Can Xalatan Reactivate the Herpes Simplex Virus?
Christopher J. Quinn, O.D.
What’s the connection between a herpes simplex virus in the eye and
the prostaglandin latanoprost (Xalatan)? It may be one you didn’t expect.
In fact, latanoprost may be linked to reactivation of the herpes virus.
Recurrence of primary herpes simplex virus in the eye usually manifests
as epithelial dendritic keratitis. Following the primary infection with
the herpes virus, the virus remains dormant in the trigeminal ganglion
layer until some precipitating event causes it to reactivate. The virus
then migrates along the ophthalmic division of the fifth cranial nerve
and begins active replication in the corneal epithelium.
Exactly what stimulates the herpes virus to reactivate has been difficult
to prove. Reactivating factors may include trauma, surgery, infections,
exposure to sunlight, fever, emotional stress and menstruation. Each of
these conditions causes some degree of increase in inflammatory action,
so we must ask the question: Are inflammatory mediators involved in stimulating
recurrence of latent virus?
Prostaglandins are common inflammatory mediators that have a variety
of physiological effects. Various tissues and inflammatory cells produce
and release these mediators. At least one report describes reactivation
of herpes keratitis in patients who are taking latanoprost for glaucoma
management. 1
The report is based on three cases in which herpes simplex keratitis
developed after initiation of latanoprost therapy. Two of the patients
had a history of herpes epithelial keratiti
The herpes resolved in the patients once they discontinued the latanoprost
and switched to topical trifluridine (Viroptic). In two cases, the herpes
recurred when they restarted the latanoprost. One additional study showed
that, at least in an animal model, severity of herpes epithelial keratitis
increased in eyes treated with latanoprost vs. control eyes.2
What does this information mean to us in terms of clinical use? Neither
report establishes a causal relationship between latanoprost use and an
increased frequency of herpes epithelial keratitis. We know topical medications
can cause epitheliopathy and pseudodentritic keratitis, which may have
been the case in any of the patients the first study described.
We also know that herpes epithelial keratitis has a pattern of recurrence
in patients who are not using topical latanoprost.
If you carefully evaluate any suspected dendrites, and can identify
the classical terminal end bulbs seen in herpes infection, you should be
able to reach an accurate diagnosis. If you have a patient on latano-prost,
and he or she develops herpes epithelial keratitis, it may be best to discontinue
the latanoprost until the keratitis resolves.
If you choose to restart the latanoprost once the symptoms resolve,
carefully monitor the patient for any signs of recurrent infection. You
may even want to consider using other agents to lower intraocular pressure
in patients with a history of herpes epithelial keratitis.
In the meantime, we hope that further study will give us more information
about the factors that influence the recurrence of herpes epithelial keratitis.
1. Wand M, Gilbert CM, Liesegang TJ. Latanoprost and Herpes Simplex
Keratitis. Am J Ophthalmol May 1999;127:602-604.
2. Kaufman HE, Varnell ED, Thompson HW. Latanoprost increases the severity
and recurrence of herpetic keratitis in the rabbit. Am J Ophthalmol 1999;127:531-536.
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