Herpes Simplex Virus vs. Herpes Zoster Virus: What's the Difference?

Herpes simplex virus (HSV) and herpes zoster virus (VZV) are two types of viruses that can cause infections in the eye. HSV is the most common cause of corneal infections, while VZV is the cause of shingles.

Herpes Simplex Virus

HSV is a double-stranded DNA virus that can infect the skin, mouth (“cold sores”), eyes (“dendritic ulcers”), and genitals. There are two subtypes HSV-1 and HSV-2.  HSV-1 is usually the infectious agent in ocular infections, HSV-2 is usually the cause of genital infections. 

It is spread through contact with the virus-containing fluid from an open sore. Once a person is infected with HSV, the virus remains dormant in the body for the rest of their life. It can reactivate and cause an infection at any time. 

HSV keratitis is one of the most common causes of corneal blindness in the developed world.  Antiviral medications, such as topical or oral antiviral drugs, are commonly prescribed to manage HSV eye infections and reduce the risk of complications.

A typical dendritic ulcer caused by HSV-1.

Herpes Zoster Virus (also called Varicella Zoster Virus)

VZV is also a double-stranded DNA virus. It is the same virus that causes chickenpox. After a person recovers from chickenpox, the virus remains dormant in the body for the rest of their life. It can reactivate and cause shingles, which is a painful rash that can occur anywhere on the body, including the face and eyes.

When Shingles involves the ophthalmic branch of the trigeminal nerve (V1) or less commonly the maxillary branch (V2) the eye can be involved.  A positive Hutchinson’s signs (lesions involving the tip of the nose) is strongly predictive of ocular involvement. 

Treatment

Both HSV and VZV keratitis are treated with antiviral medications.  The use of steroids is nuanced in HSV keratitis but is vital in VZV keratitis.  Treatment of corneal scarring depends on the depth of the scarring.  Superficial keratectomy, phototherapeutic keratectomy (“PTK”), topography guided PTK (“t-PTK”) and corneal transplantation are some of the treatments that may be required for visual rehabilitation.  Treatment options are much more limited in patients with a neurotrophic cornea due to limited healing. 

If you think you may have an ocular herpes virus infection, see your optometrist immediately. Early treatment can help to prevent serious complications.