金台診所醫學美容的部落格

By Prof.Dr.Gehad Elnahri
Herpetic Eye disease


Herpes simplex virus is one of the most common viruses to infect the eye. Most people are infected by type I virus early in life so that more than 90% have antibodies against the virus.

The first infection of the eye may occur during the primary viremia usually in childhood and is commonly a blepharoconjunctivitis and NOT a keratitis, that is usually not distinguishable from other childhood infections and passes unnoticed in a week except in children suffering from generalized atopy where the virus may assume more severe forms

1.Primary herpetic infection; mucopurulent blepharoconjunctivitis with or without fine vesicles on the lid
The virus then resides in the Vth nerve ganglion and recurrently descends in its branches in some people, for some unclear reasons but the pattern is constant for the same person
It may descend with fever in some, with menses in some, in Spring, with stress etc
Descent along the mandibular branch is rare, along the maxillary branch V2 is common (herpes at the corner of mouth, lip, or side of nose seen frequently with fever)
The cornea is affected when the virus descends along V1 (ophthalmic branch) causing corneal herpetic ulcer.

2.Postprimary (recurrent) infection; corneal herpetic (dendritic) keratitis
Dendritic ulcer is one of the most common corneal ulcers. It is most common between puberty and 30 years where it is the most common infective corneal ulcer at this age, so always consider herpes at that age.
Some people get one attack, others have regularly recurring disease. Some have mild self-limited disease, others have a devastating course.
The ulcer is typically superficial, with few symptoms due to viral anesthesia of corneal nerves and is quite difficult to diagnose without slit lamp examination unless one keeps a high index of suspicion. It is usually self-limited and cures in 1 week like blisters at the angle of the mouth and pass unnoticed. Unfortunately many cases that persist are iatrogenic in origin because of the habit of prescribing steroids/antibiotics for anyone with ocular irritation. Steroids are the kiss of life for the virus. It stays and complicates.

RULE 1: never prescribe steroids for age 15-35 with unilateral eye irritation except after careful slit lamp examination.
At this point i would like to mention an important dd; recurrent corneal erosion. This condition is sometimes very difficult to differentiate from recurrent herpetic ulcer except by careful history taking and some subtle clinical signs that are missed even by experts.
The treatment of herpetic or dendritic corneal ulcer is topical antivirals. In Egypt unfortunately we had several topical antivirals that disappeared one by one and this is a nice story.
Topical antivirals are either Non specific; act on DNA of viral cells and human cells, so kill the virus but are toxic to corneal epithelial cells like idoxuridine or trifluridine (Bephen) 
Or Specific acting only on viral DNA like acyclovir and valacyclovir and less toxic to epithelial cells.
When acyclovir appeared and with the wide-spread publicity of non-toxicity, the use of other anti-virals decreased to the point that they were no longer profitable and were withdrawn from the market. This is a Common Mistake of medical teaching and is seen most clearly in Antibiotic treatment, where an introduction of a new antibiotic class like fluoroquinolones is associated with a surge of non-indicated use until they become rapidly ineffective due to bacterial resistance.

RULE 2: REFRAIN from prescribing strong new antibiotic classes for simple conditions curable by other antibiotics.
Anyway, all antivirals disappeared except acyclovir (Zovirax) which was a mistake because Specificity is linked with Resistance to drug because when the drug acts on one point this is an invitation to the virus to modify this point.

RULE 3: dendritic ulcer should cure in 1 week, if not consider other causes/complications
The post is getting long so we will discuss Complicated Herpetic ulcers in a second post.