Fungal Keratitis (Corneal Fungal Infection)
Understanding Fungal Keratitis
Fungal keratitis occurs when fungal organisms penetrate the cornea and begin to grow. This usually happens after an eye injury, especially one involving plant material like a tree branch or thorn. The fungi enter through a break in the corneal surface and multiply in the tissue.
Contact lens wearers can also develop fungal keratitis when fungi contaminate their lenses or lens care solutions. Poor hygiene practices increase the risk of introducing these organisms into the eye.
Two main groups of fungi cause corneal infections. Filamentous fungi, including Fusarium and Aspergillus species, are common in warmer climates and often follow injuries from plants or soil. Yeast fungi, particularly Candida species, tend to occur in people with weakened immune systems or existing eye diseases.
The type of fungus influences how we treat the infection and how quickly you may recover. Laboratory testing helps us identify the specific organism so we can choose the most effective medication.
Several other eye conditions can mimic fungal keratitis, making accurate diagnosis essential. Bacterial keratitis is the most common look-alike and may appear nearly identical in the early stages. Acanthamoeba keratitis, often linked to contact lens wear and contaminated water, can cause severe pain out of proportion to clinical findings. Herpes simplex virus keratitis may also present with corneal infiltrates and inflammation. Sterile inflammatory infiltrates can occur without infection and may resolve without antifungal therapy. Because these conditions require different treatments, we rely on careful examination and laboratory testing to guide the appropriate approach.
Fungal infections can penetrate deep into the cornea and, in some cases, progress despite treatment. Without prompt care, the infection may destroy corneal tissue and cause permanent scarring. This scarring can blur your vision or lead to significant vision loss in the affected eye.
- The infection can perforate the cornea, creating a hole that threatens the entire eye
- Fungi may spread to other parts of the eye, including the anterior chamber or interior structures
- Delayed or inadequate treatment increases the likelihood of needing a corneal transplant
- In rare cases of uncontrolled infection spreading throughout the eye, removal of the eye may be necessary to prevent further complications
Bacterial and fungal eye infections can look similar at first, but they require completely different treatments. Fungal infections typically develop more gradually and may not respond to the antibiotic drops we prescribe for bacterial keratitis. The white or gray infiltrate in the cornea often has feathery edges in fungal cases, unlike the more defined borders seen with bacteria.
Fungal keratitis is also much harder to cure because fungi have protective cell walls that resist many medications. Treatment takes weeks or months instead of days, and the risk of treatment challenges is higher.
Recognizing Symptoms and Warning Signs
The first signs of fungal keratitis often develop gradually over days or weeks. You may notice mild irritation or the feeling that something is in your eye. Your eye might water more than usual, or you may see slight redness. These early symptoms are easy to mistake for less serious problems, which is why any persistent eye discomfort after an injury or contact lens use requires evaluation.
Some people ignore mild symptoms, hoping they will improve on their own. However, early diagnosis greatly improves your chances of a full recovery without permanent damage.
As the infection progresses, eye pain becomes more intense. The pain may feel sharp, aching, or throbbing, and it often worsens when you blink or move your eye. Many patients describe the discomfort as severe enough to interfere with sleep and daily activities.
Light sensitivity, called photophobia, also increases as the cornea becomes more inflamed. You may need to wear sunglasses indoors or keep your eyes closed in normal lighting. This sensitivity signals that the infection is affecting the deeper layers of your cornea.
Fungal keratitis causes progressive blurring of vision in the affected eye. You might notice that objects appear hazy or that you cannot focus clearly, even with your glasses or contact lenses. The blurriness results from corneal swelling and the infiltrate of inflammatory cells and fungi blocking light from entering your eye properly.
