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Herpes simplex
keratitis is corneal infection with herpes simplex virus (see also Herpesviruses: Herpes Simplex Virus (HSV) Infections).
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 agents.
Herpes simplex usually affects the corneal surface but sometimes involves the deeper layers of the cornea (corneal stroma). Stromal involvement is probably an immunologic response to the virus.
As with all herpes simplex virus infections, there is a primary infection, following which the virus goes into a latent phase in the nerve roots. Latent virus may reactivate, causing recurrent symptoms.
Symptoms and Signs
Primary infection:
The initial (primary) infection is usually a nonspecific self-limiting conjunctivitis, often in early childhood and sometimes 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.
Recurrent infection:
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.
Stromal involvement:
Most patients with disciform keratitis, which involves the corneal stroma, have a history of epithelial keratitis. Disciform keratitis is a deeper, disk-shaped, localized area of 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 symptoms of severe ache, photophobia, foreign body sensation and decreased vision.
Diagnosis
Slit-lamp examination is mandatory. The slit-lamp finding of a dendrite is characteristic enough for the diagnosis in most cases. When the appearance is not conclusive, viral culture of the lesion can confirm the diagnosis.
Treatment
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, trifluridine 1% drops 9 times/day) is usually effective. Occasionally, acyclovir 400 mg po 5 times/day 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 drug 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.
Last full review/revision October 2008 by Melvin I. Roat, MD
Content last modified October 2008
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