Fungal keratitis

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at December 29, 2016
StartDiseasesFungal keratitis

Although fungal eye infections are not common, they can be very dangerous. Fungal keratitis, which can develop after an eye injury, is more common in developing countries than developed ones. It requires prompt diagnosis and treatment to prevent serious damage, including blindness.

Contents

Definition & Facts

Different types of fungi can infect the cornea, which is the clear round dome that covers the pupil and iris in the eye. The infection that they cause is known as fungal keratitis. The term keratitis generally refers to an inflammation of the cornea, and fungal keratitis is the type of inflammation that results from a fungal infection.

The condition is more common in tropical climates. However, there are increasing incidences of the disease in developed countries where the main causes are contact lenses.

Symptoms & Complaints

The condition manifests symptoms that are largely similar to those of other corneal infections. Some of the common signs include:

The pain does not usually subside even with the removal of contact lenses or treatment with antibiotics. The eyelids tend to show edema (swelling caused by the collection of excess watery fluid). An ulcer may also be present.

While it is important to diagnose the disease in its early stages, this is often a challenge. Establishing the clinical diagnosis may prove tricky, especially considering that the symptoms are similar to those of other corneal problems.

Causes

Fungal keratitis typically results from ocular trauma, that is, an injury to the eyes. Fungi can infect the cornea after an injury, penetrating deeply into the corneal tissue. Some of the fungi that are responsible for the disease are Fusarium, Aspergillus, and Candida. The first two genera are normally found in the environment while the third genus usually live on human skin. Fungal infections of the cornea are not transmitted from one person to another.

Risk factors include participating in agricultural activities and living in a hot climate. However, the disease is becoming more common in temperate regions. A common cause is the use of contact lenses. Other conditions that put people at risk of infection include a weakened immune system and underlying eye disease.

Ulcers may also contribute to the likelihood of the disease. Another cause is the increasing use of antibiotics and topical corticosteroids. Medical procedures that affect the corneal nerves can also lead to a fungal infection.

Diagnosis & Tests

Clinical specialists emphasize the importance of making a definitive diagnosis before starting any treatment regimen. Such a diagnosis involves asking about a patient's symptoms, taking a patient’s medical history, performing an eye examination, and doing laboratory tests.

The doctor will inquire about the patient's recent travel history. If they traveled to a tropical climate, this may arouse suspicion. The physician will also ask about the patient's use or misuse of contact lenses as well as if they have any condition that may weaken their immune system.

However, no conclusive diagnosis can be reached without clinical tests. Gram stains are useful in cases where the physician is not sure of the microbe involved. Other useful stain tests for identifying different pathogens include calcofluor-white, Grocott's methenamine silver stain, and Giemsa staining.

Cultures are also useful in determining the presence of fungal keratitis. This involves scraping a specimen of tissue for a culture test. This can be relatively easy where fungi are involved. It may also be necessary to perform a biopsy

Treatment & Therapy

The first line of treatment involves the use of oral and topical antifungal treatments. Patients who do not respond to these treatments may undergo surgery.

Econazole eye drops may be administered hourly for the initial 24 to 48 hours. For patients suffering from ocular surface disease, the ophthalmologist may prescribe amphotericin B eye drops. Voriconazole eye drops have also proven to be successful in the treatment of fungal keratitis.

A senior ophthalmologist may recommend the use of topical steroids, which are normally started 48 hours after taking topical antifungal treatment. When various medical treatments fail, surgical intervention may be necessary, including corneal transplant.

Prevention & Prophylaxis

Useful preventive measures include:

  • Wearing safety glasses and other protective eyewear while doing work that exposes the eyes to possible injury
  • Proper contact lens care
  • Avoiding nonessential steroid use