Fungal Keratitis
A serious fungal infection of the cornea that can threaten vision
Quick Facts
- Type: Eye (corneal) infection
- Common triggers: Plant or soil injury, contact lenses
- Notable feature: Often slow to diagnose and treat
- Seek urgent care: Persistent painful red eye after an eye injury
Overview
Fungal keratitis is an infection of the cornea caused by fungi rather than bacteria or viruses. It is less common than bacterial keratitis but tends to be harder to diagnose and treat, and it can cause severe damage to vision if not managed promptly. The cornea is the clear front surface of the eye, and infection there clouds vision and causes pain.
Fungal keratitis is classically linked to eye injuries involving plant material, such as being struck by a branch or tree thorn, and to contact lens wear and certain eye drop misuse. Because antifungal treatment works slowly, this infection often needs weeks of intensive therapy under specialist care.
Fungi are widespread in the environment, in plants, soil, and decaying material, but they rarely infect a healthy eye. Infection usually requires the cornea's surface to be broken first, most often by an injury that drives fungal material into the tissue. This is why fungal keratitis is more common in warm, humid, agricultural regions and in people who work or spend time outdoors. It can be more difficult to recognize and treat than bacterial infection, so a low threshold for specialist referral is important, especially when an eye fails to improve after an injury involving vegetation.
Symptoms
Symptoms usually affect one eye and may develop more gradually than bacterial infection. They include:
- Eye pain, which may be out of proportion to how the eye looks early on
- Redness
- Blurred vision
- Sensitivity to light
- Watering and discharge
- A white, grey, or feathery-edged spot on the cornea
- A feeling of something in the eye
Symptoms that persist or worsen after an eye injury, especially one involving vegetation, are a warning sign and need urgent assessment. Fungal keratitis often progresses more slowly than bacterial infection, so an eye that gradually fails to improve, or worsens, over days after an injury should raise concern. The white spot on the cornea sometimes has feathery edges or smaller satellite spots nearby, features a doctor may recognize. Because the early stages can be mistaken for other infections, it is important to mention any recent contact with plants, branches, or soil when seeking care.
Causes
Fungal keratitis occurs when fungi enter and grow in the cornea. Common groups include filamentous fungi such as Fusarium and Aspergillus, and yeasts such as Candida.
- Eye injury with organic material: Trauma from plants, branches, thorns, or soil is the classic cause, especially in agricultural and outdoor settings.
- Contact lens wear: Poor hygiene, contaminated solution, or wearing lenses while swimming.
- Long-term steroid eye drops or a weakened immune system: These reduce the eye's defenses against fungal growth.
Risk Factors
- Eye injury involving plants, soil, or wood
- Outdoor or agricultural work
- Contact lens wear, especially with poor hygiene
- Long-term use of steroid eye drops
- A weakened immune system or diabetes
- Living in a warm, humid climate
Diagnosis
An ophthalmologist examines the eye with a slit lamp and looks for features suggestive of fungal infection, such as feathery edges or satellite lesions. Because fungal and bacterial infections can look similar, laboratory testing is important:
- A corneal scraping is sent for fungal culture and microscopy
- Special stains or molecular tests may be used
- In some centers, a microscope technique called confocal microscopy can show fungal elements directly
Diagnosis can take time, so treatment is sometimes started on clinical suspicion.
Treatment
Fungal keratitis requires specialist treatment and patience, as antifungal drugs act slowly.
- Antifungal eye drops: Frequent drops, such as natamycin, are the mainstay and may be needed for several weeks.
- Oral or injected antifungals: Added for deeper or more severe infections.
- Stopping contact lenses and reviewing steroid drops: Lenses are removed, and steroid drops are usually avoided as they can worsen fungal infection.
- Surgery: Severe, deep, or unresponsive cases may need a corneal transplant.
Patience is a central part of treatment. Antifungal drops penetrate the cornea slowly and the infection responds gradually, so improvement can take longer than people expect, and treatment is usually continued well beyond the point at which the eye starts to look better. Steroid drops are generally avoided because they can encourage fungal growth. Close, prolonged follow-up is essential because relapse can occur if treatment is stopped too soon or if dormant fungal elements remain. Working closely with a corneal specialist, who adjusts therapy based on how the eye responds, gives the best chance of clearing the infection and preserving vision.
Prevention
- Wear protective eyewear when gardening, farming, or doing outdoor work
- Seek prompt care for any eye injury, especially involving plants or soil
- Follow contact lens hygiene strictly and never swim or shower in lenses
- Use fresh lens solution and replace lenses and cases as directed
- Do not use steroid eye drops without medical guidance
When to See a Doctor
See an eye doctor urgently if you have:
- A red, painful eye that persists or worsens after an eye injury
- Blurred vision or a white spot on the cornea
- Symptoms that are not improving with standard treatment
- An eye injury involving a plant, branch, or soil
Early specialist care improves outcomes. Because fungal keratitis can mimic other infections, do not delay assessment if a treated eye is not getting better.
Frequently Asked Questions
How do you get fungal keratitis?
It most often follows an eye injury involving plant material, branches, or soil, which introduces fungi into the cornea. Contact lens misuse and long-term steroid eye drops are other important risk factors.
Why is fungal keratitis hard to treat?
Antifungal medicines penetrate the cornea slowly and act gradually, so treatment often lasts several weeks. Fungal infections can also extend deep into the cornea, sometimes requiring surgery.
Is fungal keratitis an emergency?
Yes. It can severely damage vision if untreated, so any persistent painful red eye, especially after an eye injury, should be assessed by an eye doctor without delay.
Can contact lenses cause fungal keratitis?
Yes. Poor lens hygiene, contaminated solution, and wearing lenses while swimming can allow fungi to infect the cornea. Strict lens care lowers this risk.
Will my vision recover?
Outcomes depend on how deep the infection is and how soon treatment starts. Early, prolonged antifungal treatment offers the best chance of recovery, though scarring or a corneal transplant is sometimes needed.
References
- American Academy of Ophthalmology. Fungal Keratitis.
- National Eye Institute (NEI). Keratitis.
- Centers for Disease Control and Prevention (CDC). Fungal Keratitis.
- MedlinePlus, U.S. National Library of Medicine. Corneal injuries and infections.