Herpes Zoster Ophthalmicus
Herpes Zoster Ophthalmicus (HZO), commonly known as shingles, is a viral disease characterized by a unilateral painful skin rash in one or more dermatome distributions of the fifth cranial nerve (trigeminal nerve), shared by the eye and ocular adnexa. HZO occurs typically in older adults but can present at any age and occurs after reactivation of latent varicella-zoster virus (VZV) present within the sensory spinal or cerebral ganglia.
HZO is caused by the varicella-zoster virus (VZV) which has re-activated from its dormant status in the dorsal ganglion cells of the central nervous system. From there, it may travel along neurons to the sensory axons of the skin to form vesicular lesions.
Herpes zoster frequently involves the ophthalmic division of the trigeminal nerve. It presents with malaise, fever, headache, and periorbital burning and itching. These symptoms may precede the eruption by a day or more. The rash is initially vesicular, quickly becoming pustular and then crusting. Involvement of the tip of the nose or the lid margin predicts involvement of the eye.
Signs and symptoms
Ocular signs include conjunctivitis, keratitis, episcleritis, and anterior uveitis, often with elevated intraocular pressure. Recurrent anterior segment inflammation, neurotrophic keratitis, and posterior subcapsular cataract are long-term complications. Optic neuropathy, cranial nerve palsies, acute retinal necrosis, and cerebral angiitis occur infrequently. HIV infection is an important risk factor for herpes zoster ophthalmicus and increases the likelihood of complications.
Herpes zoster is an acute, painful, vesicular eruption distributed along a single dermatome and is associated with a prodrome of fever, malaise, headache, and pain in the dermatome. The vesicles typically crust and will heal within 2-6 weeks.
- Visual acuity with the best correction
- External examination of eyelids, periocular skin, and scalp.
- Measurement of intraocular pressure
- Slit-lamp biomicroscopy of the anterior segment with special attention to any staining cornea defects, stroma opacities, cornea vascularization, keratic precipitates, and anterior chamber cell and flare.
- Dilated examination of the lens, macula, peripheral retina, optic nerve, and vitreous.
Dermatome distribution pain and rash with associated ocular findings strongly suggest HZO. Corneal epithelial defects, decreased corneal sensation, and ocular inflammation in any of the layers of the eye also correlate with the diagnosis. HZO iritis is frequently associated with high intraocular pressure.
Cornea sensation should be tested prior to the instillation of anesthetic drops. This can be accomplished with a Cochet-Bonnet Esthesiometer or with a fine wisp of a cotton-tip applicator. Decreased sensation is very suspicious for herpes simplex virus (HSV). Using fluorescein, cornea epithelial defects should be ruled out.
Cornea scrapings of any skin lesions may be sent to the laboratory for a Tzanck smear. However, this test will not differentiate between herpes simplex virus (HSV) and Varicella. Alternatively, cultures may be sent for immunofluorescence assays to look for IgM specific to VZV. Viral cultures and polymerase chain reaction testing may also be obtained to diagnose VZV.
Not many disease processes produce a painful vesicular rash. However, other conditions that create vesicular rashes should be considered especially in the absence of pain: for example, contact dermatitis and vaccinia dermatitis. Other disease entities that can mimic cornea findings include recurrent erosion, noninfectious cornea melts, infectious keratitis. There are numerous infectious and non-infectious entities that can exhibit ocular inflammation in the aqueous, vitreous, optic nerve, retina, and choroid.
High-dose oral acyclovir (800 mg five times a day), valacyclovir (1 g three times a day), or famciclovir (500 mg three times a day) for 7–10 days started within 72 hours after the appearance of the rash reduces the incidence of ocular complications but not of postherpetic neuralgia. Keratitis can be treated with a topical antiviral such as ganciclovir 0.15% gel.
Anterior uveitis requires treatment with topical corticosteroids and cycloplegics. Neurotrophic keratitis is an important cause of long-term morbidity. Varicella vaccination reduces the overall incidence but may trigger herpes zoster ophthalmicus
A varicella-zoster (shingles) vaccination is now recommended for patients over the age of 60. Although 90% of the population has prior exposure to VZV, there appears to be a benefit to booster immunity especially since the community incidence of native VZV exposure has decreased. During a recent study, a 50% decreased incidence of zoster and 66% reduction of postherpetic neuralgia was demonstrated