|Herpes Simplex Keratitis
Signs and Symptoms
A dendritic corneal ulcer is the hallmark sign of HSV infection, accompanied by stromal keratitis in more severe presentations. These ulcers may begin as nondescript punctate keratopathies, but quickly coalesce to form the familiar branching patterns which stain brightly with sodium fluorescein dye. Because the virus invades and compromises the epithelial cells surrounding the ulcer, the leading edges (the so-called "terminal end-bulbs") will stain with rose bengal or lissamine green.
After resolution, the virus remains dormant in the body of the host and can be reactivated in as many as 25 percent of cases by fever, trauma, stress, immunosuppressive agents or exposure to ultraviolet radiation. In recurrent attacks, the virus invades and replicates within the corneal epithelium. As the cells die, an ulcerative keratitis results. Disciform stromal scarring, conjunctivitis and uveitis are common sequelae.
Some practitioners recommend debriding the ulcer bed to remove active virus cells, but this has not been definitively proven to hasten resolution or improve the final visual outcome. You may also need to prescribe a cycloplegic (homatropine 2% t.i.d.-q.i.d. or scopolamine 0.25% b.i.d.-q.i.d.), again depending upon the severity of the uveitic response. Avoid topical steroids in cases of active epithelial HSV keratitis. Studies show that the virus replicates more rapidly in the presence of steroids, prolonging the course of the disease. The use of oral acyclovir (400mg 5x/day) or another oral antiviral for recalcitrant ulcers has yet to be proven clinically significant. However, it has been shown recently that the use of oral acyclovir 400mg q.d. significantly reduces the recurrence of herpes simplex keratitis in imunocompetent patients. At this point, consider using oral prophylaxis therapy only in patients with confirmed recurrent HSV keratitis or patients on initial presentation who request it after being thoroughly educated.
A new development in the management of herpes simplex keratitis has come in the form of topical acyclovir ointment (Zovirax). Place the ointment in the lower cul-de-sac five times per day at four hour intervals. At this point, toxicity seems to be low.
Other reports in this section
Eyelids & Eyelashes | Conjunctiva & Sclera | Cornea
Uvea | Vitreous & Retina | Optic Nerve & Brain | Oculosystemic Disease
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