Herpes Zoster Ophthalmicus (HZO), commonly known as shingles in the eye, is a reactivation of the Varicella-Zoster Virus (VZV) dormant since a chickenpox infection. This viral flare-up travels along the ophthalmic division of the trigeminal nerve, which supplies sensation to the eye and surrounding facial structures. Because of its direct route to the eye, HZO is considered a medical emergency requiring immediate attention. Prompt diagnosis and treatment are necessary to prevent severe and potentially permanent damage to the eye and vision.
The Timeline of Active Infection
The acute phase begins with a prodromal phase, characterized by localized pain, tingling, or burning sensations that can precede the visible rash by two to five days. This nerve pain is confined to the ophthalmic dermatome, involving the forehead, upper eyelid, and scalp.
Following this discomfort, a vesicular rash erupts, progressing from red spots to fluid-filled blisters over several days. The rash typically crusts over and begins to heal within one to two weeks, marking the end of the active skin infection. Ocular symptoms, such as inflammation of the conjunctiva (conjunctivitis) or the outer layer of the eye (episcleritis), usually appear during this active rash phase.
The acute viral activity and associated inflammation often subside within two to four weeks, especially with quick treatment. However, this timeline only accounts for the immediate viral phase and the healing of the skin lesions. The potential for inflammation to affect deeper eye structures means the illness can extend far beyond the initial month, sometimes leading to chronic or recurrent issues.
Immediate Medical Management
Timely medical intervention limits the duration and severity of the acute infection and reduces the risk of long-term damage. Treatment focuses on systemic antiviral medications to stop the virus from replicating and limit its spread to nerve and eye tissues. Oral antiviral drugs, such as valacyclovir or famciclovir, are typically prescribed for a seven- to ten-day course.
Starting this therapy within 72 hours of the skin rash onset is the most effective way to prevent ocular involvement and reduce nerve pain. Valacyclovir and famciclovir are often preferred over acyclovir due to their higher bioavailability and more convenient dosing schedule.
Supportive treatments are also administered to manage inflammation and pain. Topical steroid eye drops may be used to control inflammation inside the eye, such as uveitis or keratitis, but only under the close supervision of an ophthalmologist. Cycloplegic drops may also be used to dilate the pupil, which helps relieve pain caused by ciliary muscle spasm and prevent iris-lens adhesions.
Potential Long-Term Eye and Nerve Damage
Although the acute viral phase resolves in a few weeks, the consequences of nerve and tissue damage can persist for months or even years. One common chronic issue is Postherpetic Neuralgia (PHN), which is nerve pain that continues after the skin rash has healed. PHN can be debilitating and may require specialized pain management.
In the eye, the virus can cause long-term ocular sequelae that demand ongoing management. Chronic inflammation of the cornea (keratitis) is common and can lead to permanent scarring and vision loss. This inflammation can be recurrent, requiring long-term, low-dose topical steroid treatment that must be carefully monitored.
Damage to the corneal nerves can also result in neurotrophic keratitis, where the cornea loses sensation, making it vulnerable to breakdown and secondary infection. Inflammation inside the eye (uveitis) can also lead to secondary glaucoma by elevating intraocular pressure, necessitating continuous monitoring and treatment. These chronic complications are the primary reason patients with shingles in the eye experience an extended recovery period and require regular follow-up for years.
Preventing Future Episodes
Reducing the risk of future episodes focuses primarily on vaccination. The recombinant zoster vaccine is recommended for immunocompetent adults aged 50 years and older to prevent shingles and its complications. It is highly effective and significantly reduces the risk of long-term nerve pain.
For individuals who have already experienced shingles in the eye, the vaccine is still recommended to boost immunity against the virus. However, vaccination may temporarily increase the risk of a recurrent episode of HZO immediately following the shot. Patients with a history of HZO are advised to have close ophthalmic monitoring after receiving the vaccine.
Beyond vaccination, consistent follow-up with an ophthalmologist is necessary, even after initial recovery. This is important for patients who had significant corneal or internal eye involvement during the acute phase. Ongoing monitoring allows for the early detection and management of delayed complications like corneal scarring, glaucoma, or recurrent inflammation.