Keratitis Herpetica - Causes, Treatment & When to See a Doctor

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What is Keratitis Herpetica?

Keratitis herpetica, also called herpes simplex keratitis (HSK), is an infection of the cornea—the clear, dome‑shaped front surface of the eye—caused by the herpes simplex virus (HSV). The virus most often involved is HSV‑1, the same pathogen that produces cold sores around the mouth, although HSV‑2 (typically linked to genital infections) can occasionally affect the eye.

When HSV invades corneal tissue it can cause inflammation, ulceration, scarring, and, if untreated, permanent visual loss. The condition may present as a single episode or recur many times over a person’s life, because HSV establishes a lifelong dormant infection in the trigeminal ganglion and can reactivate under certain triggers.

According to the Mayo Clinic, keratitis herpetica is the leading cause of corneal blindness in the United States and accounts for up to 40% of infectious corneal disease worldwide.

Common Causes

Herpes simplex keratitis is not caused by external “conditions” in the same way as bacterial conjunctivitis; instead, several factors increase the likelihood that dormant HSV will reactivate and attack the cornea. The most important triggers include:

• Prior HSV infection – Most adults carry the virus after a childhood cold‑sore episode.
• Immunosuppression – HIV/AIDS, organ transplantation, chemotherapy, or systemic steroids lower viral control.
• Local ocular trauma – Scratches, contact‑lens wear, or eyelid surgery disturb the corneal surface.
• Ultraviolet (UV) light exposure – Sunlight or tanning beds can reactivate HSV.
• Stress or fatigue – Physical or emotional stress alters immune function.
• Fever or other viral illnesses – Concurrent infections can precipitate reactivation.
• Hormonal changes – Pregnancy or menstrual cycle fluctuations may play a role.
• Dry eye disease – Chronic ocular surface irritation reduces local defenses.
• Use of topical corticosteroids without antiviral cover – Steroids blunt inflammation but can allow unchecked viral replication.
• Contact lens misuse – Poor hygiene, overwearing, or contaminated lenses provide a portal for HSV entry.

Associated Symptoms

The clinical picture varies with the type of corneal involvement. The three classic patterns are epithelial keratitis, stromal keratitis, and endothelial (disciform) keratitis. Common symptoms across these forms include:

• Redness – Usually localized to the affected eye.
• Eye pain – Can range from mild irritation to severe throbbing.
• Blurred or decreased vision – Especially if the central cornea is involved.
• Photophobia (light sensitivity) – Discomfort in bright environments.
• Tearing or watery discharge.
• Foreign‑body sensation – The feeling of something in the eye.
• Recurrent episodes – Often preceded by a prodrome of tingling or itching in the eye.
• Corneal ulcer – An open sore that may be seen with a fluorescein dye exam.
• Scarring or opacities – Seen in chronic or recurrent disease, may cause permanent visual deficits.

When to See a Doctor

Prompt ophthalmologic evaluation is crucial because untreated herpes keratitis can quickly progress to scarring and vision loss. Seek medical attention if you notice any of the following:

• Sudden onset of eye redness, pain, or blurred vision lasting more than 24 hours.
• Persistent photophobia that interferes with daily activities.
• Visible white or gray spots on the cornea (ulcer or dendritic lesions).
• Recurrent episodes of eye irritation after a known cold‑sore outbreak.
• History of HSV infection combined with new eye symptoms.
• Any loss of visual acuity (even mild) that does not improve within a day.

If you belong to a high‑risk group—such as immunocompromised patients, contact‑lens wearers, or those on chronic steroids—don’t wait; schedule an exam as soon as symptoms appear.

Diagnosis

Diagnosing herpes simplex keratitis relies on a combination of clinical examination and, when needed, laboratory testing.

Clinical Evaluation

1. History taking – The physician asks about prior cold sores, immunosuppressive conditions, recent eye trauma, or UV exposure.
2. Slit‑lamp biomicroscopy – A high‑magnification microscope equipped with a bright light lets the doctor view the cornea in detail. Typical findings include:
• Dendritic lesions – Branching, fern‑like ulcerations characteristic of epithelial keratitis.
• Geographic ulcers – Larger, irregular lesions suggesting deeper involvement.
• Stromal infiltrates – Inflammatory plaques within the corneal stroma (mid‑layer).
• Disciform edema – Swelling of the endothelium and posterior stroma.
3. Fluorescein staining – A drop of fluorescein dye highlights epithelial defects; the pattern helps differentiate HSV from other causes.
4. Visual acuity testing – Baseline measurement to monitor recovery.