- Your vision may fluctuate throughout the day
- Colors might appear less vivid or washed out
- You may see halos around lights, especially at night
- Reading and detailed tasks become difficult or impossible
Your eye may produce tearing or mild discharge, though heavy discharge is less common with fungal infections than with bacterial infections. The white of your eye becomes increasingly red as blood vessels respond to the infection. If you look closely in a mirror, you might see a white or grayish spot on the colored part of your eye, which is actually the infected area on your cornea.
These visible changes indicate active infection and inflammation. The white spot represents a collection of fungi, inflammatory cells, and damaged corneal tissue. We can often see this infiltrate during your examination with our specialized microscope.
Seek emergency eye care if you experience sudden severe pain, rapid vision loss, or symptoms that worsen quickly despite using eye drops. Any eye injury involving plants, soil, or contaminated water should be evaluated promptly, even if symptoms seem mild at first.
Contact lens wearers who develop eye pain, redness, or vision changes while wearing lenses or shortly after removing them should stop lens use immediately and contact our office. These symptoms may indicate a developing infection that requires urgent attention.
If you suspect a corneal infection, certain actions can worsen the problem or delay proper treatment. Protecting your eye until we can evaluate you is essential for the best outcome.
- Do not use leftover steroid eye drops or combination antibiotic-steroid drops unless directed by an ophthalmologist, as steroids can worsen fungal infections
- Do not patch the eye or wear a bandage contact lens unless specifically instructed
- Do not continue wearing contact lenses in either eye
- Do not rinse the eye with tap water or other non-sterile solutions
Who Is at Risk for Fungal Keratitis
Contact lens wearers face increased risk, especially if they sleep in their lenses, swim or shower while wearing them, or fail to clean and replace lenses as directed. Using tap water to rinse lenses or lens cases introduces organisms that can cause infection. Extended wear lenses and improper storage create environments where fungi can grow.
- Wearing lenses longer than recommended increases corneal trauma
- Topping off old solution instead of emptying and refilling the case allows contamination to build up
- Sleeping in lenses not designed for overnight wear is a major risk factor for all types of microbial keratitis
- Not washing hands before handling lenses transfers organisms to the eye
- Using homemade saline solutions introduces unsterile water and fungi
- Failing to replace the lens case regularly allows biofilm and organisms to accumulate
Trauma to the eye from vegetation is one of the most common causes of fungal keratitis. A scratch from a tree branch, thorn, or leaf can introduce fungal spores directly into the cornea. Even minor injuries during gardening, farming, or outdoor work can lead to serious infections.
The risk is highest in agricultural workers and people who spend significant time outdoors. Wearing protective eyewear during yard work, farming, and similar activities can prevent many of these injuries.
People with compromised immune systems are more vulnerable to fungal infections. Conditions like diabetes, HIV, or cancer can reduce your body's ability to fight off fungi. Medications that suppress the immune system, including steroids and chemotherapy drugs, also increase risk.
Pre-existing ocular surface diseases pose additional risk. Chronic dry eye, neurotrophic keratopathy, prior herpes simplex keratitis, and corneal surface irregularities can make it easier for fungi to invade the cornea. Long-term use of topical corticosteroid or immunomodulator eye drops may increase susceptibility and can mask early infection symptoms, allowing fungi to grow unchecked.
Fungal keratitis occurs more frequently in tropical and subtropical regions with warm, humid climates. These conditions favor fungal growth in the environment, increasing exposure risk. However, cases can occur anywhere, particularly during warmer months.
In the United States, southern states report higher rates of fungal keratitis than northern regions. International travel to tropical areas may also expose you to different fungal species not commonly found in your home region.
How We Diagnose a Corneal Fungal Infection
We begin by asking about your symptoms, recent eye injuries, and contact lens habits. Your history helps us determine whether fungal keratitis is likely. We then examine your eye using a slit lamp, a specialized microscope that allows us to see the cornea in detail with bright light and magnification.
During this examination, we look for characteristic signs of fungal infection, including the pattern and depth of the corneal infiltrate. We also check your eye pressure and assess whether the infection has spread to other eye structures.
