Detection of herpes simplex virus DNA in atypical epithelial keratitis using polymerase chain reaction

Abstract

Aim: To study herpes simplex virus (HSV) DNA in tears from patients with atypical epithelial keratitis of unknown aetiology.

Methods: Tear samples were collected from 17 affected eyes of 17 consecutive patients suffering from epithelial keratitis in whom HSV keratitis was suspected but whose diagnosis was difficult on the basis of clinical manifestations alone. Using reduced sensitivity polymerase chain reaction (PCR), tear samples were tested for HSV DNA. Tears from the unaffected eyes of the 17 patients were also examined, along with 38 tear samples from 19 normal volunteers. Southern blot analysis was performed to confirm that amplified DNA bands were specific for HSV. Clinical correlation with photographs of corneal lesions was also investigated.

Results: HSV DNA was detected in tears from the affected eyes of eight of the 17 patients with suspected HSV keratitis. Tears from the affected eyes of the other patients were PCR negative, as were tears from the unaffected eyes of all 17 patients, and from the 38 normal eyes. There was no correlation between PCR results and clinical manifestation of keratitis.

Conclusions: Based on the sensitivity of the PCR system, eight of 17 suspected HSV keratitis patients were confirmed as suffering from HSV keratitis. HSV keratitis should therefore be considered as a possible diagnosis in atypical epithelial keratitis.

Figure 1

Fluorescein stained anterior segment photographs of 17 patients with atypical epithelial keratitis. Photograph numbers match patient numbers.

Figure 2

Detection of herpes simplex virus DNA in tear samples. (Top) Agarose gel electrophoresis of PCR products. Lanes 1-17 represent tears from 17 eyes of atypical epithelial keratitis patients. P=positive control; N=negative control. Patient Nos 3, 5, 6, 7, 8, 10, 11, 17 showed 142 bp amplified bands. (Bottom) Southern blot hybridisation confirms results of agarose gel electrophoresis. Lanes 1-P are same as those at the top.

Figure 3

Distribution of percentages of 14 ophthalmologists suspecting herpetic keratitis in PCR positive and negative patients. Each lozenge matches one patient.