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Herpes Simplex Keratitis
(Herpes Simplex Keratoconjunctivitis)
Herpes simplex keratitis is corneal infection with herpes simplex virus. It may involve the iris. Symptoms and signs include foreign body sensation, lacrimation, photophobia, and conjunctival hyperemia. Recurrences are common and may lead to corneal hypoesthesia, ulceration, and permanent scarring. Diagnosis is based on the characteristic dendritic corneal ulcer and sometimes viral culture. Treatment is with topical and occasionally systemic antiviral drugs.
Herpes simplex usually affects the corneal surface but sometimes involves the corneal stroma (the deeper layers of the cornea). Stromal involvement is probably an immunologic response to the virus.
As with all herpes simplex virus infections (see also Herpes Simplex Virus (HSV) Infections), there is a primary infection, followed by a latent phase, in which the virus goes into the nerve roots. Latent virus may reactivate, causing recurrent symptoms.
The initial (primary) infection is usually nonspecific self-limiting conjunctivitis, often in early childhood and usually without corneal involvement. If the cornea is involved, early symptoms include foreign body sensation, lacrimation, photophobia, and conjunctival hyperemia. Sometimes vesicular blepharitis (blisters on the eyelid) follows, symptoms worsen, vision blurs, and blisters break down and ulcerate, then resolve without scarring in about a week.
Recurrences usually take the form of epithelial keratitis (also called dendritic keratitis) with tearing, foreign body sensation, and a characteristic branching (dendritic or serpentine) lesion of the corneal epithelium with knoblike terminals that stain with fluorescein. Multiple recurrences may result in corneal hypoesthesia or anesthesia, ulceration, and permanent scarring.
Most patients with disciform keratitis, which involves the corneal endothelium primarily, have a history of epithelial keratitis. Disciform keratitis is a deeper, disc-shaped, localized area of secondary corneal edema and haze accompanied by anterior uveitis. This form may cause pain and vision loss.
Stromal keratitis can cause necrosis of the stroma and severe ache, photophobia, foreign body sensation, and decreased vision.
Most patients are managed by an ophthalmologist. If stromal or uveal involvement occurs, treatment is more involved and referral to an ophthalmologist is mandatory.
Topical therapy (eg, ganciclovir 0.15% gel applied q 3 h while awake [5 times/day] or trifluridine 1% drops q 2 h while awake [9 times/day]) is usually effective. Occasionally, acyclovir 400 mg po 5 times/day (or 3 times/day for recurrent herpes simplex keratitis) or valacyclovir1000 mg po bid is indicated. Immunocompromised patients may require IV antivirals (eg, acyclovir 5 mg/kg IV q 8 h for 7 days). If the epithelium surrounding the dendrite is loose and edematous, debridement by gentle swabbing with a cotton-tipped applicator before beginning drug therapy may speed healing.
Topical corticosteroids are contraindicated in epithelial keratitis but may be effective when used with an antiviral to manage later-stage stromal involvement (disciform or stromal keratitis) or uveitis. In such cases, patients may be given prednisolone acetate 1% instilled q 2 h initially, lengthening the interval to q 4 to 8 h as symptoms improve. Topical drugs to relieve photophobia include atropine 1% or scopolamine 0.25% tid.
Herpes simplex keratitis typically is a recurrence of primary herpes simplex eye infection that was typically a nonspecific, self-limiting conjunctivitis.
Characteristic findings include a branching dendritic or serpentine corneal lesion (indicating dendritic keratitis) or disc-shaped, localized corneal edema and haze plus anterior uveitis (indicating disciform keratitis).
Diagnosis is confirmed by finding a dendritic ulcer or by viral culture.
Treatment requires antivirals, usually topical ganciclovir or trifluridine or oral acyclovir or valacyclovir.
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