Fungal Keratitis

What is Fungal Keratitis?

Microbial keratitis is an infection of the cornea, the clear, dome-shaped surface that covers the front of your eye. It can arise from various things like bacteria, viruses, fungi, or protozoa. Fungal keratitis, a specific type of infection caused by fungus, accounts for approximately half of all microbial keratitis cases. This infection dates back to 1879 and has become more common over the last 30 years.

Fungal keratitis is a serious condition that needs swift and effective treatment. If left untreated, it can cause severe damage to the cornea and even lead to a more severe eye infection known as endophthalmitis, which can result in a significant loss of vision. Early diagnosis and management of the condition are critical to prevent these severe, long-term complications, including blindness.

There are over 100 types of fungus that have been identified as possible causes of fungal keratitis. The most common fungus responsible for these infections can vary depending on where you live. Around 40% of these fungal infections occur as a result of an injury.

There are also two main groups of fungus, known as yeast and filamentous fungi, that both contribute to fungal keratitis. The specific type of fungus causing the infection can depend on several factors like the person’s health, the weather, climate conditions, location, and the level of crowdedness in their area.

Fungal keratitis is often linked to certain risk factors like injury, having a weak immune system, having a disease that affects the surface of the eye, or wearing contact lenses. These risk factors not only increase your risk of getting fungal keratitis, but also make you more likely to get other types of fungal infections. It’s important to understand that this condition can affect people in many different ways.

Diagnosing fungal keratitis can be tricky in a clinical setting, which often results in delays in getting confirmed results. That’s why it’s incredibly important to consider the possibility of fungal keratitis, especially if you have any known risk factors. Additionally, managing the conditions can be difficult because many antifungal medications have a hard time penetrating the cornea adequately.

What Causes Fungal Keratitis?

Fungal keratitis is an infection of the cornea (the clear, front surface of your eye) caused by different types of fungi. The most common culprits are Fusarium, Aspergillus, and Candida. The exact type of fungus causing the infection can depend on a few things, like where you live. This is because the local weather, climate, and how urbanized the area is can affect which types of fungi are around.

In India, for instance, studies have found that the Aspergillus fungus is the most common cause of fungal keratitis. This fungus was found to cause over half of all the cases. Conversely, in other parts of the world like Southern India and the U.S, Fusarium is often the main cause. In the U.S, Fusarium was found to cause 39% of the cases, while yeasts like Candida caused 22%. Over in central and northern China, Fusarium was also the most common, making up over half of the cases.

Interestingly though, in the U.K, researchers found that Candida was the most common cause, causing 57% of the fungal keratitis cases. This means the specific cause of fungal keratitis can vary a lot depending on where you live.

Some things about your lifestyle can also put you at more risk of getting certain types of fungal keratitis. For example, people who suffer eye injuries or who wear contact lenses are more likely to get Fusarium keratitis. On the other hand, people with existing eye conditions or who use steroid eye drops are more likely to get Candida keratitis. You can also get fungal keratitis from an injury caused by plant material, which can introduce fungi into your eye.

It also appears that people who work in agriculture are more likely to get fungal keratitis. Poor personal hygiene and wearing contact lenses overnight can increase your risk as well.

If you’ve had eye surgery recently, like LASIK (a surgery that corrects vision problems), you might also have a small chance of getting fungal keratitis. This could happen if the operating room wasn’t cleaned properly, or if your eye wasn’t looked after properly afterwards. In these cases, a few different types of fungi like Candida, Fusarium, Aspergillus, and Alternaria can cause the infection.

Different types of fungus are categorized differently when causing keratitis. Yeast such as Candida species. Filamentous septate which are divided into non-pigmented (like Fusarium and Aspergillus) and pigmented types (like Cladosporium, Curvilaria, Alternaria, Lasiodiplodia). There’s also filamentous non-septate type, represented by fungi like Mucor and Rhizopus.

Risk Factors and Frequency for Fungal Keratitis

Fungal keratitis is an infection of the eye which can be influenced by where you live, your economic status and the environment. It’s more common in warmer places, like Florida. However, colder northern areas in the United States see fewer cases of this condition. There are different types of fungi that can cause fungal keratitis. In the US, the most common ones are Fusarium, Candida, and Aspergillus. In India, Aspergillus is most common.

