Keratitis - Causes, Symptoms and Treatment

Keratitis, infection of the cornea, may occur as a result of bacterial, fungal or viral invasion. Infection of the cornea is a sight threatening process.

Causes of Keratitis

The most common cause of keratitis is infection by herpes simplex virus, Type 1 (known as dendritic because of the characteristic branching lesion that occurs). Bacterial corneal ulcers frequently occur as a result of an infected corneal abrasion or contaminated contact lens. Fungal keratitis is more frequently encountered in tropical climates. Poor lid closure can result in exposure keratitis. Chemicals splashed in the eye can also produce keratitis.

Signs and Symptoms of Keratitis

Usually unilateral, a patient presents with decreased vision, discomfort ranging from mild irritation to acute pain, tearing, and photophobia. When keratitis results from exposure, it usually affects the lower portion of the cornea. Visual acuity may be decreased if the lesion is central. On gross examination with a pen light, the corneal light reflex might be distorted.

Diagnosis for Keratitis

A slit-lamp examination confirms keratitis. Staining the eye with a sterile fluorescein strip enables the examiner to discern the extent and depth of the corneal lesion. Patient history may reveal a recent infection of cold sores, or eye irritation while wearing contact lenses.

Treatment for Keratitis

In acute keratitis due to herpes simplex virus (HSV), treatment consists of trifluridine eye drops or vidarabine ointment. A broad-spectrum antibiotic may prevent secondary bacterial infection. HSV keratitis is treated in a doctor's office. Dendritic keratitis may become chronic, with recurrent episodes. Long-term topical therapy may be necessary. (Corticosteroid therapy is contraindicated in dendritic keratitis or any other viral or fungal disease of the cornea.)

Bacterial corneal ulcers require intense topical eye drop instillation every 1/2 hour for the first 48 hours with two broad-spectrum antibiotics. Treatment for fungal keratitis consists of natamycin. Bacterial and fungal corneal ulcers are treated in hospital.

Exposure keratitis is treated with application of ointment at night and frequent instillation of artificial tears during daytime. A plastic bubble shield may prevent tear evaporation. Vision may be restored by penetrating keratoplasty (comeal transplant) when blindness results from corneal scarring.

Special Considerations and Prevention Tips for Keratitis

• Be aware that the patient with a red eye may have keratitis. Check for a history of contact lens wear, cold sores, or recent foreign body sensation. Refer patient for slit-lamp examination as soon as possible for treatment.
• Protect the exposed corneas of unconscious patients by cleaning the eyes daily, applying moisturizing ointment, or covering the eyes with an eye shield.