Impression Cytology of Herpetic Simplex Keratitis in Rabbits

PURPOSE: To use impression cytology to examine the structural changes in corneal epithelial cells infected with the herpes simplex virus in rabbit eyes. METHODS: Corneal surfaces of 7 rabbits were scratched using a 25-gauge needle. Herpes simplex virus (type 1, Kos strain) was inoculated to the injured cornea. As the corneal diseases were observed using slit lamp biomicroscopy, impression cytology was performed for 18 days after inoculation. Specimens were stained with hematoxylin-eosin and examined using optical microscopy. RESULTS: Corneal lesions consisted mainly of round epithelial cells, inflammatory cells, ballooning cells, multinucleated giant cells, and various inclusion bodies. Over time, the corneal epithelial cells peeled away as a result of corneal edema in the corneal lesions. Dendritic lesions were also observed. In the recovery phase, the number of detached cells and infiltrated inflammatory cells decreased. CONCLUSIONS: It was presumed that dendritic lesions might have been formed at the scratched cornea region, thereby aggravating the epithelial cells falling off as a result of the infiltration of inflammatory cells. These cytopathologic effects occur in experimental herpes simplex keratitis.

Clinical pattern of recurrent herpes simplex keratitis.

PURPOSE: To document the clinical pattern in recurrent herpes simplex disease. METHODS: Eyes with clinically documented pattern of corneal manifestation on more than one occasion were analysed. For each eye recruited, the clinical pattern of the disease at each recurrence of herpes simplex corneal disease, age, disease-free intervals, triggering factors, laterality and steroid abuse were noted and evaluated. RESULTS: For an average follow up of 6.9 years, a recurrence rate of 0.6 episodes per year was observed. Disease-free intervals of 75.7 months for epithelial herpes simplex disease was considerably longer than the 21.3 months observed for stromal disease. Clinical pattern of recurrence was of the same type following first episode of disciform keratitis, epithelial keratitis and endothelitis in 84%, 72.7%, and 75% of the eyes respectively. CONCLUSION: Herpes simplex disease often recurs in the same manifest clinical pattern as the first episode. This clinical evidence provides additional support for the potential role of herpes simplex biotypes in determining manifestation of clinical disease pattern.