Herpes Simplex Keratitis (Eye Herpes)

How the infection happens

Most adults carry herpes simplex virus type 1 (HSV-1), usually picked up in childhood. After the first infection, the virus lies dormant in the trigeminal nerve, which supplies the face and eye. It can reactivate and travel down the nerve to the cornea. Less commonly, the first infection affects the eye directly. HSV-2, the usual cause of genital herpes, can infect the eyes of newborns during birth.

Reactivation triggers include:

• stress and fatigue
• fever and illness
• strong sunlight and UV exposure
• eye injury or surgery (including laser eye surgery)
• weakened immunity
• some medicines, including steroid eye drops

Types of herpes keratitis

Herpes can also cause blepharitis (eyelid blisters), conjunctivitis, uveitis (inflammation inside the eye), and rarely retinal infection.

Symptoms

• red eye, usually one side
• eye pain or a gritty, foreign-body feeling
• watering
• sensitivity to light
• blurred vision
• sometimes a cold sore or blisters on the eyelid or nearby skin
• reduced feeling in the cornea after repeated episodes

Diagnosis

An eye doctor (ophthalmologist or optometrist) uses a slit lamp microscope. Fluorescein dye stains the corneal surface and reveals the characteristic branching dendritic ulcer. Corneal sensation is tested, since it is often reduced. Swabs for PCR testing may be taken if the diagnosis is uncertain.

Herpes keratitis can be mistaken for ordinary conjunctivitis. Steroid eye drops used for other conditions can make herpes epithelial keratitis dramatically worse, which is why a red, painful eye should be examined before steroid drops are used.

Treatment

Epithelial (surface) keratitis

• Antiviral eye gel or drops: ganciclovir gel or trifluridine drops, used several times a day.
• Oral antivirals: acyclovir, valacyclovir or famciclovir, often as effective as drops.
• Debridement: gently removing infected surface cells may speed healing.

Stromal keratitis and endotheliitis

• Steroid eye drops under close specialist supervision to reduce inflammation, always combined with oral antivirals.
• Treatment may continue for weeks to months with gradual tapering.

Preventing recurrences

Long-term oral acyclovir (daily) substantially reduces recurrences of eye herpes. It is commonly offered to people with repeated or stromal disease, and around eye surgery.

Severe scarring

Rigid contact lenses can improve vision with irregular scarring. Corneal transplantation may be needed for severe scarring, with antivirals to protect the graft.

Complications

• corneal scarring and permanent vision loss
• corneal ulcer and thinning, rarely perforation
• glaucoma from inflammation or steroids
• secondary bacterial infection

Prevention

• avoid touching cold sores, and wash hands before touching your eyes
• do not share towels or eye makeup during a cold sore outbreak
• stop contact lens wear during an eye infection
• use sunglasses and manage known triggers
• take preventive antivirals as advised if you have frequent recurrences

Frequently asked questions

What are the symptoms of herpes in the eye?

Common symptoms are a red, painful, watery eye, light sensitivity, blurred vision and a gritty feeling, usually in one eye. There may be blisters on the eyelid or a cold sore nearby.

Is herpes simplex keratitis contagious?

The virus can spread through direct contact with active sores or eye discharge. Most adults already carry HSV-1, so the main concern is avoiding spreading it to babies and people who have never been infected. Wash hands often during an outbreak.

Can eye herpes cause blindness?

Repeated or deep infections can scar the cornea and reduce vision, and herpes keratitis is a leading infectious cause of corneal blindness in developed countries. Prompt treatment and preventive antivirals greatly reduce this risk.

Does eye herpes come back?

It often does, because the virus stays dormant in nerves. Stress, illness, sunlight and eye surgery can trigger recurrences. Daily oral antiviral medicine reduces how often it returns.