Herpes Simplex Keratitis

Herpes Simplex Keratitis (“cold sore of the eye”) is a common, recurrent viral infection affecting the eyes. It can cause inflammation and scarring of the cornea (the clear window of the eye). Most people are exposed to the virus in their childhood, and in many people the virus remains dormant in the trigeminal nerve in our face. However, if the virus reactivates, it can travel down a branch of the nerve to the mouth causing cold sores, and in some cases it can travel down a branch of the nerve to the eye to cause episodes of active eye infection. Infection of the cornea is called keratitis. Often people who get active eye infections have a previous history of cold sores.

When just the top layer of the cornea is infected, it is called epithelial keratitis. But if the deeper layers are involved, it is called stromal keratitis. Stromal keratitis is more likely to cause permanent scarring. Sometimes deeper structures, such as the retina or iris are involved.

It is thought that stress-related factors such as sunburn, fever, menstruation, major dental or surgical procedures and trauma may be associated with recurrences.

Herpes Simplex Keratitis affects one eye, and may cause any of the following:

• Redness
• Glare sensitivity (photophobia)
• Watering of the affected eye
• Foreign body sensation
• Blurred vision

These symptoms are common to several other eye conditions and should always be investigated.

Investigations include any of the following:

• Vision assessment.
• Slit lamp examination with some stain on the cornea (This will show up any corneal defects, and with HSK a typical “dendritic” ulcer is seen.).
• Dilated eye examination – to look for any retinal involvement.

The treatment for herpetic eye disease is dependent on which part of the eye is involved. It can include:

• Antiviral eye ointment (for Herpes Simplex Keratitis). This does not kill the virus but stops it from multiplying further until the infection clears, and is generally used for several weeks.
• In some cases oral antivirals can be used.
• Steroid eye drops (for stromal keratitis). Steroid drops can be used with antiviral ointment to reduce inflammation and reduce scarring. It is important that the antiviral is continued while using steroid drops.

There should be no contact lens wear until the cornea has healed.

Epithelial keratitis tends to respond well to treatment and resolves with little or no scarring. Stromal keratitis can result in corneal scarring and reduced vision despite treatment.

Recurrent episodes of active infection can develop in some people and make existing scarring worse. This can occur between weeks and many years after the first active infection. It is suggested that about 50% of people will have a recurrence within 10 years of the first. If recurrences are frequent or severe, the use of daily oral antivirals may be recommended to prevent episodes of active infection. Early treatment with antivirals helps to minimise corneal damage.