To confirm the diagnosis and identify the specific fungus, we need to collect a sample from your cornea. We numb your eye with drops and use a tiny blade or spatula to gently scrape cells from the infected area. This procedure sounds uncomfortable but typically causes minimal discomfort because your eye is well numbed, though you may feel some pressure.
- The sample is sent to a laboratory for culture and staining
- Technicians grow the fungi in special media to identify the species
- Staining techniques allow immediate microscopic examination of the sample
- Results help us choose the most effective antifungal medication
- If you wear contact lenses, we may ask you to bring in your lens, case, and solution for culture as well
- If initial tests are negative but suspicion remains high, we may perform repeat scrapings or consider corneal biopsy or specialized molecular testing
In some cases, we may recommend confocal microscopy, an advanced imaging technique available in specialized centers that allows us to see living corneal cells and fungal structures in real time without removing tissue. This painless procedure may help confirm the diagnosis quickly when available and can assist in monitoring treatment response in selected cases.
Anterior segment optical coherence tomography may also show us the depth of the infection and whether it threatens to perforate the cornea. These imaging tools complement traditional testing and help us plan the most appropriate treatment.
Unlike bacterial infections where preliminary culture results often come back within a few days, fungal cultures can take days to weeks to grow, and final identification may take even longer. Fungi multiply slowly in laboratory conditions, so we must wait patiently for enough growth to identify the organism accurately. We often start treatment before culture results return, based on our clinical examination and initial microscopic findings.
This delay can feel frustrating when you are in pain and worried about your vision. However, rushing the diagnosis or treating without proper testing can lead to treatment failure and worse outcomes.
Treatment Approaches for Fungal Keratitis
We typically start treatment with topical antifungal eye drops applied directly to the infected eye. Natamycin is often the preferred first-line agent for filamentous fungal infections because it works well for superficial and anterior stromal ulcers caused by common fungal species. You may need to use drops as frequently as every hour around the clock during the initial phase of treatment.
Natamycin has limited penetration into the deeper cornea, so for infections extending into the deep stroma, we may add or switch to other agents. For yeast infections, we may prescribe amphotericin B drops or azole antifungals depending on culture results. The high frequency of drop use is essential because the medication must maintain constant contact with the infected tissue to work effectively.
Topical voriconazole, often prepared by compounding pharmacies, may be used as an alternative or adjunct, particularly for deep infections or when initial therapy is not adequate. Therapy is guided by the results of corneal smears and cultures, and we adjust treatment based on your clinical response.
When the infection is deep or severe, we may add oral antifungal medications to your treatment plan. These pills work from inside your body to fight the infection throughout the cornea and potentially prevent spread to other eye structures. Common oral antifungals include azoles like voriconazole or fluconazole, chosen based on the fungal species and your overall health.
Systemic therapy is often considered for ulcers with deep stromal involvement, extension toward the sclera or limbus, or when there is concern for spread into the anterior chamber or other intraocular structures. The choice of agent depends on the identified organism, the severity and location of infection, and individual patient factors such as kidney and liver function.
- Oral medications require monitoring of liver function with blood tests
- Side effects may include nausea, headache, or skin rashes
- You must take pills at the same times each day for best results
- Drug interactions with other medications need careful review
Severe fungal keratitis may require admission to the hospital for intensive treatment. We recommend hospitalization when you cannot reliably administer hourly eye drops at home, when the infection threatens to perforate the cornea, when close monitoring is essential, or when severe pain or poor follow-up reliability makes outpatient care unsafe. Intravenous antifungal therapy is generally reserved for cases with suspected spread into the eye beyond the cornea or systemic involvement, which is uncommon in isolated keratitis.
During your hospital stay, nurses will help administer your frequent eye drops and monitor for complications. We will examine your eye daily or even more often to track treatment response and watch for signs of worsening infection.
