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Fungal keratitis: Causes, symptoms and treatment

closeup of an eye with fungal keratitis

What is fungal keratitis?

When the cornea (the clear outer surface of the front of the eye) becomes inflamed, this is called keratitis. Fungal keratitis is a subtype of keratitis that is caused by environmental or yeast-like fungi. Fungal keratitis is commonly associated with improper contact lens use.

What causes fungal keratitis?

As the name suggests, fungal keratitis is caused by different fungi. This type of keratitis is somewhat rare, but your eye doctor may still consider it in some cases.

Altogether, there are over 70 types of fungi that can lead to fungal keratitis. However, the majority of cases can often be classified under just three types of fungi: Fusarium, Aspergillus and Candida.

There are many different ways that a person can come into contact with these contaminants, including:

  • Trauma, especially due to vegetation (like being poked in the eye with a stick, thorn or leaf)

  • Improper contact lens usage

  • Contaminated contact lens solution

  • Having a compromised immune system

  • Fungi normally found in the mucous membrane of the eye that has overgrown

Fusarium fungal keratitis

Fusaria are fungi that are generally found in bodies of water, soil and plants. It is an environmental fungus. They used to be more commonly seen in warmer areas, but this association has since been less referenced. Someone could contract fungal keratitis from Fusarium if they experience an eye injury involving a plant contaminant, like being hit in the eye with a tree branch.

Several years ago, there was a breakout of Fusarium fungal keratitis associated with a particular brand of contact solution. It should be noted that most cases of Fusarium fungal keratitis can be traced back to contact lenses and contact lens usage. Fusarium is the most common subtype of fungal keratitis.

LEARN MORE: Fungal eye infections and contact lenses

Aspergillus fungal keratitis

Aspergillus fungi can be found both indoors and outdoors. Like Fusarium, it is an environmental fungus. Aspergillus can be contracted through the spores you breathe in every day. However, most people do not experience any negative side effects from coming into contact with Aspergillus fungi.

Aspergillus fungi most often impact individuals with compromised immune systems or lung diseases.

Candida fungal keratitis

Candida fungi are a yeast-like fungus. Candida usually already exists within a patient’s body and can live on the skin, in the throat or mouth, or even in the gut without causing any issues. As it relates specifically to fungal keratitis, Candida fungi usually reside on the mucosal membrane of the eyes.

Candida fungal keratitis is the only fungal keratitis subtype of the main three that is not caused by external sources. Instead, it is caused by the fungi that are already present in the patient’s body.

What are the signs and symptoms of fungal keratitis?

The symptoms of fungal keratitis share a lot of similarities and overlap with typical keratitis symptoms, including:

You may experience just a couple or several of these symptoms at any time. If you experience any of these symptoms, you should contact an eye doctor as soon as possible to schedule an eye exam. 

During your appointment, your eye doctor will go over your medical history and ask about your symptoms. They may also collect some tears or a tiny sample of corneal tissue to verify your diagnosis and provide the best treatment.

How is fungal keratitis treated?

While some types of keratitis can often be mild and not cause many long-term complications, fungal keratitis can be severe and destructive if not diagnosed and treated early.

To diagnose your infection, an eye doctor may take a tissue sample from your eye. This tissue sample will be tested to determine if an abnormality is present. Once a diagnosis has been determined, your eye doctor will recommend a course of treatment.

Fungal keratitis can be treated with antifungal eye drops or prescription medications taken by mouth. If these methods prove to be ineffective, a more invasive approach may be needed. Surgery (such as a corneal transplant) could be recommended if the remaining tissue is progressively worsening or failing to recover.

Patients with fungal keratitis may run the risk of experiencing impaired vision or vision loss if their condition is not diagnosed early. In cases like these, even a surgical solution may not fully restore a person’s sight. This is why it’s important to act quickly if you notice any symptoms or problems with your eyes. An early diagnosis improves the chances of a smoother recovery.

When should I see an eye doctor?

Keeping your eyes healthy is vitally important. You should contact an eye doctor if you begin to notice any symptoms of eye discomfort or decreased vision. They can assess your symptoms and determine an accurate diagnosis and appropriate course of treatment. 

READ NEXT: What is punctate keratitis? and Neurotrophic keratitis

Basics of fungal keratitis. Centers for Disease Control and Prevention. February 2022.

What is fungal keratitis? American Academy of Ophthalmology. January 2022.

Fungal keratitis. EyeWiki. January 2022.

Fungal keratitis. Medscape. July 2019.

Fungal keratitis. Columbia Eye. Accessed May 2022.

Fusarium keratitis in Germany. Journal of Clinical Microbiology. September 2017.

Aspergillosis. Center for Disease Control and Prevention. May 2021.

Candidiasis. Center for Disease Control and Prevention. October 2020.

Keratitis. Prevent Blindness. Accessed May 2022.

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