- What are herpes viruses?
- What causes herpes eye infections?
- Is ocular herpes contagious?
- How do people transmit ocular herpes?
- What parts of the eyes are susceptible to herpes viruses?
- Who is at risk for herpes infections of the eyes?
- What is the incubation period for ocular herpes?
- What are the signs and symptoms of herpes eye infections?
- What health care professionals diagnose and treat ocular herpes?
- How do health care professionals diagnose herpes eye infections?
- What are treatment options for herpes eye infections?
- What are the possible risks and complications of untreated herpes eye infections?
- What is the prognosis of herpes eye infections?
- Is it possible to prevent herpes eye infections?
What are herpes viruses?
There are several members of the herpes virus family. They include herpes simplex virus-1 (HSV-1) and herpes simplex virus-2 (HSV-2), herpes zoster (HZV, also known as varicella-zoster virus or VZV), cytomegalovirus (CMV), and others.
What causes herpes eye infections?
The two types of herpes virus that most commonly affect the eyes are herpes simplex virus-1 (HSV-1) (the same virus that causes cold sores on the lips) and varicella-zoster virus (VZV; herpes zoster), which causes chickenpox in childhood and shingles in adulthood.
Is ocular herpes contagious?
Herpes can be contagious. People with active corneal herpes simplex and herpes zoster have live virus in their tears, as well as skin vesicles in chickenpox and shingles rashes. Careful hand washing is important, particularly when in contact with unimmunized babies and children, as well as people with weakened immune systems.
How do people transmit ocular herpes?
In most cases, people do not transmit ocular herpes simplex from one eye to another. Instead, people first acquire the virus by direct contact but typically produces no initial signs or symptoms other than a mild rash or pink eye that subsides on its own. The virus settles in the body's nervous system, where it remains in its latent, dormant state. Months or years later, the virus can reactivate and travel to the eye where it causes ocular herpes, or the lip, where it causes a cold sore.
Individuals most often acquire herpes zoster (varicella zoster) virus through the air during epidemics of chickenpox in childhood, after which the virus can sit dormant for decades before reactivating and producing shingles in the eye or elsewhere in the body.
What parts of the eyes are susceptible to herpes viruses?
All the parts of the eye are susceptible. Herpes ophthalmicus is the term for herpes infection of any part of the eye.
HSV and HZV most often affects the cornea. Herpetic keratitis is infection or inflammation of the cornea. But these viruses can also affect the skin of the eyelids, the uveal tissue (iris and choroid), and the retina. For this reason, physicians recommend a thorough eye exam to assess the extent of eye involvement.
Who is at risk for herpes infections of the eyes?
Although a very large percentage of the population (85% or more) carries the HSV-1 virus, not everyone who carries the virus gets an eye infection.
When a person carrying the virus becomes immunocompromised (for example their immune system becomes weakened) due to HIV, medications (steroids, chemotherapy), age, and perhaps stress, the virus is more likely to become "active" and incite an outbreak that may include an eye infection.
However, in many (if not most) cases of HSV keratitis, the frequency of eye infections appears to be random and not necessarily associated with episodes of stress or immune weakness. In fact, studies have suggested that the particular subtype of HSV-1 virus that an individual acquires has as much to do with the frequency of eye infections as the individual's immune system.
What is the incubation period for ocular herpes?
The incubation period (the time between acquiring the virus and the appearance of ocular symptoms) can range from a few days to several decades.
What are the signs and symptoms of herpes eye infections?
The most common presentation for ocular HSV and HZV infection is pain, blurred vision, redness, tearing, and light sensitivity in one eye.
What health care professionals diagnose and treat ocular herpes?
Your primary care doctor (family practice doctor, pediatrician, or internist) often makes an initial diagnosis, but in most cases, individuals should follow up with an eye doctor (optometrist or ophthalmologist). Special eye examination equipment allows a much more detailed assessment, and physicians can tailor the treatment plan to the degree and extent of eye involvement.
How do health care professionals diagnose herpes eye infections?
Most of the time, physicians make the diagnosis based on the symptoms and the signs alone.
Herpes keratitis typically produces a distinct erosion of the outer layer of the cornea (a "dendrite"), which has a tree-branching pattern that can be seen by the examiner using a blue light and an eyedrop containing a dye. Under a slit-lamp microscope, the eye doctor can look for further clues to distinguish between a HSV and a HZV keratitis, but in either case, the initial antiviral treatment is the same.
