What is ocular herpes?

You’ve no doubt heard of herpes before, but there a couple of types which affect different parts of the body. The types that affect the eye (causing ocular or eye herpes) are called the herpes simplex virus (HSV) and the varicella zoster virus (VZV). HSV is also associated with cold sores and VZV can also cause chicken pox or shingles.

Both of these viruses can lie dormant in the body for years, and often people won’t experience any issues with them. But when the virus becomes ‘activated’ it can lead to eye conditions known as herpes simplex keratitis and herpes zoster ophthalmicus.

What causes ocular herpes?

Herpes simplex virus

Within the HSV virus, there are two types that affect two main areas of the body:

  • Type 1 (HSV-1) – this is usually the cause of cold sores around the mouth and eye infections, such as herpes simplex keratitis.
  • Type 2 (HSV-2) – this causes genital herpes and can occasionally be linked to eye infections.

It’s very common for people to have type 1 herpes simplex – in fact, up to 90% of people in the UK have antibodies for HSV (seropositive), which means they have come into contact with the virus.1

It’s typically passed on by close contact, usually during childhood. Once you have herpes simplex, it does stay with you for life, but many people won’t experience any problems. Instead, it can lie inactive or dormant in the root of a nerve in the face, known as the trigeminal nerve.

Ocular herpes simplex happens when the virus ‘activates’ and travels down a branch of this nerve that joins to the eye, where it then causes an infection to the cornea (the clear area at the front of the eye that covers the coloured part of your eye). This type of eye infection is known as herpes simplex keratitis.

Varicella zoster virus

This type of the herpes virus also causes chicken pox and shingles. Once you’ve had chicken pox in childhood, the virus lies dormant in some of the nerve fibres found at the top of the spine and the brain.

Sometimes, when the body’s immune system is weakened (by other health problems or stress), it causes the dormant virus to ‘reactivate’ and multiply. 

Like the herpes simplex virus, herpes zoster makes its way from the nerve fibres in the spine and brain to the trigeminal nerve in the face. This usually causes shingles (an infection that causes a painful rash) or it can travel up the nerve to the eye, where it becomes inflamed. This type of eye infection is known as herpes zoster ophthalmicus.

Types of ocular herpes

Ocular herpes can affect your eye in different ways, depending on where the infection appears.

Ocular herpes simplex

Once the virus becomes active, ocular herpes simplex can affect:

Eyelids

As a result of the infection, the eyelids can become inflamed – a condition known as blepharitis.

Cornea

The cornea is the clear window at the front of the eye and is made up of a number of layers. Most cases of herpes simplex affect the very top layer of the cornea (known as epithelial keratitis), causing inflammation and sometimes ulcers.

In some cases, the infection can appear in the deeper layers of the cornea (the stroma), which is known as stromal keratitis. This type can be more serious as it can cause permanent scarring to the cornea, which can permanently affect vision.

Conjunctiva

Due to the infection on the cornea, the conjunctiva (the clear, thin skin that covers the white of the eye) can become inflamed and red – known as conjunctivitis.

Iris

The iris is the coloured part of the eye. In severe cases of herpes simplex, the iris can become infected and inflamed, leading to anterior uveitis.

Retina

The retina is the light-sensitive layer at the very back of the eye. In rare cases, herpes simplex can also cause inflammation of the retina, called acute retinal necrosis. This is more common in people with severely weakened immune systems.

Herpes zoster ophthalmicus

Once the virus becomes active, this type can affect:

Eyelid and skin

A rash with painful red blisters can appear on eyelid and skin around the affected eye. The eyelid might become swollen too.

Conjunctiva

The clear layer of skin overlaying the white of the eye (conjunctiva), can become infected, causing red eyes and sometimes discharge.

Cornea

This is the clear window at the front of the eye and is quite common to be affected to a varying degree. Infection or inflammation of the cornea is known as keratitis, and might be referred to as epithelial, nummular, disciform or endothelial keratitis depending on which layer of the cornea is affected.

Sclera

This is the name for the white of the eye and its top layer is referred to as the episclera. In around a third of cases, the episclera can be affected by the virus and become infected. Less commonly, the deeper layers of the sclera may be affected and lead to scleritis, which is a more painful condition.

Iris

As with herpes simplex, in severe cases the iris can become infected and inflamed, leading to anterior uveitis

Eye pressure

Rarely, a form of secondary glaucoma can occur as a result of the herpes zoster infection.

Retina

In rare cases, the retina can become infected with the herpes zoster virus leading to a condition called acute retinal necrosis. Or it can cause choroiditis, which is inflammation of the choroid (a layer of the eye behind the retina).

What are the signs and symptoms of ocular herpes?

Herpes simplex keratitis

This usually affects one eye, with common symptoms including:

  • Eye redness, usually around the front of the eye (cornea)
  • A gritty feeling in the eye
  • Pain or aching feeling in the eye
  • Sensitivity or discomfort to bright light (photophobia)
  • Watery eye
  • Blurry vision
  • Swelling around the eye
  • Reduced sensitivity of the cornea.

Herpes zoster ophthalmicus

In its early stages, people often experience a tingling or uncomfortable feeling on the forehead of one side of their face. After a few days a rash appears in this area, as well as the upper eyelid, made up of small, painful red blisters. People may also feel generally unwell.

  • Other eye symptoms can include:
  • Pain or discomfort
  • Redness
  • Discharge
  • Sensitivity or discomfort to bright light (photophobia)
  • A swollen or droopy eyelid.

How contagious is herpes in the eye?

Herpes simplex keratitis doesn’t usually spread to the other eye and it’s unlikely that you’d pass it on to another person. So you don’t need to worry about being contagious while you’re experiencing symptoms. However, the herpes simplex virus can be contagious, so if you have a cold sore you should try to avoid touching your eyes.

Herpes zoster ophthalmicus doesn’t usually spread to the other side of the face or eye and it’s rare to pass on to another person. But if the blisters from the rash weep, the fluid is contagious so could be passed on to someone else by touch. This could cause the other person to experience chicken pox (if they haven’t already had it) or shingles (if they were prone to it).

How do you treat ocular herpes?

Treatment for ocular herpes symptoms will depend on which part of the eye is affected.

Herpes simplex keratitis

Top layer of the cornea (epithelial keratitis)

This is usually treated with a prescribed anti-viral ointment or eye drops, applied several times a day for around two weeks. This works by preventing the virus from further multiplying so the infection can clear up.

Deep layer of the cornea (stromal keratitis)

This type is treated in the same way as epithelial keratitis, but your doctor might also recommend some steroid eye drops to reduce the inflammation and reduce the chance of scarring. They might also prescribe anti-viral tablets.

Herpes zoster ophthalmicus

If it’s caught early, within around 72 hours, then a GP might prescribe some anti-viral tablets to help reduce any potential complications in the eye.

Paracetamol or ibuprofen can help with any pain from the rash.

If the cornea is affected, an ophthalmologist (eye specialist) will be able to recommend the right treatment, which could include anti-viral drops, steroid drops and systemic anti-viral therapy.

The main aim in treating both herpes simplex keratitis and herpes zoster ophthalmicus is to make sure that the cornea stays in good condition, with minimal scarring. Scarring on the cornea can cause distorted vision, and in very advanced cases, can even lead to sight loss and may result in the need for a corneal graft (transplant). So it’s important to see your optician or GP as soon as possible in order to treat symptoms quickly.

References

1. College of Optometrists (2020). Herpes Simplex Keratitis (HSK). Available at: https://www.collegeoptometrists.org/guidance/clinical-management-guidelines/herpes-simplex-keratitis-hsk-.html [accessed March 2020]