When medications cannot control the infection or when the cornea is too damaged to heal properly, we may recommend a corneal transplant. Therapeutic penetrating keratoplasty is a procedure performed to save the eye and halt the infection by removing infected tissue and replacing it with healthy donor cornea. This is distinct from later optical keratoplasty, which may be performed after the infection has resolved to restore vision. We perform transplants during active infection only when necessary to control the disease and preserve the eye, as the risk of rejection and recurrent infection is higher.
In many cases, we prefer to control the infection first with medical therapy and then perform transplant surgery later to restore vision after the eye has healed. This staged approach generally has better outcomes for both infection control and visual rehabilitation, though emergency transplant may be needed if the cornea perforates.
Depending on the specifics of your case, we may recommend additional interventions to improve treatment success. In selected cases, gentle removal of the corneal epithelium can enhance antifungal drug penetration and reduce the burden of organisms on the surface. For infections that do not respond adequately to topical and oral therapy, we may consider intrastromal or intracameral antifungal injections, though these techniques are not universally available and are used based on individual clinical judgment.
We may also prescribe cycloplegic eye drops to reduce pain and control inflammation inside the eye. If increased eye pressure develops as a complication, pressure-lowering drops may be necessary. Unless we specifically direct otherwise, eye patches and bandage contact lenses are generally avoided during active infection.
Fungal keratitis treatment requires patience and persistence. Most patients require at least six to eight weeks of intensive antifungal therapy, and some cases need months of treatment. The frequency of eye drops gradually decreases as the infection improves, but stopping treatment too early allows the fungi to regrow and the infection to return.
We will monitor your progress with regular examinations and, in some cases, repeat cultures to help assess response. Even after the infection resolves, you may need to continue drops at a reduced frequency for several more weeks to prevent recurrence.
Fungi have tough cell walls and sophisticated defense mechanisms that make them resistant to many medications. Antifungal drugs often penetrate the cornea less effectively than antibiotics, requiring higher doses and more frequent application. Fewer antifungal medications are available compared to antibiotics, limiting our treatment options.
Additionally, fungi can survive in a dormant state within corneal tissue, hiding from medications and your immune system. This ability to persist makes recurrence possible if treatment is not completed fully. The slow growth of fungi also means treatment response takes longer to see compared to bacterial infections, which may improve within days.
Recovery, Home Care, and Follow-Up
The recovery process is gradual and requires patience. In the first few weeks, you may notice some improvement in pain and redness, but vision often remains blurry due to corneal swelling and scarring. As treatment continues and inflammation decreases, your comfort level should improve significantly.
Even after the infection clears, corneal scarring may affect your vision. Some patients regain excellent vision, while others have residual blurriness that may require glasses, specialty contact lenses, or eventual corneal transplant to correct. Your final visual outcome depends on infection severity, how quickly treatment started, and how well the infection responded to medication.
Proper medication use is critical to your recovery. Wash your hands thoroughly before applying eye drops, and avoid touching the dropper tip to your eye or any surface to prevent contamination. Tilt your head back, pull down your lower eyelid, and place the drop in the pocket between your eyelid and eye. Close your eye gently for a minute without blinking hard to allow the medication to absorb.
- Set alarms or reminders to help you remember frequent dosing schedules
- Store medications as directed, refrigerating some drops if required
- If you are using multiple types of drops, apply them in the order we specify and wait at least five minutes between different medications
- Never share your eye drops with others or use expired medications
During treatment, avoid swimming, hot tubs, and any activities that expose your eye to water or dirt. Do not wear contact lenses in either eye until we confirm the infection has completely resolved and your cornea has healed. Future contact lens wear in the affected eye depends on the degree of healing and scarring. Some patients can resume lens wear after proper refitting, sometimes with rigid gas permeable or scleral lenses, while others may need to discontinue use long term.
