Makindo Medical Notes

Related Subjects: |Episcleritis |Scleritis |Assessing a Red eye |Acute Angle Closure Glaucoma |Allergic and Infective Conjunctivitis |Anterior and Posterior Uveitis |Herpes simplex keratitis (HSK)

Exclude viral retinitis following pupil dilatation (especially in immunocompromised patients e.g. HIV, transplant) as this would warrant emergency (same day) referral

About

• HSK is a corneal infection with herpes simplex virus often with a central corneal ulcer
• Commonest form is epithelial keratitis, accounting for 50% to 80% of ocular herpes
• Less commonly Blepharoconjunctivitis, keratitis, iridocyclitis or acute retinal necrosis.

Aetiology

• Usually a Type 1 HSV infection due to reactivation
• Due to stress, sun exposure, fever, menstruation, medications
• Atopic patients will often have more severe disease.

Clinical

• Ask about cold sores and prior exposure.
• Ask about possible systemic immunosuppression
• Symptoms and signs include foreign body sensation
• Lacrimation, photophobia, and conjunctival hyperaemia.
• Typically unilateral, rarely bilateral, especially in severely atopic patients

Types

• Epithelial: Initially punctate lesions, coalescing into a dendriform pattern. dendritic ulcer, single or multiple. Associated with reduced corneal sensitivity. Enlargement can result in an 'amoebic' or 'geographic' ulcer (especially following inappropriate use of topical steroids)
• Stromal: Necrotic stroma, stromal infiltrates, vascularisation, scarring, keratic precipitates, and in the anterior chamber, uveitis, possibly raised intraocular pressure
• Disciform keratitis: Central or eccentric zone of epithelial oedema overlying an area of stromal thickening. Folds in Descemet's membrane, uveitis and keratic precipitates
• Metaherpetic ulcer (trophic keratitis) : Due to a combination of denervation, drug toxicity, persistent defects in epithelial basement membrane

Use fluorescein to ascertain the nature of any epithelial defect. Check for dendritic ulcer/s, which are usually unilateral. Multiple previous episodes may have also led to cornea stromal scarring and decreased vision. A dendritic ulcer (affecting the corneal epithelium) may also be complicated by inflammation of the deeper corneal layers, which, if left untreated, can sometimes lead to perforation. Look for corneal opacification, loss of iris detail through a cloudy cornea and reduced vision

Investigations

• Isolation and characterisation of virus from corneal swab or biopsy

Differentials

• Herpes zoster keratitis
• Bacterial, fungal or amoebic keratitis

Management: Topical steroids alone make it worse so avoid

• Treat with topical Aciclovir. Avoid topical steroid. Refer to an ophthalmologist within 1–2 days.
• Acute Herpes Simplex: in non-contact lens wearing adults and where HSK is confined to the epithelium, commence antiviral therapy with one of the following: oc. Aciclovir 3%, e.g. Zovirax, ophthalmic preparation, 5x daily ganciclovir 0.15% ophthalmic gel (Virgan), 5x daily. Have a low threshold for referral for this condition
• Recurrent Herpes Simplex: where there is: a clear history of previous attacks no doubt about the diagnosis and only epithelial involvement commence antiviral therapy (as above). With recurrence, the disease may extend into the corneal stroma and cause a red-eye, ocular discomfort, blurred vision, and corneal scarring. The treatment of stromal involvement is multifactorial and may not be successful. Corneal transplantation may be needed.
• Acute or recurrent epithelial HSK with no stromal involvement: alleviation or palliation; but refer urgently (within one week) to an ophthalmologist if epithelium has not healed after seven days
• If stroma involved, or in children or contact lens wearers, or in bilateral cases): emergency (same day) referral to an ophthalmologist
• Severe cases: Antivirals (e.g. (e.g., ganciclovir 0.15% ophthalmic gel five times daily for at least 1 week or until healed) and/or systemic) + /-Topical steroid
• Surgical debridement. Penetrating keratoplasty in some quiescent cases with scarring

Advice

• Avoid touching eyes if you have a cold sore/blister
• Do not use steroid eye drops unless you are taking an anti-viral medicine
• Stop wearing contact lenses if you keep getting infections.

Complications

• Complications include uveitis, keratitis, and glaucoma

References

• HSV Keratitis

Revisions