Eye herpes, also known as ocular herpes or herpes simplex keratitis, is an eye infection caused by the herpes simplex virus (HSV).
Approximately 24,000 new cases of eye herpes are diagnosed in the United States each year, and an estimated 1 million new cases per year are diagnosed globally.1 Men are slightly more likely to get eye herpes than women.
The area of the eye affected depends on the type of eye herpes. Usually, the cornea (the normally clear dome that covers the front part of the eye) is affected, but eye herpes can reach the inside of the eye or the retina (the thin layer of tissue that lines the back of the eye on the inside).
Eye herpes can also cause inflammation of the eyelids, the conjunctiva (the clear tissue covering the white part of the eye and the inside of the eyelids), or the iris (the colored part of the eye that controls the amount of light entering the eye). Eye herpes cannot be cured, but it can be managed.
Types of Eye Herpes
There are two main types of eye herpes. Epithelial keratitis is the more common form of eye herpes, but stromal keratitis is more serious and can lead to blindness.
Epithelial Keratitis
Epithelial keratitis accounts for an estimated 50%–80% of all ocular herpes infections.3 HSV epithelial keratitis affects the outermost layer of the cornea called the epithelium. The virus destroys corneal epithelial cells as it replicates.
Stromal Keratitis
Stromal keratitis affects the deeper layers of the cornea called the stroma. It is caused by a combination of viral infection and compromised immune mechanisms. Stromal keratitis can result in corneal scarring and loss of vision.4
There are two types of stromal keratitis: stromal keratitis without ulceration and HSV stromal keratitis with ulceration.5
Stromal keratitis without ulceration:
It is thought to occur from viral proteins being left behind in the cornea even after the infection has cleared up.
The body produces an inflammatory response to these proteins, leading to stromal keratitis without necrosis (the death of tissue).
HSV stromal keratitis with ulceration:
It is less common than stromal keratitis without ulceration.
It is also an immune response to the proteins left behind in the stroma.
Instead of inflammation, tissue necrosis occurs, resulting in ulceration (the formation of an open sore) and destruction of the stromal bed.
Herpes Zoster Ophthalmicus
The herpes zoster virus (which causes chickenpox and shingles) can also cause eye herpes.6
Like the herpes simplex virus, the herpes zoster virus stays dormant in the body once contracted, and you can have flare-ups, periods of reactivation and worsening symptoms.
Symptoms of herpes zoster ophthalmicus are similar to HSV eye infections but can also include:
Redness, rash, or sores on the eyelids and around the eyes (especially on the forehead) similar in appearance to poison ivy or poison oak blisters that turn into scabs over one to two weeks; a milder rash in younger people than in older people
Swelling and cloudiness of the cornea
Flu-like symptoms (low-grade fever, generally feeling unwell)
Tingling and numbness in the forehead before the rash appears
Eye Herpes Symptoms
Symptoms of eye herpes include:
Pain in and around (usually) only one eye
Redness of the eye
Decreased vision
Feeling of dirt or grit in the eye
Overflowing tears
Pain when looking at bright light
Swelling or cloudiness of the cornea
Discharge from the eye
Headache7
Rash with blisters on the eyelid(s)
Painful sore on eyelid or eye surface
Eye Herpes vs. Pink Eye
Symptoms such as redness, pain, eyelid swelling, or discharge from the eye can occur with both eye herpes and pink eye (conjunctivitis), so eye herpes is sometimes mistaken for pink eye.8
Pink eye can be caused by a bacterial infection, a viral infection, allergies, or chemical exposure, while eye herpes is always caused by a virus.
Pink eye can affect one or both eyes. While it is possible for eye herpes to occur in both eyes, it usually appears in just one eye. If the infection recurs within a year, it's more likely to be viral rather than bacterial, or it may be from chemical exposure.
Because the symptoms for eye herpes and pink eye are similar and both can be caused by a virus, it is important to see a healthcare professional to get a proper diagnosis. Doing so will ensure the most effective treatment for either condition.