Protect your eye from further injury by avoiding dusty or dirty environments when possible. Wear protective eyewear if you must work outdoors or in situations where debris could enter your eye. Avoid rubbing or touching your infected eye, as this can spread the infection or cause additional damage to the fragile healing cornea.
- Discard all current contact lenses, lens cases, and opened lens solution to eliminate sources of contamination
- Avoid wearing eye makeup until cleared by your eye doctor
- Do not drive if your vision is significantly impaired
- Use protective eyewear or sunglasses when outdoors
We will schedule frequent follow-up visits, often every few days initially, to monitor your infection and adjust treatment as needed. During these appointments, we examine your cornea carefully to assess healing and watch for complications. In some cases, we may perform repeat corneal scrapings to help guide ongoing therapy decisions.
As you improve, visits become less frequent, but regular monitoring continues for weeks or months. Missing appointments can lead to undetected treatment problems or recurrence. Even after treatment ends, we typically recommend periodic check-ups to ensure the infection does not return and to address any vision problems caused by scarring.
Call our office immediately if your pain suddenly worsens, your vision decreases significantly, or you develop new symptoms. Increased redness, swelling, or discharge may indicate treatment challenges or a secondary infection. If you see new white or dark spots on your cornea, this could signal worsening or spreading infection.
Watch for signs that may suggest spread of infection into the eye or impending perforation. New floaters, marked worsening of light sensitivity with vision loss, or increasing pain despite treatment should prompt immediate contact. A new layer of white material settling at the bottom of your vision, rapid expansion of the infected area, sudden fluid leakage from the eye, sudden flattening or change in eye shape, or dramatic vision drop all require emergency evaluation. Trust your instincts and contact us if something does not feel right, even if you cannot pinpoint a specific concerning symptom.
Frequently Asked Questions
Yes, fungal keratitis can result in permanent vision impairment if not treated promptly and appropriately. Scarring from the infection may create cloudy areas in your cornea that block or distort light. However, early diagnosis and proper treatment greatly improve your chances of preserving useful vision, and many patients recover with good visual outcomes.
Following strict hygiene practices significantly reduces your risk. Always wash and dry your hands before handling lenses, replace them according to the recommended schedule, and use only fresh sterile solution to clean and store them. Never rinse lenses or cases with tap water, never reuse or top off old solution, avoid sleeping in lenses unless specifically designed for overnight wear, and remove lenses immediately if your eyes become irritated or red. Replace your lens case every three months and discard any opened solution after the recommended period.
No, you cannot spread fungal keratitis to other people through casual contact. The infection requires fungi to enter the cornea through a wound or contaminated contact lens. However, sharing contact lenses, eye makeup, or towels could theoretically transfer contaminated material, so avoid sharing personal eye care items.
A simple corneal abrasion is a surface scratch that typically heals within a few days without infection. Fungal keratitis involves active infection with organisms growing in the corneal tissue, causing progressive tissue damage rather than healing. While both conditions cause pain and blurred vision initially, fungal keratitis worsens over time and produces characteristic white infiltrates that do not appear with simple scratches. A scratch may occasionally become the entry point for fungal infection, which is why injuries from plant material require close monitoring.
No, over-the-counter products cannot cure fungal keratitis. Lubricating drops or redness relievers will not kill fungi and may delay proper treatment, allowing the infection to worsen. Prescription antifungal medications specifically formulated to penetrate the cornea and target fungal organisms are required to treat this serious condition effectively.
Many patients recover with medication alone and do not require surgery. We reserve surgical intervention for cases where medical treatment does not adequately control the infection, where additional measures are needed to save the eye, or where severe scarring prevents functional vision after the infection clears. Your individual need for surgery depends on infection severity, treatment response, the presence of complications, and final visual outcome after healing.
Getting Help for Fungal Keratitis
If you experience eye pain, redness, vision changes, or any symptoms of possible fungal keratitis, contact our office right away for evaluation. Early diagnosis and treatment offer the best chance for preserving your vision and avoiding serious complications.