Herpes simplex and stromal keratitis

Pertinent questions when taking the history

• When did the symptoms begin?
• Have any treatments been tried? Did they improve the vision or the discomfort?
• Is there a history of recurrent eye inflammation or infection?
• Is there any history of HSV, or of unusual lesions or ulcers? If so, how often do recurrences occur?
• Is the patient immunosuppressed?
• Does the patient wear contact lenses? Lenses should be removed, and a microbial infection should be considered in any contact lens wearer.

Visual vital signs

Vision, pressure, and pupils, recorded and handed off like any other vital sign. Here they help separate surface disease from the deeper stromal and intraocular inflammation that costs vision.

Describe the focused anatomy

Two different diseases share this name. HSV keratitis is viral infection of the corneal surface, the epithelium. Stromal keratitis is an inflammatory reaction to viral particles in the thick middle layer of the cornea, which swells and turns hazy, and it causes the greater loss of vision.

• Eyelids and skinAre there ulcerations or vesicles on the lids?
• ConjunctivaIs the affected eye injected?
• Cornea, epithelial diseaseAre there raised, classic branching dendrites on the corneal epithelium after fluorescein? Are there white infiltrates associated with the dendrites? Recurrent disease can look atypical, with scattered or irregular dendrites.
• Cornea, stromal diseaseIs there a white or gray haze in the stroma, or a swollen, cloudy cornea? Stromal and endothelial HSV often present without dendrites, and more often in a patient who has had herpetic eye episodes before. If the diagnosis is uncertain or a microbial infection is possible, arrange ophthalmology the same or next day. Suspicion for infection is higher after recent trauma and in contact lens wearers.
• Anterior chamberIs it clear, or hazy with inflammatory debris? A hazy chamber may indicate iritis, which left untreated can lead to long term pupil abnormalities or cataract. Arrange ophthalmology within one day.
• PupilDoes the pupil move, or does it appear static from synechiae, where inflammatory debris sticks the iris to the lens? For pain from iritis, one drop of a short acting cycloplegic such as cyclopentolate 1% is reasonable if the anterior chamber is not shallow. Leave atropine, which lasts up to two weeks, and any attempt to break synechiae to ophthalmology.

Supporting imaging, if needed

• Usually noneHSV keratitis and HSV stromal keratitis are clinical diagnoses. Imaging is not usually required.
• CT orbitsConsider if orbital signs or symptoms are present, such as an afferent pupillary defect, proptosis, restricted eye movements, or double vision, to rule out more diffuse disease.

Treatment

HSV keratitis

• Oral antiviral, dendritic ulcerAcyclovir 400 mg three to five times daily, valacyclovir 500 mg twice daily, or famciclovir 250 mg twice daily, for 7 to 10 days.
• Oral antiviral, larger geographic ulcerAcyclovir 800 mg five times daily, valacyclovir 1 g three times daily, or famciclovir 500 mg twice daily, for 14 to 21 days. Adjust every oral dose for renal function.
• Topical antiviralGanciclovir 0.15% ophthalmic gel (Zirgan), one drop five times daily to the affected eye until the ulcer heals, then three times daily for 7 more days. One correctly dosed oral or topical agent is enough.

Stromal keratitis

• Start the oral antiviral nowIf stromal keratitis is suspected, begin oral antiviral therapy at the point of care and arrange next day ophthalmology follow up for focused treatment recommendations.
• Steroid drops wait for ophthalmologyStromal keratitis is treated with steroid drops together with an oral antiviral, usually for ten weeks or longer. Ophthalmology should start and taper the steroid after ruling out active epithelial infection at the slit lamp. A short delay for that visit does not worsen final vision.

Recurrent HSV

• Treat the episodeA similar strategy to the first infection.
• Topical corticosteroidUsed to treat stromal corneal inflammation and uveitis, the inflammation of the middle layers of the eye. Do not start unless the diagnosis is certain and ophthalmology is actively monitoring the condition.
• Prophylaxis, decided by ophthalmologyAcyclovir 400 mg twice daily, valacyclovir 500 mg once daily, or famciclovir 250 mg twice daily, usually for at least a year, to reduce the frequency of recurrences. Higher doses are used in special cases such as after corneal transplant.

Follow up

• IntervalOphthalmology follow up one to two days after the oral antiviral is started, to assess response.
• SoonerEncourage more urgent follow up if stromal keratitis is present, the diagnosis is uncertain, or a topical corticosteroid is being considered. Make sure the oral antiviral is started at the initial point of care.
• Contact lensesAvoid while the condition is being treated.
• Protect othersHSV spreads through direct contact with eye secretions, saliva, or open lesions. Until any lid or lip lesions have crusted, the patient should wash hands often, avoid touching the eye, not share towels, and avoid kissing or close face to face contact with newborns and with people who have eczema, burns, or weakened immune systems. There is no vaccine for herpes simplex.
• RecurrenceRecurrence is common in both HSV keratitis and stromal keratitis. Therapy to prevent recurrence should be discussed at outpatient ophthalmology follow up. Emphasize adherence to the treatment regimen and recognition of early symptoms.