Digital droplet polymerase chain reaction analysis of common viruses in the aqueous humour of patients with Posner-Schlossman syndrome in Chinese population

Background To compare the detection results consistency of quantitative polymerase chain reaction (qPCR) and digital droplet polymerase chain reaction (ddPCR), and determine the value of ddPCR for viral detection in the aqueous humour. Methods A total of 130 aqueous humour samples were collected, including 60 patients with Posner-Schlossman syndrome (PSS) in case group and 70 elderly patients with senile cataract in control group. The target nucleic acid fragments of human cytomegalovirus (HCMV), herpes simplex virus, Epstein-Barr virus and varicella zoster virus in aqueous humour were analysed by qPCR and ddPCR, respectively, for the diagnosis and curative effect monitoring of pathogen-induced PSS. Samples with inconsistent results were verified by next-generation sequencing. Results There were 27 and 20 HCMV-positive cases detected in the case group by ddPCR and qPCR, respectively. ddPCR increased the sensitivity for the HCMV virus detection from 400 to 100 copies/mL. No other pathogens were found in this study. The results of ddPCR were consistent with that of next generation sequencing. The mean (SD) of Lg (HCMV copies/mL) detected by ddPCR and qPCR were 1.66 (1.92) and 1.10 (1.61), respectively (P < 0.001). Compared with qPCR, results of ddPCR showed better consistency with validity of clinical treatment. All patients with ddPCR-positive results had good validity on antiviral therapy, exhibiting anterior chamber inflammation remission, resolution of corneal oedema and good IOP control within 1 month. Conclusions HCMV was the leading cause of pathogen-induced PSS in the Chinese population. ddPCR was a promising tool for early detection, accurate diagnosis and therapeutic validity monitoring of pathogen-induced PSS. The high sensitivity of ddPCR could avoid repeated anterior chamber tap.