Interestingly, fungi like Fusarium and Aspergillus are usually found in warmer climates, particularly in cases arising from injuries. In fact, in Brazil, fungus has been found in 67% of fungal keratitis cases, with 10.5% attributed to Aspergillus and 10% to Candida.

In older and weaker individuals, and those with a compromised immune system in the US, fungal keratitis is more commonplace. Candida is the main culprit here.

Fungal keratitis is more prevalent in some parts of the world than others. There were 1360 cases in a decade in India (Hyderabad), 2065 cases in 9 years in Central China, but only 56 instances over 8 years in Melbourne, Australia and 61 eyes affected over a 16-year period in New York.
These differences are likely due to changes in climate, environmental factors, work patterns, or individual behavior.

Contact lens use increases the risk of fungal keratitis, particularly if the lenses are not properly cared for. 45 million people in the US use contact lenses and over 80% engage in risky behaviors, such as sleeping with the lenses in and cleaning them with tap water.

Between 2005 and 2006, there was a major outbreak of Fusarium keratitis in the US and in several other countries. This form of the infection was later linked to a specific brand of multi-purpose contact lens cleaning solution. It highlights the importance of carefully monitoring these products to help prevent future eye infections associated with contact lenses.

A number of studies have shown that young adult males are more likely to suffer from fungal keratitis, possibly because they spend more time outdoors and are more likely to have accidents. In a detailed Chinese study, more than 60% of patients with fungal keratitis were males, and over 75% were aged between 30 and 60.

Signs and Symptoms of Fungal Keratitis

Fungal keratitis is an eye condition that may present differently depending on the type of fungus causing it, such as filamentous fungus or yeast. Several factors may point to the possibility of this condition. For instance, the patient’s history might reveal incidents of eye trauma involving plant material, foreign bodies, soil, or dust. People who work in fields or farms or those who wear contact lenses could also be more susceptible to fungal keratitis.

Medical history could also reveal conditions or habits that increase the likelihood of developing fungal keratitis. These include:

Prior eye surgeries
Corneal transplants
Alcohol consumption
Malnourishment
Chronic conditions such as HIV, hepatitis, diabetes
Steroid use
Treatment that suppresses the immune system

There’s another similar condition called Pythium keratitis, which will have to be ruled out. This condition tends to relate to eye injuries involving mud or clay.

Common symptoms of fungal keratitis can include blurred vision, pain, redness, discharge from the eye, a feeling of grittiness, light sensitivity, excessive tearing, and involuntary closure of the eyelid. It’s crucial to note that in fungal keratitis, visible signs are often more pronounced than symptoms, unlike bacterial keratitis where symptoms are more noticeable.

When examining the eye for signs of fungal keratitis, a preliminary check will involve looking for common indicators such as swollen eyelids, twitching eyelid, eye discharge, and inflammation around the eyelids. A more detailed examination under a special light can reveal additional signs, including inflammation of the eyelid edges, discharge from the eye, changes in the eye’s white part, surface defects in the cornea, unusual margins around the cornea, thinning of the cornea, and pus in the eye’s front chamber.

There are also specific signs associated with the type of fungus involved. For instance, when filamentous fungi cause fungal keratitis, the patient often has a history of trauma with plant material. The affected eyes usually have an ulcer with firm discharge and lines of fungus extending beyond the ulcer’s borders. On the other hand, when yeast fungi cause keratitis, there may be a history of ocular surface disease or immunosuppression. Clinically, it may resemble bacterial keratitis but progress more gradually. However, it could be challenging to predict the exact fungal species involved based on clinical signs alone.

Also note that Candida-induced keratitis typically appears as a dense, yellow-white infiltration. In contrast, filamentous fungus-induced keratitis looks gray or yellow-white with blurry edges. Eye inflammation and infection in the innermost layer of the eyeball can also occur as complications, often appearing at later stages.

Testing for Fungal Keratitis

If a fungal keratitis infection (a fungal infection in the eye) is suspected, there are multiple tests your doctor might use to diagnose it. One of the first steps is to collect a tissue sample; this might involve scraping the surface of your eye or taking a biopsy. This sample is then examined under a microscope using different types of stains. One of the most effective of these stains is a 10% KOH preparation, while others like Gram and Giemsa staining are only around 50% effective in detecting the fungus. It’s essential to take a sufficiently deep sample from the eye, as swabbing is often not enough to confirm a fungal infection.

