Eye pain, tearing, redness, a feeling like a foreign object is in the eye (foreign body sensation), and sensitivity to bright light are common symptoms.
Doctors diagnose herpes simplex keratitis based on an examination of the person's cornea and sometimes by swabbing the eye to identify the virus.
Treatment is with antiviral drugs.
(See also Introduction to Corneal Disorders Introduction to Corneal Disorders The cornea is the clear layer in front of the iris and pupil. It protects the iris and lens and helps focus light on the retina. It is composed of cells, protein, and fluid. The cornea looks... read more .)
An Inside Look at the Eye
 |
The herpes simplex virus Herpes Simplex Virus (HSV) Infections Herpes simplex virus infection causes recurring episodes of small, painful, fluid-filled blisters on the skin, mouth, lips (cold sores), eyes, or genitals. This very contagious viral infection... read more 
(which causes cold sores) never leaves the body after an initial (primary) infection. Instead, the virus remains in a dormant (inactive) stage in the nerves. Sometimes, the virus reactivates and causes a recurrence and further symptoms.
Primary herpes simplex eye infections usually occur in children and cause a mild keratoconjunctivitis, which is inflammation of the cornea and of the conjunctiva (the membrane that lines the eyelids and covers the white of the eye).
The primary infection resolves without treatment. However, if the infection reactivates, it can affect the cornea more seriously and may result in temporary or permanent visual loss.
Herpes simplex keratitis is a major cause of blindness worldwide.
Symptoms of Herpes Simplex Keratitis
Symptoms of primary (first) herpes simplex eye infections usually resemble those of common conjunctivitis, so the diagnosis of herpes simplex infection is not made.
Symptoms of a reactivation include tearing, redness, a feeling like a foreign object is in the eye (foreign body sensation), and sensitivity to bright light. Rarely, the infection worsens and the cornea swells, making vision hazy. The more often the infection recurs, the more likely is further damage to the surface of the cornea. Several recurrences may result in the formation of deep ulcers, permanent scarring, blood vessels that grow onto the cornea, and numbness of the eye surface.
With multiple recurrences, the herpes simplex virus can lead to significant visual impairment, which can be permanent.
Diagnosis of Herpes Simplex Keratitis
An eye examination
Sometimes a culture or other laboratory test
To diagnose a herpes simplex infection, a doctor examines the eye with a slit lamp What Is a Slit Lamp? 
(an instrument that enables doctors to examine the eye under high magnification). During the examination, the doctor may put drops in the eyes that contain a yellow-green dye called fluorescein. The fluorescein dye temporarily stains the damage in the cornea a bright green, making it possible for the doctor to see a damaged area that is not otherwise visible.
Sometimes, the doctor may swab the infected area to identify the virus (viral culture).
Treatment of Herpes Simplex Keratitis
Antiviral eye drops
Antiviral drugs taken by mouth or vein
Corticosteroid eye drops and drops that dilate the pupil
Sometimes removal of infected and damaged eye cells
Treatment of herpes simplex keratitis should be started as soon as possible.
The doctor may prescribe an antiviral drug, such as trifluridine eye drop or ganciclovir eye gel.
Acyclovir, another antiviral drug, can be taken by mouth or by vein (intravenously). The antiviral drug valacyclovir can also be taken by mouth.
Deep infections that cause a lot of inflammation may require use of corticosteroid drops and drops that dilate the pupil, such as cyclopentolate, atropine or scopolamine.
Occasionally, to help speed healing, an ophthalmologist (a medical doctor who specializes in the evaluation and treatment—surgical and nonsurgical—of eye disorders) gently swabs the cornea with a soft cotton-tipped applicator to remove infected and damaged cells.
