Herpes simplex keratitis is a corneal infection caused by herpes simplex virus type 1 (HSV-1) — the same virus responsible for cold sores around the mouth. After a primary infection in childhood, the virus lies dormant in the trigeminal nerve and can reactivate at any point in life, traveling along the nerve to the cornea. The most recognizable form is the “dendritic ulcer” — a branching, tree-like pattern on the corneal surface visible with fluorescein staining under a slit lamp.
HSV keratitis is typically unilateral (one eye), painful, and accompanied by light sensitivity and decreased vision. Repeated episodes can scar the cornea over time, which is why early diagnosis and prompt antiviral therapy are essential. For patients with frequent recurrences, daily oral antiviral suppression has been shown in landmark trials to reduce recurrence by about half.
Critical warning: if you have had cold sores and develop a painful red eye, do not use any leftover steroid eye drops. Topical steroids without antiviral coverage can dramatically worsen herpes keratitis. Get evaluated first.
Symptoms
Often more painful than typical pink eye, with a deep aching or burning sensation in one eye.
Bright lights become difficult to tolerate due to inflammation of the cornea and inside of the eye.
Decreased vision in the affected eye, sometimes dramatic if the dendritic lesion is in the central cornea.
Almost always affects only one eye, unlike viral or bacterial conjunctivitis which often spread to both.
Many patients have a history of oral herpes outbreaks, recent stress, illness, or sun exposure.
A subtle but important clinical sign — the cornea may feel less sensitive than the unaffected eye.
Dr. Patel is a Diplomate of the American Board of Optometry with deep experience in corneal disease and antiviral management.
We follow HSV patients longitudinally to monitor for recurrence, manage suppression therapy, and adjust treatment as needed.
For severe stromal disease or vision-threatening complications, we coordinate seamlessly with corneal specialists.
Frequently Asked Questions
Most ocular HSV infections are caused by HSV-1, the same virus that causes cold sores. Roughly half of all adults carry HSV-1, often having acquired it as children through casual contact. The virus lies dormant in nerve tissue and can reactivate to cause cold sores, oral herpes, or — less commonly — corneal infection. You did not necessarily catch it recently, and it is not a sexually transmitted infection in this context.
Yes, recurrence is the defining feature of ocular HSV. Once the virus is established in the trigeminal ganglion, it can reactivate periodically — triggered by stress, illness, sunlight, or weakened immunity. About 25 percent of patients have a second episode within 2 years, and recurrent episodes are why long-term suppressive antiviral therapy is sometimes recommended.
Repeated infections can scar the cornea and cause permanent vision loss. HSV keratitis is the leading infectious cause of corneal blindness in the United States. Prompt antiviral treatment shortens episodes and reduces scarring, and long-term suppression therapy reduces recurrence by about half in patients with frequent episodes.
Steroid drops without antiviral coverage can dramatically worsen herpes keratitis and lead to corneal melting or perforation. This is one of the most important reasons to get an accurate diagnosis before treating any red eye. Steroids do have a role in herpes care for stromal disease, but only in combination with antivirals and under careful supervision.
For active dendritic ulcers, Dr. Patel typically prescribes oral antivirals (acyclovir, valacyclovir, or famciclovir) and/or topical antiviral drops or gels. Treatment usually lasts 1 to 2 weeks for the active episode. For patients with frequent recurrences, daily suppressive oral antiviral therapy can dramatically reduce future episodes and protect long-term vision.