In certain cases, a test called polymerase chain reaction (PCR) is used. This allows for a very quick and precise identification of the fungus causing the infection. However, this test can sometimes misidentify non-harmful organisms as the cause. PCR testing can be done on small samples of eye tissue or fluids such as tears, but it requires specialized and expensive equipment which may not always be available.

Another test used to diagnose fungal infections is the beta-D-glucan test. This test detects a component of the cell wall found in many types of fungi in the bloodstream. If the fungal infection has spread to the bloodstream, this test may be much quicker and more sensitive than traditional cultures.

In some hard-to-diagnose cases, an anterior chamber tap might be necessary. This is a procedure where fluid is drained from the front part of the eye, which can be useful if there’s evidence of fungal infiltration.

Non-invasive imaging techniques such as confocal microscopy and anterior segment optical coherence tomography (AS-OCT) can also be used. These methods can help in visualizing the infection in the eye without any need for a tissue sample. Confocal microscopy can reveal branching white lines in the area of the eye where the infection is. AS-OCT can detect early signs of necrotic (dead) tissue in the eye.

Lastly, ophthalmic B-scan ultrasonography can aid in diagnosing and monitoring the progress of the infection, particularly if the infection has spread and is impairing the doctor’s ability to examine the eye.

Treatment Options for Fungal Keratitis

Specific patient groups, like older patients who cannot self-administer medications or patients with advanced fungal keratitis, may need to be admitted to a hospital for treatment. In these situations, it is crucial to stop using contact lenses immediately.

For patients who are at risk of or experiencing a rupture of their eye (a perforation), key steps include applying a pad, bandage, and antibiotic ointment for protection. An additional clear plastic eye shield can also be used in between the administration of eye drops.

In mild cases of cornea infection, less aggressive treatment and a moderate use of antifungal eye drops may be enough. However, managing other health conditions like diabetes and avoiding contact lens use is crucial. When waiting for lab results, it’s necessary to start treatment to prevent the ulcer from worsening.

As part of the treatment, the doctor might regularly remove mucus and dead tissue to increase the effectiveness of antifungal medicines. All the current antifungal medicines slow down the growth of fungus rather than killing it; it can take quite a while for your body to completely get rid of the fungal organism.

Various antifungal medicines are used in the treatment, like Natamycin, which is the first choice for managing most fungal keratitis, especially fungal infections with filamentous fungi. Amphotericin B is the preferred treatment for yeast infections, while Voriconazole can penetrate better into the eye and may be a better alternative to Natamycin. These medicines are usually given as eye drops that are administered every hour for the first 48 hours of treatment, and then reduced depending on how well the treatment is working.

In extreme situations, injections of antifungal medicines might be used. Particularly for patients who have trouble adhering to treatment or have severe keratitis.

In cases of severe and progressing ulcers, certain infections may need systemic treatment. This can take the form of intravenous medicines like Amphotericin B, or oral medicines like Voriconazole or Fluconazole.

To continue with therapy doctors ideally want to see signs like a decrease in pain, the size of the inflamed area and inflammation in the front section of the eye. The slow healing of the skin covering the lesion is also a good sign.

In cases of non-responsive treatment, if an ulcer penetrates all the way through the cornea, or if the infection proves resistant to conventional therapies, further measures might be necessary. These can involve washing the anterior chamber of the eye if there is evidence of an excess of pus or cloudy exudates, or even injections of Voriconazole directly into the cornea.

Some other therapeutic options include a superficial removal of the cornea (a superficial keratectomy) to effectively reduce the size of the ulcer, or a transplant of the cornea (a therapeutic keratoplasty) if medical therapy doesn’t work. However, these procedures carry a risk of complications, such as a recurrence of the infection, endophthalmitis (inflammation inside the eye), and rejection of the transplant.

In extreme cases, the eye may need to be removed (enucleation) if it becomes blind and painful with uncontrolled inflammation. In cases where the healing of fungal keratitis results in a scarred and opaque cornea, a penetrating or lamellar keratoplasty can be performed to restore visual acuity.

When trying to diagnose fungal keratitis, doctors need to consider and rule out the following similar conditions:

Bacterial keratitis
Pythium keratitis
Viral keratitis
Neurotrophic keratitis
Acanthamoeba keratitis
Necrotizing herpetic keratitis
Exposure keratopathy

These conditions could present similar symptoms, so it’s important for the doctor to distinguish between them accurately.