Laboratory Tests (when needed)

• Polymerase chain reaction (PCR) of a corneal scrape – Highly sensitive for detecting HSV DNA.
• Viral culture – Less commonly used because it is slower.
• Serology – Blood tests for HSV antibodies are generally not helpful for acute diagnosis but may support a history of infection.

Treatment Options

Therapy is aimed at eradicating viral replication, controlling inflammation, and preventing scarring. Treatment is individualized based on the stage and severity of the disease.

Antiviral Medications

• Topical antiviral ointments (e.g., trifluridine 1% cream) – Used for mild epithelial disease; applied 5‑9 times daily for 7‑10 days.
• Topical ganciclovir gel 0.15% – Often preferred because it causes less epithelial toxicity; applied 5 times daily.
• Oral antivirals – Acyclovir 400 mg 5×/day, valacyclovir 500 mg 3×/day, or famciclovir 250 mg 3×/day for 7‑10 days. Oral therapy is recommended for stromal disease, ulcerated lesions, or recurrent episodes.

Anti‑Inflammatory Therapy

• Topical corticosteroids (e.g., prednisolone acetate 1%) – Only started after antiviral coverage is established, and never as monotherapy. Used to reduce stromal inflammation, typically tapered over weeks.
• Non‑steroidal anti‑inflammatory drops (NSAIDs) – Occasionally used for pain, but they can delay epithelial healing and are generally avoided in active ulceration.

Adjunctive Measures

• Patching or bandage contact lenses – May promote healing of superficial ulcers under close supervision.
• Lubricating artificial tears – Reduce discomfort and maintain a moist ocular surface.
• Oral analgesics – Acetaminophen or ibuprofen for pain control.

Management of Recurrent Disease

Patients with frequent recurrences (≥2 episodes per year) often benefit from long‑term suppressive therapy:

• Valacyclovir 500 mg once daily or acyclovir 400 mg twice daily for 6‑12 months, then reassessed.

When Surgery Is Needed

Severe stromal scarring, persistent epithelial defects, or corneal perforation may require surgical intervention such as corneal transplantation (penetrating keratoplasty) or lamellar keratoplasty. These procedures are performed by corneal specialists after the infection is fully controlled.

Prevention Tips

While HSV cannot be eradicated, recurrence risk can be sharply reduced by lifestyle adjustments and eye‑care practices.

• Maintain good hand hygiene – Wash hands before touching eyes or handling contact lenses.
• Avoid sharing towels, pillowcases, or cosmetics that may harbor the virus.
• Use UV‑blocking sunglasses whenever outdoors, especially after a known HSV outbreak.
• Manage stress – Regular exercise, adequate sleep, and relaxation techniques lower reactivation chances.
• Control systemic illnesses – Keep diabetes, HIV, and other immune‑modulating conditions well managed.
• Proper contact‑lens care – Follow the manufacturer’s cleaning schedule, replace lenses as recommended, and avoid overnight wear unless approved.
• Limit steroid use – Do not use over‑the‑counter steroid eye drops without a doctor’s prescription; if steroids are needed, ensure concurrent antiviral therapy.
• Consider prophylactic antivirals – For patients with frequent recurrences, discuss long‑term suppressive therapy with an ophthalmologist.

Emergency Warning Signs

Key Take‑aways

• Keratitis herpetica is a viral infection of the cornea caused by HSV, most often HSV‑1.
• Reactivation triggers include UV light, stress, immunosuppression, ocular trauma, and contact‑lens misuse.
• Typical symptoms are eye redness, pain, photophobia, tearing, and blurred vision; dendritic ulcers are a hallmark sign.
• Prompt evaluation by an eye‑care professional—preferably an ophthalmologist—is essential to prevent scarring and permanent vision loss.
• Treatment combines topical or oral antivirals with carefully timed corticosteroids; chronic suppressive therapy can reduce recurrences.
• Prevention focuses on good hygiene, UV protection, stress management, and proper contact‑lens care.
• Red‑flag emergency signs require immediate emergency‑room care.

For more detailed information, consult reputable sources such as the CDC, NIH, and the Cleveland Clinic.

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