Herpetic keratitis is an infection of the cornea, the transparent front part of the eye, caused by the herpes simplex virus. While the herpes simplex virus that affects the genitals is type 2, the type that affects the eys and mouth is type 1.
This infection may affect the different layers of the cornea and cause an inflammatory reaction. It may also affect the most profound structures of the eye like the iris and cause inflammation inside the eye.
The cause of herpetic queratitis may also be the herpes zoster virus, commonly known as "shingles". The symptoms, affectations and treatment are different to herpetic simplex keratitis.
The symptoms of an initial eye infection caused by the herpes simplex virus are caused by conjunctivitis which may pass for conjunctivitis caused by any other virus. Red eye, watering eyes, discomfort and stinging are the main symptoms.
When the virus infects the cornea for the first time, it generally affects the epithelium, the most external layer. Pain, red eye, discomfort caused by light, watering eyes and blurred vision are the most common manifestations.
When the virus reactivates, it can once again infect the epithelium or the most profound layers of the cornea like the stroma, the thickest layer of the cornea, or the endothelium, the inner most layer of the cornea, In addition, it may cause an inflammatory reaction in the corneal stroma or inside the eye itself. The main symptoms of this affectation are a loss of vision, pain, red eye and discomfort caused by light.
The herpes simplex virus is transmitted through mucosa to mucosa contact or by secretions from infected mucosas, like mouth to mouth or saliva or tears containing the virus coming into contact with to the eye. Once the virus infects the eye, it can never be eliminated. When the manifestations or symptoms of keratitis disappear, the virus remains dormant in the nervous system of the eye.
When the virus activates, the keratitis recurs. There are different hypotheses on the factors that may "awaken" the dormant virus and cause recurrent keratitis. Exposure to the sun, stress or a low immunity system are just a few of these, although studies have not been able to confirm this.
The types of herpetic keratitis depend on the layer of the cornea affected and if the keratitis is caused mainly by a direct infection of the virus or by an inflammatory reaction caused by the virus.
Prevention is not touching your eyes with hands that may be infected by secretions containing the virus. Do not use eyedrops, tissues or towels of patients with keratitis in whom the disease is active.
Treatment involves a topic antiviral medication for keratitis caused by the active virus.
If the main cause of the keratitis is inflammation, a topic corticosteriod should be used as directed by your ophthalmologist and always along with adjuvant antiviral treatment as the use of a corticosteroid without preventive antiviral medication may reactivate the virus and cause another type of keratitis. In some cases, the use of systemic antiviral or corticosteroid treatment is indicated.
In cases where herpetic keratitis has caused corneal cicatrisation that compromises the eyesight, a cornea transplant is the most suitable option for restoring vision.
Frequently asked questions
There is no measuring stick nor factor that can predict if the herpes simplex infection will recurr or not. A patient who knows that they have the virus must be alert in case the eye begins to show symptoms like red eye, discomfort, a gritty sensation or blurred vision. If this is the case, they should go to the ophthalmologist immediately to get a diagnosis and receive treatment as soon as possible so that the infection and inflammation leave as little corneal cicatrisation as possible.
The herpes simplex virus stays in the nervous plexus of the eye and even the nerves outside the cornea. Changing the cornea does not mean that the virus has been eradicated. Keratitis may come back in the newly transplanted cornea.