Disease: Herpes Viruses of the Eyes

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.

Which types of herpes viruses can affect the eyes?

Herpes simplex virus-1 (HSV-1) is the most common herpes virus to affect the eyes. This is the same virus that causes cold sores on the lips. Herpes zoster which causes chickenpox in childhood and shingles in adulthood, can also affect the eye. Cytomegalovirus causes eye disease in immunocompromised people, such as HIV-infected patients with low T cell counts.

What parts of the eyes are susceptible to herpes viruses?

All the parts of the eye are susceptible to infection. When any part of the eye is affected, it is referred to as herpes ophthalmicus.

The cornea is most often affected by HSV and HZV. Infection or inflammation of the cornea is known as keratitis. But these viruses can also affect the skin of the eyelids, the uveal tissue (iris and choroid), and the retina. For this reason, a thorough eye exam is recommended 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 eye infection.

However in many (if not most) cases of HSV infection, 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 that an individual harbors has as much to do with the frequency of eye infections as the individual's immune status.

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. HZV is also often accompanied by a shingles rash (small "vesicles," or blisters) on the forehead on the side that is affected and sometimes the tip of the nose.

How are herpes eye infections diagnosed?

Most of the time the diagnosis can be made based on the symptoms and the signs alone.

Herpes keratitis typically produces a distinct erosion of the outer layer of the cornea. This tiny erosion is called a "dendrite" and has a tree-branching pattern that can be seen by the examiner using an eye drop with a yellow dye and a blue light. Under a slit-lamp microscope the eye doctor can look for further clues to distinguish between an HSV and an HZV keratitis, but in either case, the initial antiviral treatment is the same.

Close examination of the other eye tissues (including the skin, conjunctiva, anterior chamber, iris, retina, and more) also offers additional clues to make the diagnosis as well as helps tailor treatment. In questionable cases, a culture can be obtained to confirm the diagnosis.

How are herpes eye infections treated?

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 suppress 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. When we acquire herpes viruses, they incorporate themselves into 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 when in their latent state.

When the virus becomes "active" for whatever reason, it begins reproducing and its progeny viruses 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, antibiotic drops or ointment might be used preventatively to reduce chances of a bacterial infection developing in the area of viral infection. This is because when the cornea is eroded, it becomes more vulnerable to a bacterial infection.

If the eye pressure (intraocular pressure) rises due to internal swelling (inflammation) of the eye or direct herpes virus infection of the trabecular meshwork (the internal drainage channels within the eye), a pressure-lowering medication will also be necessary.

Inflammation of any of the tissues of the eye may be so significant as to require anti-inflammatory medications such as steroids. While steroids can control inflammation very well, they can also compromise the immune system, so most often they are carefully introduced once the active viruses are well controlled by antiviral medication. 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 is aimed at reducing the chances of scarring, eye pressure problems, and direct damage to the eye tissues.

What is the prognosis of herpes eye infections?

Thankfully, the majority of HSV eye infections is limited to the cornea and resolve within a couple of weeks with antiviral therapy, leaving little or no permanent damage.

With HZV and shingles, the keratitis may resolve over a similar time frame. However, it is not uncommon for a painful burning sensation to linger in the area of the skin rash for months or even years. This is referred to as "post herpetic neuralgia" and sometimes responds to neurologic medications aimed at suppressing the pain nerves.

Both types of herpes eye infections can leave a residual corneal scar that can blur the vision. In some cases, this can be corrected with surgery. Damage to the corneal nerves can also lead to chronic, mild-to-moderate 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.

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 eye infection.

However in many (if not most) cases of HSV infection, 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 that an individual harbors has as much to do with the frequency of eye infections as the individual's immune status.

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. HZV is also often accompanied by a shingles rash (small "vesicles," or blisters) on the forehead on the side that is affected and sometimes the tip of the nose.

How are herpes eye infections diagnosed?

Most of the time the diagnosis can be made based on the symptoms and the signs alone.

Herpes keratitis typically produces a distinct erosion of the outer layer of the cornea. This tiny erosion is called a "dendrite" and has a tree-branching pattern that can be seen by the examiner using an eye drop with a yellow dye and a blue light. Under a slit-lamp microscope the eye doctor can look for further clues to distinguish between an HSV and an HZV keratitis, but in either case, the initial antiviral treatment is the same.

Close examination of the other eye tissues (including the skin, conjunctiva, anterior chamber, iris, retina, and more) also offers additional clues to make the diagnosis as well as helps tailor treatment. In questionable cases, a culture can be obtained to confirm the diagnosis.

How are herpes eye infections treated?

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 suppress 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. When we acquire herpes viruses, they incorporate themselves into 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 when in their latent state.

When the virus becomes "active" for whatever reason, it begins reproducing and its progeny viruses 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, antibiotic drops or ointment might be used preventatively to reduce chances of a bacterial infection developing in the area of viral infection. This is because when the cornea is eroded, it becomes more vulnerable to a bacterial infection.

If the eye pressure (intraocular pressure) rises due to internal swelling (inflammation) of the eye or direct herpes virus infection of the trabecular meshwork (the internal drainage channels within the eye), a pressure-lowering medication will also be necessary.

Inflammation of any of the tissues of the eye may be so significant as to require anti-inflammatory medications such as steroids. While steroids can control inflammation very well, they can also compromise the immune system, so most often they are carefully introduced once the active viruses are well controlled by antiviral medication. 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 is aimed at reducing the chances of scarring, eye pressure problems, and direct damage to the eye tissues.

What is the prognosis of herpes eye infections?

Thankfully, the majority of HSV eye infections is limited to the cornea and resolve within a couple of weeks with antiviral therapy, leaving little or no permanent damage.

With HZV and shingles, the keratitis may resolve over a similar time frame. However, it is not uncommon for a painful burning sensation to linger in the area of the skin rash for months or even years. This is referred to as "post herpetic neuralgia" and sometimes responds to neurologic medications aimed at suppressing the pain nerves.

Both types of herpes eye infections can leave a residual corneal scar that can blur the vision. In some cases, this can be corrected with surgery. Damage to the corneal nerves can also lead to chronic, mild-to-moderate 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.

Source: http://www.rxlist.com

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 suppress 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. When we acquire herpes viruses, they incorporate themselves into 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 when in their latent state.

When the virus becomes "active" for whatever reason, it begins reproducing and its progeny viruses 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, antibiotic drops or ointment might be used preventatively to reduce chances of a bacterial infection developing in the area of viral infection. This is because when the cornea is eroded, it becomes more vulnerable to a bacterial infection.

If the eye pressure (intraocular pressure) rises due to internal swelling (inflammation) of the eye or direct herpes virus infection of the trabecular meshwork (the internal drainage channels within the eye), a pressure-lowering medication will also be necessary.

Inflammation of any of the tissues of the eye may be so significant as to require anti-inflammatory medications such as steroids. While steroids can control inflammation very well, they can also compromise the immune system, so most often they are carefully introduced once the active viruses are well controlled by antiviral medication. In some cases, the inflammation is chronic or recurring, requiring several rounds of steroid treatment.

Source: http://www.rxlist.com

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