Two laboratory methods for diagnosis of herpes simplex keratitis

Rapid diagnosis of herpetic keratitis using direct immunoperoxidase technique

The direct immunoperoxidase technique was tested for diagnosis of herpetic keratitis. The technique was performed on corneal epithelial specimens from 28 herpetic keratitis cases and 12 controls. Ulcers were stained with rose bengal or fluorescein and examined at the slit-lamp biomicroscope to differentiate between herpetic and nonherpetic etiology. Scrapings obtained from the corneal epithelial ulcers were stained with direct immunoperoxidase technique. The whole procedure, including staining and examination of the slides, took a total of 70 min. The test proved to be accurate, easy to perform and to interpret, rapid and relatively inexpensive with a sensitivity of 93%, and a specificity of 100%.

Immunofluorescent staining and corneal sensitivity in patients suspected of having herpes simplex keratitis

We examined immunofluorescent staining and corneal sensitivity in 25 control subjects (25 eyes) with normal corneas, six patients (eight eyes) with possible herpes simplex keratitis, and 44 patients (48 eyes) with corneal lesions (recurrent erosion, superficial punctate keratitis, marginal ulcer, and follicular keratoconjunctivitis) in whom herpes simplex keratitis was not suspected. On immunofluorescent staining, all 25 control subjects had negative reactions, all eight eyes suspected of having herpes simplex keratitis had positive reactions, and 11 (23%) of the 48 eyes not suspected of having herpes simplex keratitis had positive reactions; the remaining 37 eyes had negative reactions. Of the 11 eyes not suspected of having herpes simplex keratitis but that had positive reactions on immunofluorescent staining, nine had recurrent erosions and the remaining two eyes had superficial punctate keratitis. Of the eight eyes with possible herpes simplex keratitis, seven (88%) had decreased corneal sensitivity. Of the 11 eyes not suspected of having herpes simplex keratitis but that had positive reactions on immunofluorescent staining, eight (73%) had decreased corneal sensitivity. Of the 37 eyes not suspected of having herpes simplex keratitis that had negative reactions on immunofluorescent staining, 11 (30%) had decreased corneal sensitivity.