Viral corneal infections, while not overwhelmingly common, can be puzzling and even sight-threatening. This member of the Herpesviridae family, herpes simplex virus (HSV-1) or human herpes virus 1 (HHV-1) remains the leading cause of herpetic ocular incidents, causing nearly 95 percent of total infections.1 The sequelae of ocular manifestations potentially include long-term deep vascularization, significant corneal scarring, and disqualification from contact lens use. For best treatment outlook, emphasis should be placed on early detection, accurate diagnosis, and vigilant treatment. This article serves to summarize HSV corneal infections, subsequent diagnostic review, and discuss current treatment algorithms.
Herpes simplex virus, from a systemic standpoint, is very common in the population—with nearly 90 percent of the population testing positive for carrying the latent virus. Looking at it by age, roughly 20 percent of the population over the age of 20, and nearly 100 percent over the age of 60, will have contracted it.2 Though such a high number of adults have been exposed, a very low percentage of individuals develop clinically recognized ocular disease. The prevalence has been estimated at 5 to 20 cases per 10,000 individuals per year.2 These rare occurrences are overwhelmingly a unilateral disease; bilateral cases tend to be more severe and usually occur in younger adults.
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Primary HSV infection via contact with infected fluids may incubate for up to a month and will usually present as some variation of oropharyngitis. After this initial infection, the virus enters a latency stage, which may last from months to years, in the trigeminal ganglion. This location of latency allows the virus to activate anywhere along the trigeminal nerve, including the ophthalmic division. Such a reactivation of the disease, typically the first ophthalmic presentation, is termed the primary ocular infection. The inciting factor is usually some insult to the patient’s immune system (stress, injury, illness) and may be as simple as wearing contact lenses, spending a day in direct sunlight, enduring an afternoon of chilling wind, or feeling the stress of finding a new job.