What to expect with Fungal Keratitis

The outcome for someone with a fungal infection in the eye, or what doctors call “fungal keratitis”, depends on a few things. These factors include: what kind of fungus caused the infection, how deep and widespread the infection is, whether there are any complications, and how quickly treatment started.

Some patients can get better by using antifungal eye drops, while others might need a surgical procedure called a therapeutic keratoplasty.

There’s a part of the eye called the “Descemet membrane”, which is located in the innermost layer of the cornea near the aqueous humor, that helps protect the eye from bacteria. However, certain types of fungus can get through this barrier and lead to a serious condition called endophthalmitis.

About 30% of fungal eye infections may not get better with medication, and this sometimes can lead to a tear or hole in the cornea, known as corneal perforation.

After a successful treatment, the center of the cornea may become scarred and turn cloudy, which could affect someone’s vision. They may need a surgical procedure known as keratoplasty to improve their vision.

Possible Complications When Diagnosed with Fungal Keratitis

Some unpleasant side effects can occur as a result of fungal keratitis, such as:

Unhealed damage to the surface of the eye
Breakdown of the cornea (corneal perforation)
Corneal melting
Corneal scarring
Secondary glaucoma, a type of eye disease causing vision loss
Iris neovascularization, or new blood vessels forming in the colored part of your eye
Peripheral anterior synechiae, abnormal tissue adhesions in the eye
Posterior synechiae, when the Iris sticks to the lens of the eye
Scleritis, or inflammation of the white part of the eye
Endophthalmitis, an inflammation of the inside of your eye
Panophthalmitis, a severe inflammation affecting all layers of the eye
Complicated cataract, a type of clouding of the natural lens of the eye
Vitritis, inflammation of the jelly-like substance in your eye
Vitreous membranes
Permanent blindness
Phthisis bulbi, a shrunken, non-functional eye
Atrophic bulbi, a degenerative eye condition

Recovery from Fungal Keratitis

After undergoing keratoplasty, a surgical procedure to repair or replace parts of the cornea in your eye, you will require careful and consistent care, and regular check-ups. Just after the procedure, it is recommended you begin using antifungal eye drops, usually six times a day, along with other prescribed medications. After the procedure, you should come in for follow-up appointments on days 1, 5, 14, 21, and 28. Afterwards, visits should happen every two weeks or months based on your recovery and your doctor’s judgment.

Topical steroids, a type of anti-inflammatory medication for your eye, generally start 3 to 4 weeks after the procedure, depending on your recovery progress. If there’s no sign of infection on the corneal culture reports taken before and during the procedure, you can start using steroids three weeks after the surgery. But if the reports show infection, you’d need to wait a week longer, starting the steroids four weeks after the procedure.

It’s very important to understand the importance of having regular check-ups and consistently taking your medications as directed. You should be aware of the potential complications that can occur with a keratoplasty and the chances of successful recovery specific to your situation. You should be ready for the fact that you might need to undergo another keratoplasty, though it’s important to note that the success rate can decrease with each additional procedure.

Preventing Fungal Keratitis

Doctors will explain how patients can use contact lenses safely, and how to clean them properly to lower the risk of infections in the cornea (transparent front part of the eye) associated with contact lenses. It’s crucial for patients to maintain good hygiene, such as washing hands thoroughly before touching their contact lenses and refraining from wearing them overnight.

Frequently asked questions

Fungal keratitis is a serious infection of the cornea caused by fungus. It can lead to severe damage to the cornea and even result in a loss of vision if left untreated. There are over 100 types of fungus that can cause fungal keratitis, and the specific type of fungus can vary depending on various factors.

Fungal keratitis is more prevalent in some parts of the world than others.

Common signs and symptoms of Fungal Keratitis include: - Blurred vision - Pain in the affected eye - Redness of the eye - Discharge from the eye - Feeling of grittiness in the eye - Light sensitivity - Excessive tearing - Involuntary closure of the eyelid It is important to note that in Fungal Keratitis, visible signs are often more pronounced than symptoms, unlike bacterial keratitis where symptoms are more noticeable. When examining the eye for signs of Fungal Keratitis, common indicators to look for include swollen eyelids, twitching eyelid, eye discharge, and inflammation around the eyelids. A more detailed examination under a special light can reveal additional signs such as inflammation of the eyelid edges, changes in the eye's white part, surface defects in the cornea, unusual margins around the cornea, thinning of the cornea, and pus in the eye's front chamber. Specific signs associated with the type of fungus involved may also be present. For example, when filamentous fungi cause Fungal Keratitis, there is often a history of trauma with plant material. The affected eyes usually have an ulcer with firm discharge and lines of fungus extending beyond the ulcer's borders. On the other hand, when yeast fungi cause keratitis, there may be a history of ocular surface disease or immunosuppression. Clinically, it may resemble bacterial keratitis but progress more gradually. However, it could be challenging to predict the exact fungal species involved based on clinical signs alone. In addition, Candida-induced keratitis typically appears as a dense, yellow-white infiltration, while filamentous fungus-induced keratitis looks gray or yellow-white with blurry edges. Complications such as eye inflammation and infection in the innermost layer of the eyeball can also occur at later stages of Fungal Keratitis.

