Herpetic keratitis is one of the world's leading causes of blindness. The herpes virus causes this eye condition. And those affected may experience several episodes of herpetic keratitis throughout their lives. What is herpetic keratitis? What are the symptoms, and how is it treated? At the end of this article, you'll have the answers to all these questions.
Herpetic keratitis | Definition
Herpetic keratitis is an eye infection caused by the herpes simplex virus, which affects the mouth and eyes. It can infect the cornea, the transparent front part of the eye. Different layers of the cornea can become infected, as can other eye structures, such as the iris.
When it's inactive, the herpes simplex virus remains latent in the human body. The virus is said to be "dormant," meaning that it can reactivate periodically.
Several types of herpetic keratitis are differentiated according to the layer of the cornea they affect.
Here are the three main types of herpetic keratitis:
Epithelial keratitis
It affects the epithelium, the top layer of the cornea. Epithelial keratitis produces linear lesions with branches called dendritic lesions.
As long as the condition remains untreated, these lesions grow and develop. As a result, the longer treatment is delayed, the greater the risk of scarring. And when they are located in the center of the cornea, these scars can lead to vision loss.
Immune stromal keratitis
It occurs after the first episode of epithelial keratitis when the virus is dormant. There is no active virus, but the deepest layers of the cornea are subjected to an inflammatory reaction. This is a reaction of the human body's antibodies. And inflammation of the cornea leads to reduced visual acuity.
Necrotizing stromal keratitis
It occurs when there has already been an episode of epithelial keratitis. Necrotizing stromal keratitis is caused by reactivation and invasion of the virus into the cornea. The virus destroys corneal tissue, triggering an inflammatory reaction.
This is the most severe type of keratitis and is likely to cause visual damage.
What causes herpetic keratitis?
This condition is caused mainly by the herpes simplex virus type 1. It differs from herpes simplex type 2, which affects the genitals. But herpetic keratitis can also be caused by shingles or herpes zoster.
Herpes is a highly contagious disease; once the virus infects a person, it is never eliminated. The virus spreads through mucous secretions and tears. The contagious period can range from a week to several months.
Whenever the virus is activated, there's a risk that a keratitis episode will recur and a risk that the disease will be transmitted.
This is why sufferers must take precautions so as not to affect others. In addition, regular eye exams are necessary for people who have already experienced an episode of herpetic keratitis.
What are the symptoms of herpetic keratitis?
Symptoms differ depending on the type of keratitis a person is suffering from. These may include:
- A sensation of discomfort or a foreign body in the affected eye
- Pain
- Red eyes
- Inflammation of the tissues surrounding the eyes
- Photophobia and glare
- Watery eyes
- Reduced visual acuity
Complications of herpetic keratitis
Reactivation of the herpes simplex virus is frequent, and recurrences of herpetic keratitis can have harmful consequences for the eyes:
- Reduced corneal sensitivity (corneal hypoesthesia)
- Corneal ulceration
- Corneal opacification
- Thinning of the corneal stroma
- Reduced vision
Diagnosis of herpetic keratitis
Diagnosis is made by slit-lamp exam. If there is any doubt about the presence of the virus, the optometrist can refer you to a PCR (polymerase chain reaction) study. PCR will accurately detect the presence or absence of the virus.
What is the treatment for herpetic keratitis?
Treatment always depends on the type of herpetic keratitis and the severity of the condition.
It mainly comprises antiviral tablets, drops and ophthalmic ointments.
For the time being, no treatment can completely eradicate the virus. And should the infection recur and compromise a person's vision, a corneal transplant may need to be considered. The aim is to improve visual acuity.
