Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at December 1, 2016

Keratitis is the inflammation of the cornea. It is usually caused by a bacterial infection but can be caused by other factors as well, including fungal infections, parasitic infections, viral infections, or trauma. An eye doctor should be seen if keratitis is suspected. If left untreated, keratitis can cause further complications to the cornea and ultimately, the patient's vision.


Definition & Facts

The cornea is the dome-shaped window that is found in the front of the eye. The cornea is clear and bends light rays into the eye. The cornea is very thin and provides protection as well as providing focus and vision.

The cornea and sclera make up the outside coat of the eye. Keratitis happens when the cornea becomes inflamed, which can occur from a variety of reasons, including bacteria, parasites, overuse of contacts, injury, or eyelid abnormalities.

Keratitis can become more common with the use of corticosteroids or chemotherapy as they can weaken the immune system's response to bacteria and foreign substances.

Keratitis can range from mild, moderate, or severe. If the inflammation is only on the surface or the epithelial layer of the eye, it is considered superficial keratitis. If the inflammation leads deeper into the layers of the eye, it is called stromal keratitis and is considered to be more serious. The deeper the infection, the higher risk of lasting damage to the eye. Keratitis can be unilateral or bilateral, acute or chronic.

Symptoms & Complaints

Keratitis' most common symptoms are usually eye redness, eye watering, and eye pain. Symptoms of keratitis can include any of the complaints listed below:


Bacteria is usually the most common cause of keratitis. Usually, the surface of the cornea is damaged by a small scratch, opening the layer of the eye to bacterial infections. Bacterial keratitis can also occur from infected or unclean eye makeup. It is important to use eye makeup that is not expired and to regularly clean all makeup brushes.

Viral infections of the cornea can be respiratory tract infections such as the common cold. Fungal infections are the cause of fungal keratitis, which affect patients who are immunocompromised due to another illness or from medications. Contact wearers can suffer from fungal keratitis if their contact cases become dirty or the cases' seal is compromised and begins letting fungi grow.

Wearing contact lenses overnight can also increase the chances of contracting bacterial keratitis. Keratitis can also occur if physical trauma has occurred to the eye. The injury can become infected or remain uninfected and still show the symptoms of keratitis from the trauma.

UV light, tanning lights, over-wearing contact lens, or exposure to chemical agents can cause noninfectious keratitis. If the outer layer of the eye's cells become too dry, they can tear and form surface filaments which can affect the eye and vision. Rarely, disorders of the eyelid or eyelashes can cause the eye to be inflamed. Eyelashes can occasionally grow in the wrong direction, which irritates the cornea causing keratitis.

Diagnosis & Tests

Keratitis is diagnosed by having an eye examination performed by an ophthalmologist. A general eye exam is usually initially performed to determine how well the patient's vision acuity is. Next, a penlight exam will be performed by the ophthalmologist to check the reaction and size of the pupils. At this time, eye drops or an eye stain can be applied to help better see any surface irregularities on the cornea or any corneal ulcers.

They will use a slit lamp to inspect the corneas, which is a microscope that provides illumination and magnification to view the surface of the eye in great detail. If an infection is suspected, a culture can be collected from the surface of the eye to help determine which type of bacteria, virus, or fungi is causing the irritation. 

Treatment & Therapy

Noninfectious keratitis might not require treatment if it is caused by a scratch or extended contact lens wear. The advice may be to simply wear contacts less often until the condition improves.

Infectious keratitis' treatment varies depending on if it is caused by bacteria, fungi, virus, or a parasite. Bacterial keratitis is treated by antibacterial eyedrops. If the infection is severe, oral antibiotics may be required as well.

Fungal keratitis is treated by antifungal eye drops and oral antifungal medication to completely rid the body of the fungi. Antifungal treatment can take months to complete and occasionally is unsuccessful. In severe cases, a corneal transplant may be advised.

Viral keratitis requires antiviral eyedrops, but viral keratitis may reoccur even with treatment. Parasitic keratitis is considered to be the most difficult type to treat. Antibiotics may offer some help, but some of these types of infections are resistant to medication and treatment plans. The parasite can cause permanent damage to the cornea, so a doctor may recommend a corneal transplant.

Prevention & Prophylaxis

People who wear contact lenses should be very careful about keeping their contact lens case clean and to change the solution often. Following one's doctor's instructions for proper contact care and maintenance is important.

If keratitis is reoccurring from overuse of contacts, daily contacts or glasses may be an option to help. Viral keratitis cannot be completely prevented, but the chances of them causing an infection can be decreased. This can include avoiding touching a cold sore of herpes blister to keep the virus from infecting the eyelid or eyes. The best methods to prevent keratitis is to practice proper hygiene, have regular checkups with an eye doctor, and to avoid touching the eyes or the area around the eyes as much as possible.