What is Herpes Keratitis?

It is a disease caused by the infection herpes simplex virus (HSV) in the eye. It can compromise the deeper layers of the cornea, causing scarring of the cornea, loss of vision, and even blindness. Herpes keratitis can also be caused by the herpes zoster virus, known as "shingles." Symptoms, conditions, and treatment are different from herpes simplex keratitis.


How is Herpes Keratitis Spread?


The herpes simplex virus is spread by mucosa to mucosa contact or by secretions produced by infected mucous membranes, such as from mouth to mouth or from virus-laden saliva or tear to the eye. Once the virus infects the eye, it is never eliminated. When the symptoms disappear, the virus becomes latent in the nervous system of the eye. When the virus is activated is when the keratitis recurs. There are several hypotheses about the factors that can "wake up" the sleeping virus and cause recurrent keratitis. Exposure to the sun, stress, or low defenses, are some of them, although studies to date have not been confirmed.


Symptoms

Close Up of Conjunctivitis During Eye Examination
Herpes Keratitis Conjunctivitis


The symptoms of the first eye infection by the herpes simplex virus are produced by conjunctivitis. When the virus first infects the cornea, it usually affects the epithelium, the outermost layer. Pain, red-eye, discomfort due to light, tearing, and blurred vision are the most frequent manifestations.


When the virus is reactivated, it can re-infect the epithelium or the deeper layers of the cornea, such as the stroma, the thickest layer of the cornea, or the endothelium, the most posterior layer. Furthermore, it can cause an inflammatory reaction in the corneal stroma or within the eye itself. The main symptoms of this affection are loss of vision, pain, red-eye, and discomfort due to light.


Types of Herpes Keratitis


The types of herpetic keratitis depend on the layer of the cornea that is affected and whether the keratitis is caused mainly by direct infection of the virus or by the inflammatory reaction caused by the virus:


1. Epithelial Keratitis: The virus invades the corneal epithelium producing linear branching lesions called dendritic lesions. If left untreated, these lesions widen and grow, giving the appearance of maps called geographic lesions. The longer it takes to treat and heal, the more scar it can leave, causing permanent vision loss, especially if the center of the cornea is affected.


2. Immune Stromal Keratitis: It appears when there has already been an episode of epithelial keratitis, and the virus has been latent. This type of keratitis is due to inflammation by virus particles within the stromal layer of the cornea. There is no active virus. The cornea becomes swollen, causing loss of vision. The corneal epithelium is intact.


3. Necrotizing Stromal Keratitis: This type of keratitis affects the corneal stroma, but contrary to the previous type, necrotizing stromal keratitis is produced by reactivation and a direct invasion of the virus into the cornea. Also, it tends to cause more virulent corneal inflammation, and symptoms are more severe. The cornea becomes swollen, but there is also an invasion of white blood cells in this area, giving a similar appearance to a corneal infection by other germs such as bacteria or fungi. It is very important to rule out these causes of infection by lab analysis of the affected zone.


4. Endotheliitis: It is a direct virus infection with secondary inflammation in the deepest layer of the cornea, the endothelium. Also, it causes an inflammatory reaction within the eye. The cornea becomes swollen, and there are white blood cell cells attached to the endothelium and floating within the aqueous humor, the fluid that is inside the eye.


Treatment

Woman Treating Herpes Keratitis With Eye Drops
Treating Herpes Keratitis


Treatment of the infection should be individualized by your ophthalmologist, depending on the severity of the condition. Generally, mild infections are usually treated with ophthalmic ointments, occasionally combining oral antiviral medication. In severe cases with corneal scars that cause decreased visual acuity and astigmatism that cannot be corrected with glasses or contact lenses, a corneal transplant may be necessary. The prognosis of this surgery is better if the inflammation has been inactive for at least six months before the surgery. It is very important to always consult an ophthalmologist before starting any treatment as some medications or drops can make the infection worse.


How to Prevent It?


For the prevention of contagion and recurrence of this virus in the eye, it is important to avoid touching the eyes if we have an active outbreak in another location in the body. Also, avoid using corticosteroid eye drops without consulting an ophthalmologist, as these can cause the virus to multiply. Do not wear contact lenses if there are recurrences or if you are having an acute episode.


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