Healthcare professionals usually make a diagnosis of pink eye without doing a viral or bacterial culture. Occasionally, this leads to a missed eye-herpes diagnosis. If you have been diagnosed with pink eye, but it doesn't seem to be clearing up with or without treatment, book a follow-up with your healthcare professional to rule out eye herpes.
Causes
Eye herpes is caused by the herpes simplex virus (HSV). While there are two forms of HSV that can cause eye herpes, it is usually caused by HSV-1, the same virus that causes oral herpes (cold sores or fever blisters).9
While HSV-1 can be transmitted directly to the eye such as by touching a cold sore on the mouth and then touching the eye, eye herpes is often the result of a flare-up of an earlier HSV-1 infection in another part of the body (usually the mouth.)
HSV-1 is very common. Approximately 3.7 billion people under age 50 worldwide have HSV-1 infection.5 Seropositivity (antibodies found in the blood for a particular infection) for HSV-1 has been reported in 65% of Americans.10
Most people in the United States will contract HSV-1, usually in childhood. Many people are unaware they carry the virus and it can remain dormant (inactive and asymptomatic) in the body indefinitely.6
A flare-up, or breakout, can occur if the virus starts to multiply or moves from one area of the body to another. Flare-ups can be random, or they can be triggered by:11
Illness
Fever
Weather (strong sunlight or cold wind)
Ultraviolet (UV) light exposure, including tanning beds
An eye injury
Stress
Menstrual periods
A weakened immune system (can be caused by certain medical conditions and treatments such as chemotherapy)
Some medications
HSV is typically infectious during the five to 10 days the skin lesions are healing, as well as during asymptomatic shedding in saliva.1 Unlike genital herpes, eye herpes is not sexually transmitted.
There are some key differences between HSV-1 and HSV-2:12
HSV-1
Mainly transmitted by oral-to-oral contact and causes mouth herpes (but can cause genital herpes through oral to genital contact)
Is common, affecting approximately 3.7 billion people under age 50 (67%) globally
Usually acquired during childhood
HSV-2
Almost exclusively transmitted through genital-to-genital contact (sexually transmitted) and causes genital herpes (genital or anal area)
Is less common, affecting approximately 491 million people aged 15–49 (13%) globally
Usually transmitted once sexually active
Diagnosis
Eye herpes is usually diagnosed by eye specialists called ophthalmologists or optometrists.
The eye specialist will take a health history and have a discussion of symptoms, including the items in the lists that follow.1
Ocular symptoms:
Degree of pain
Redness
Discharge
Presence or absence of blurred vision
Whether you're experiencing photophobia (sensitivity to light)
When the symptoms started and how often they occur
Circumstances surrounding the onset of symptoms
Contact lens history:
Whether you wear contact lenses
When you wear contacts and for how long at a time
Whether you wear contacts overnight
Type of contact lens
The lens solution used
Contact lens hygiene practices and routines
Whether you use tap water to rinse your contact lenses
Whether you swim, use a hot tub, or shower while wearing contact lenses
Review of other ocular and medical history:
Risk factors, such as previous HSV keratitis
Review of past or present eye conditions
Review of other past and present medical problems and conditions
Current and recently used medications, including medications for the eyes
Medication allergies
The eye-care specialist will also perform an eye exam that includes checking for light sensitivity, vision, and general health.
Diagnostic tests and procedures the eye specialist may use include:1
Measurement of visual acuity: Tests how well you see shapes and details
External examination: Checks for things that can be seen on the outside of the eye, such as discharge, corneal sensation, and general appearance of the eyes, face, and eyelids
Slit-lamp biomicroscopy: Using a microscope that magnifies the surface and inside of the eye
Fluorescein eye stain test: A close examination of the cornea after dye is placed on the surface of the eye
Culture sample: Taking a culture swab (a small collection of cells) and sending it to a lab for further examination
