. Topical steroids dramatically worsen fungal keratitis and can lead to rapid perforation. Steroids are only added late, by a cornea specialist, once the infection is clearly under control.
✔ Fungal Keratitis Care at Suraj Eye Institute

Fungal keratitis is common in Nagpur and the surrounding agricultural belt. Our on-site microbiology service receives corneal scrapings for KOH wet-mount, Gram stain and culture, and we have institutional protocols for early initiation of natamycin and voriconazole. For non-responding eyes we offer intrastromal or intracameral voriconazole injections and therapeutic corneal transplantation when medical treatment fails.

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Frequently Asked Questions

I only had a tiny scratch from a leaf — can it really turn into this?
Yes, and this is the classical pattern in Central India. A small injury from vegetable matter (a paddy stalk, sugarcane leaf, mud or branch) introduces fungal spores into the cornea. Symptoms develop slowly over days, by which time the infection is established. Any eye injury from organic material should be reviewed within 24 hours.

Why does fungal keratitis take so long to treat?
Antifungal drugs penetrate the cornea less easily than antibiotics, and fungal organisms grow more slowly than bacteria. Treatment typically continues for four to eight weeks, sometimes longer. Frequent slit-lamp review tells us when the ulcer is healing and when treatment can be reduced.

My eye doctor started me on antibiotic drops and it got worse — why?
Antibiotics do not treat fungi. If a corneal ulcer fails to improve on antibiotic drops within two to three days, fungal infection (or Acanthamoeba) must be considered and a corneal scraping repeated. The slow tempo of fungal disease often delays the right diagnosis.

Will I need a corneal transplant?
Most fungal ulcers heal with intensive medical treatment but leave a scar. Therapeutic transplantation is reserved for ulcers that perforate, do not respond to maximum medical treatment, or are advanced at presentation. Visual rehabilitation transplantation may follow months later if the scar reduces vision.

How can I avoid this happening again?
Protective eyewear when handling crops, branches, leaves, mud or any vegetable matter; immediate irrigation with clean water after any eye injury; and same-day medical review for any persistent pain or red eye after a minor injury are the key preventive steps.

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