You can get Fungal Keratitis through various ways, such as eye injuries, wearing contact lenses, poor personal hygiene, working in agriculture, and having eye surgery.

The doctor needs to rule out the following conditions when diagnosing Fungal Keratitis: - Bacterial keratitis - Pythium keratitis - Viral keratitis - Neurotrophic keratitis - Acanthamoeba keratitis - Necrotizing herpetic keratitis - Exposure keratopathy

The types of tests that may be needed to diagnose Fungal Keratitis include: 1. Tissue sample collection: This involves scraping the surface of the eye or taking a biopsy, which is then examined under a microscope using different types of stains such as 10% KOH preparation, Gram staining, and Giemsa staining. 2. Polymerase chain reaction (PCR) testing: This test allows for quick and precise identification of the fungus causing the infection, but it may sometimes misidentify non-harmful organisms as the cause. 3. Beta-D-glucan test: This test detects a component of the cell wall found in many types of fungi in the bloodstream, and it may be quicker and more sensitive than traditional cultures if the infection has spread to the bloodstream. 4. Anterior chamber tap: This procedure involves draining fluid from the front part of the eye and can be useful if there is evidence of fungal infiltration. 5. Non-invasive imaging techniques: Confocal microscopy and anterior segment optical coherence tomography (AS-OCT) can help visualize the infection in the eye without the need for a tissue sample. Confocal microscopy can reveal branching white lines in the infected area, while AS-OCT can detect early signs of necrotic tissue. 6. Ophthalmic B-scan ultrasonography: This test can aid in diagnosing and monitoring the progress of the infection, particularly if it has spread and is impairing the doctor's ability to examine the eye.

Fungal keratitis can be treated through various methods depending on the severity of the infection. In mild cases, less aggressive treatment and moderate use of antifungal eye drops may be sufficient. However, it is important to manage other health conditions like diabetes and avoid using contact lenses. For more severe cases, hospital admission may be necessary, and treatment may involve the use of antifungal eye drops, injections of antifungal medicines, or systemic treatment with intravenous or oral medicines. Regular removal of mucus and dead tissue may also be done to enhance the effectiveness of antifungal medicines. In extreme cases, additional measures such as washing the anterior chamber of the eye or surgical procedures like superficial keratectomy or corneal transplant may be required.

The side effects when treating Fungal Keratitis include: - Unhealed damage to the surface of the eye - Breakdown of the cornea (corneal perforation) - Corneal melting - Corneal scarring - Secondary glaucoma, a type of eye disease causing vision loss - Iris neovascularization, or new blood vessels forming in the colored part of your eye - Peripheral anterior synechiae, abnormal tissue adhesions in the eye - Posterior synechiae, when the Iris sticks to the lens of the eye - Scleritis, or inflammation of the white part of the eye - Endophthalmitis, an inflammation of the inside of your eye - Panophthalmitis, a severe inflammation affecting all layers of the eye - Complicated cataract, a type of clouding of the natural lens of the eye - Vitritis, inflammation of the jelly-like substance in your eye - Vitreous membranes - Permanent blindness - Phthisis bulbi, a shrunken, non-functional eye - Atrophic bulbi, a degenerative eye condition

The prognosis for fungal keratitis depends on several factors, including the type of fungus causing the infection, the depth and extent of the infection, the presence of complications, and the timeliness of treatment. Some patients can be treated with antifungal eye drops, while others may require a therapeutic keratoplasty surgical procedure. In some cases, the infection may not improve with medication and can lead to corneal perforation. After successful treatment, the center of the cornea may become scarred and cloudy, potentially affecting vision and requiring keratoplasty.

An ophthalmologist.

Eye Health Fungal Infections