Health care professionals perform a close examination of the other eye tissues (including the skin, conjunctiva, anterior chamber, iris, retina, and more) to assess the extent of the infection. In questionable cases, doctors obtain a culture to confirm the diagnosis.
What are treatment options for herpes eye infections?
Initial treatment is with either topical (drop) or oral antiviral medication. In certain less common cases, intravenous medication is also necessary.
The antiviral drugs currently available work by suppressing the reproduction of the virus, thus reducing the number of active viruses. This may shorten the duration and severity of the infection and possibly reduce the odds of a recurrence.
Unfortunately, there is still no antiviral medication that "cures" one of herpes. The herpes viruses reside in the cells in our nervous system where they remain inactive and quiet ("latent") for months or years. No treatment has been developed to date that can eradicate the viruses in their latent state.
When the virus becomes "active" for whatever reason, it begins reproducing and its progeny virus travel along a nerve to the site of the infection (at the skin or cornea). The antiviral medications available today only affect these actively replicating viruses, not the latent viruses in the nervous system.
In addition to antiviral medications, patients may use antibiotic drops or ointment as a preventative measure to reduce their chances of a bacterial infection developing in the area of viral infection. This is because an eroded cornea becomes more vulnerable to a secondary bacterial infection.
The eye pressure (intraocular pressure) can rise due to internal swelling (inflammation) of the eye or direct herpes virus infection of the trabecular meshwork (the internal drainage channels within the eye). If so, doctors will prescribe a pressure-lowering medication.
Herpes affecting the middle layer of the cornea (herpetic stromal keratitis), back layer of the cornea (herpetic endotheliitis), and iris (herpetic iritis) are associated with significant inflammation. Inflammation of any of the tissues of the eye may require anti-inflammatory medications such as steroids. In some cases, the inflammation is chronic or recurring, requiring several rounds of steroid treatment.
What are the possible risks and complications of untreated herpes eye infections?
In the worst-case scenario, untreated herpes eye infections lead to blindness, chronic pain, and loss of the eye. Aggressive treatment aims to reduce the chances of scarring, eye pressure problems, and direct damage to the eye tissues.
What is the prognosis of herpes eye infections?
Most herpes simplex keratitis (HSV eye infections) are limited to the outer layer of the cornea and resolve within a couple of weeks with antiviral therapy, leaving little or no permanent damage. HSV infections of the deeper tissue layers may have a higher complication rate due to inflammation.
HZV and shingles involving the outer layer of the cornea may also resolve over a couple of weeks with antiviral therapy. However, it is common for a painful burning sensation to linger in the area of the skin rash for months or even years. This is postherpetic neuralgia and sometimes requires treatments for pain control. Both types of herpes eye infections can leave residual corneal scarring that can blur the vision. In some cases, it's possible to correct this with surgery.
Damage to the corneal nerves can also lead to chronic numbness of the cornea, causing dry eye and, in advanced cases, predisposing to dry-eye related corneal erosions or ulcers. In these cases lubricating drops, punctal plugs, and sometimes eyelid surgery may help protect the cornea.
Unfortunately, both HSV and HZV ophthalmicus can recur with unpredictable frequency in either eye. Frequent recurrences should warrant a general medical checkup to rule out any underlying condition that may be weakening the immune system. However, in many cases, it is the virulence of the particular virus strain that determines its activity level.
Is it possible to prevent herpes eye infections?
For patients with frequent recurrences of herpes eye infections, taking a low-dose antiviral drug on a daily basis can reduce the frequency of recurrences in some cases. Your eye doctor will help determine if this is a safe option.
There is no vaccine against HSV at this time. There is a vaccine against chickenpox for babies and toddlers (varicella vaccine). A zoster vaccine (approved for adults 50 years of age and over) may reduce the frequency and severity of shingles and HZV eye disease. The U.S. Centers for Disease Control and Prevention (CDC) recommends that all adults aged 60 and over receive this vaccine but does not recommend vaccination of those aged 50-59. Research is ongoing to develop a means of eradicating the viruses in their latent states.
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Farooq, A. V., et al. "Herpes simplex epithelial and stromal keratitis: an epidemiologic update." Survey of Ophthalmology 57.5 (2012): 448-462.
Potts, A., G.J. Williams, J.A. Olson, K.G.J. Pollock, H. Murdoch, and J.C. Cameron. "Herpes zoster ophthalmicus reduction: implementation of shingles vaccination in the UK." Eye (Lond) 28.3 Mar. 2014: 247-248.