Polymerase chain reaction test for diagnosis of infectious uveitis

BackgroundTo study the clinical utility of broad-range real-time Polymerase Chain Reaction (PCR) assay in patients suspected for infectious uveitis and to analyze the clinical relevance.MethodsMedical records of patients with uveitis were assessed in whom PCR analysis of intraocular fluids was performed between January 2018 and February 2021. Intraocular samples were investigated for cytomegalovirus (CMV), Epstein-Barr virus (EBV), varicella zoster virus (VZV), herpes simplex viruses type 1 and 2 (HSV1,2), human T-lymphotropic virus type 1 (HTLV-1), Toxoplasma gondii and also for bacterial 16 S and fungal 18 S/28S ribosomal DNA (rDNA).ResultsAqueous paracentesis and vitreous sampling was done for 151 (81.2%) and 35 (18.8%) patients, respectively. Most of the patients had panuveitis (61.3%). PCR results were positive in 69 out of 186 patients (37%) according to the following order: CMV (18 cases), VZV (18 cases), fungal 18s/28s rDNA (17 cases), HSV (9 cases), bacterial 16s rDNA (3 cases), HTLV-1 (2 cases), and Toxoplasma gondii (2 cases). PCR positivity rate was 5.8% in patients with undifferentiated panuveitis. EBV was not detected at all. Initial treatment was changed in 38 patients (20%) based on PCR results. The overall sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of PCR test for aqueous samples was 82%, 91%, 96%, and 87%, respectively. No significant adverse effect related to sampling was reported.ConclusionPCR analysis of intraocular fluids in patients with suspected infectious uveitis plays an important role in confirming diagnosis or changing treatment with good predictive value. However, routine PCR test in patients with undifferentiated panuveitis in order to rule out possible underlying infectious etiology had low benefit. Key message of the ArticleWhat is already known on this topic:PCR analysis of intraocular fluids in patients with suspected infectious uveitis is a useful adjunct method.What this study adds:PCR test has low clinical utility in patients with undifferentiated panuveitis and low suspicion for infectious etiology. Multicenter studies is needed for better judgment.How this study might affect research, practice or policy:These findings suggest that developing an algorithm with clear indications for considering PCR analysis in patients with uveitis may improve its diagnostic value.