ConditionEyes & vision
Viral Keratitis
Viral keratitis is an infection of the cornea, the clear front window of the eye, caused by a virus. The most common and important cause is herpes simplex virus (HSV), which can recur and scar the cornea, making it a leading infectious cause of corneal blindness in developed countries. Shingles (varicella-zoster) and adenovirus are other causes. Symptoms include eye pain, redness, tearing, light sensitivity and blurred vision. It needs prompt eye care with antiviral treatment; steroid drops alone can make herpes keratitis much worse.
Also called: Herpes simplex keratitis, herpetic keratitis, HSV keratitis, dendritic keratitis, herpes zoster keratitis, adenoviral keratoconjunctivitis
At a glance
- What it is
- A viral infection and inflammation of the cornea.
- Main causes
- Herpes simplex virus (most important), varicella-zoster (shingles), adenovirus.
- Symptoms
- Eye pain, redness, watering, light sensitivity, blurred vision, feeling of grit; usually one eye with herpes.
- Diagnosis
- Slit-lamp exam with fluorescein dye showing branching (dendritic) ulcers; sometimes swab PCR.
- Treatment
- Antiviral eye gel or drops and/or oral antivirals; steroids only under specialist supervision for some forms.
- Recurrence
- Herpes keratitis often recurs; long-term oral antivirals reduce repeat episodes.
When to get help
Call 911 or go to the ER
- Sudden severe eye pain with significant vision loss
See a doctor within a day or two
- A painful red eye with blurred vision and light sensitivity, especially with a history of cold sores or eye herpes (see an eye doctor the same day)
- A shingles rash on the forehead, around the eye or on the tip of the nose
- A red, painful eye in a contact lens wearer
- Worsening eye symptoms while using steroid eye drops
Book a routine appointment
- Recurrent episodes of red, irritated eye in someone with previous herpes keratitis
- Reduced vision or glare after a past corneal infection
Usually safe to manage at home
- Both eyes watery, gritty and pink during a cold, without significant pain or vision loss (likely viral conjunctivitis), while monitoring for worsening
How viral keratitis develops
The cornea is the transparent outer layer at the front of the eye. Viruses can infect its surface (epithelium) or deeper layers (stroma and endothelium).
- Herpes simplex virus (HSV-1) usually reaches the eye after an earlier infection elsewhere, such as cold sores. The virus then lies dormant in the trigeminal nerve and can reactivate, often triggered by stress, fever, sun exposure, illness or eye surgery.
- Varicella-zoster virus causes keratitis as part of shingles affecting the ophthalmic nerve (herpes zoster ophthalmicus).
- Adenovirus causes epidemic keratoconjunctivitis, a highly contagious "pink eye" that can leave small spots on the cornea.
Types of herpes simplex keratitis
| Type | Layer | Features |
|---|---|---|
| Epithelial (dendritic) | Surface | Branching ulcer, the most common form; caused by live virus |
| Stromal | Middle layer | Immune reaction; corneal haze, scarring, new blood vessels |
| Endothelial | Inner layer | Corneal swelling and blurred vision |
| Neurotrophic | Surface | Non-healing ulcer from loss of corneal sensation after repeated episodes |
Symptoms
- eye pain or discomfort
- redness
- watering
- sensitivity to light (photophobia)
- blurred vision
- foreign body or gritty feeling
- usually in one eye with herpes
- reduced corneal sensation (often after repeated episodes)
- blisters on the eyelid or a rash on the forehead with shingles
Diagnosis
An eye care professional examines the eye with a slit lamp. Fluorescein dye highlights corneal ulcers; herpes typically shows a characteristic branching dendritic pattern. Corneal sensation is tested. Swabs for PCR or culture are sometimes taken in unclear cases.
It is important to distinguish viral keratitis from bacterial and fungal keratitis, acanthamoeba keratitis in contact lens wearers, and viral conjunctivitis, which affects mainly the surface of the eye and eyelid lining.
Treatment
Herpes simplex keratitis
- epithelial disease: topical antivirals such as ganciclovir gel or trifluridine drops, or oral antivirals (acyclovir, valacyclovir)
- stromal disease: topical steroids to control immune inflammation, always combined with antiviral cover and supervised by an eye specialist
- endothelial disease: steroids with antiviral cover
- neurotrophic ulcers: lubrication, bandage contact lenses, special growth factor drops, or eyelid procedures
- long-term preventive oral antivirals for people with frequent recurrences or stromal disease, which reduce recurrences by about half
Herpes zoster keratitis
Oral antivirals started within 72 hours of the shingles rash, plus eye-specific treatment. The shingles vaccine helps prevent herpes zoster ophthalmicus.
Adenoviral keratoconjunctivitis
Usually resolves on its own over 2 to 3 weeks. Cool compresses and artificial tears help; steroid drops are sometimes used for persistent corneal spots. It is highly contagious: wash hands and avoid sharing towels.
Complications
- corneal scarring and reduced vision
- corneal thinning and perforation (rare)
- glaucoma and uveitis
- secondary bacterial infection
- need for corneal transplant in severe cases
Prevention of recurrence
- avoid touching eyes during cold sore outbreaks; wash hands
- protect eyes from strong sunlight
- long-term antiviral tablets if recommended
- prompt treatment at the first sign of recurrence
- tell any eye surgeon about a history of eye herpes
Frequently asked questions
What is viral keratitis?
Viral keratitis is an infection of the cornea caused by a virus, most often herpes simplex. It causes eye pain, redness, light sensitivity, watering and blurred vision, and needs prompt treatment to prevent scarring.
What does herpes keratitis look like?
The eye is usually red and watery, and the person may notice pain and light sensitivity. An eye doctor using fluorescein dye sees a branching (dendritic) ulcer on the cornea, which is characteristic of herpes simplex.
Is viral keratitis contagious?
Herpes keratitis comes from a reactivated virus and is not usually spread from the eye, though herpes can spread through direct contact with active sores. Adenoviral keratoconjunctivitis is highly contagious through hands, towels and surfaces.
Can herpes keratitis cause blindness?
It can if untreated or frequently recurring, because repeated inflammation scars the cornea. With prompt antiviral treatment, specialist follow-up and preventive medicine when needed, most people keep good vision.
Sources
This guide was written from current patient and clinical guidance, including:
- American Academy of Ophthalmology: Herpes simplex virus keratitis, A Treatment Guideline (2014)
- American Academy of Ophthalmology: EyeWiki, Herpes Simplex Keratitis; Adenoviral Keratoconjunctivitis
- National Eye Institute: Herpes eye disease (facts)
- CDC: Shingles complications, herpes zoster ophthalmicus
- MedlinePlus: Keratitis