HSV KERATITIS

Berthold Seitz MD

While herpes simplex virus (HSV) remains a very frequent cause of unilateral keratitis in adults and bilateral keratitis in children, the prognosis is usually quite good given that the various forms of appearance are known and provided that the therapeutic regimens, both medical and surgical, are adequately chosen, according to Berthold Seitz MD.

“Herpetic keratitis is a chameleon. However, given adequate medical and microsurgical management it has lost much of its horror today,” Prof Seitz told delegates attending the 2015 Congress of the European Society of Ophthalmology (SOE) in Vienna, Austria.

In a broad overview of HSV-related ocular infections, Prof Seitz said that the classification of herpes simplex keratitis has evolved in recent years and now includes distinct forms such as infectious epithelial keratitis (dendritic or geographic keratitis), neurotrophic keratopathy, stromal keratitis (necrotizing and non-necrotizing), and endotheliitis.

The most well-known herpetic infection and the most common is infectious epithelial keratitis, said Prof Seitz. It may take the form of dendritic keratitis with branching linear lesions that typically break through the basal membrane of the cornea, with terminal enlargements, and swollen epithelial margins with living virus. If the dendrites become confluent, it may evolve into geographic keratitis.

It is also important to distinguish infectious epithelial keratitis from acanthamoeba keratitis, a rare opportunistic infection that presents with similar non-specific symptoms as bacterial and viral keratitis.

“We did a survey in Germany, and saw that over the last 20 years more than 50 per cent of acanthamoeba keratitis cases were misdiagnosed as epithelial herpetic keratitis. To make this differential diagnosis, confocal microscopy, histopathology and especially polymerase chain reaction (PCR) tests are indispensable,” he said.

Infectious epithelial keratitis is typically treated with topical trifluorothymidine or acyclovir/ganciclovir, no steroids and epithelial abrasion if a surgical option is required.

Neurotrophic keratopathy, often referred to as meta-herpetic keratitis, is a late stage, burned out herpetic keratitis, said Prof Seitz, with no immune reaction, no infection, reduced corneal innervation and diminished tear secretion. It is treated with non-preserved artificial tears, hyaluronic acid gels and autologous serum. Surgical approaches include amniotic membrane transplantation (AMT), botulinum toxin application in the upper lid for temporary iatrogenic ptosis, or
temporary tarsorrhaphy.

THERAPEUTIC STEP APPROACH

Necrotizing stromal keratitis, or the classic herpetic ulcer, typically presents with a lot of active HSV in the stroma, initially without hypopyon, and corneal neovascularisation is also frequently present. Therapy is topical antivirals, antibiotics and cycloplegics and initially no steroids, said Prof Seitz. Systemic antiviral treatment is also recommended, while AMT and emergency keratoplasty are surgical options.

“I propose a therapeutic step approach using appropriate topical and systemic antibiotics, AMT, elective keratoplasty in the quiet interval, while reserving emergency keratoplasty only in the case of perforation,” he said.

Non-necrotizing stromal keratitis, or interstitial keratitis, is treated with topical and systemic acyclovir and steroids, which are tapered over a few weeks or even months, said Prof Seitz, Department of Ophthalmology at the Saarland University Medical Centre in Homburg, Saarland, Germany.

For endotheliitis, topical treatment is with acyclovir, steroids and anti-glaucoma medication to treat associated ocular hypertension but no prostaglandin analogues. Systemic treatment is oral acyclovir, steroids and potentially anti-glaucoma drugs such as Diamox.

On the question of penetrating keratoplasty (PKP), recent research has shown that graft to host transmission of HSV seems to be a real phenomenon, said Prof Seitz, with potential major negative impact on graft survival. “To enable an appropriate prophylactic acyclovir treatment in distinct cases after PKP we advocate the screening of both patient and donor corneas for HSV-1 by use of PCR testing. We also need to be aware that resistance of acyclovir may occur during long-term prophylaxis in immunocompromised patients,” he added.

Berthold Seitz: Berthold.seitz@uks.eu