Quantitative Analysis of Herpes Simplex Virus Genome in Tears from Patients with Herpetic Keratitis

Purpose Herpetic keratitis is manifested in various corneal disorders, for example, dendritic keratitis, persistent epithelial defect, disciform keratitis, and endotheliitis. In this paper, we report on the quantity of herpes simplex virus (HSV) genome in tears from patients with various types of herpetic keratitis in an attempt to understand the role of HSV in these conditions. Methods We collected tear samples from both eyes of 56 consecutive patients with herpetic keratitis who visited Kinki University Hospital between June 2000 and May 2002. All patients had unilateral herpetic keratitis: epithelial keratitis in 27 eyes; persistent epithelial defect in 6; active disciform stromal keratitis in 14; silent stromal keratitis in 6; and endotheliitis in 3. We measured levels of HSV genome in these tear samples using a real-time polymerase chain reaction (PCR) method. Results In epithelial keratitis, HSV DNA was detected in all 27 samples from affected eyes (6.4 ± 4.4 × 105copies/sample). In persistent epithelial defect, HSV DNA was detected in all 6 samples from affected eyes (8.5 ± 3.3 × 104copies/sample). In active disciform stromal keratitis, HSV DNA was detected in 8 of the 14 affected eyes (1.4 ± 1.1 × 105copies/sample including zero values in negative samples). HSV DNA was not detected in samples from unaffected eyes or eyes affected by silent stromal keratitis or endotheliitis. Conclusion Real-time PCR is a useful method for quantifying HSV DNA in tear samples from patients with herpetic keratitis. Using this method, we demonstrate that HSV reproduction occurs in persistent epithelial defect and disciform stromal keratitis.