Background:Herpes virus is considered to be the pathogen of acute retinal necrosis (ARN) infection.Previous studies have found that patients with ARN caused by the varicella-zoster virus (VZV) are often older,and patients with herpes simplex virus (HSV) induced ARN are considerably younger.However,in our clinical work,we find that VZV is also a pathogen in younger ARN patients.We,therefore,aimed to analyze the common etiology of younger ARN patients.Methods:A retrospective analysis was made of 20 eyes (18 patients) diagnosed as having ARN in the Department of Ophthalmology of Peking Union Medical College Hospital from 2014 to 2016.All patients were reviewed for demographic data,clinical course,clinical manifestations,time from onset to initial physician visit,duration of follow-up,visual acuity at both presentation and final visit,and treatment strategies.A paired t test was used to compare visual acuity between the presenting vision and those of final follow-up.Vitreous or aqueous specimens from 18 eyes of 18 patients were analyzed with multiplex polymerase chain reaction (mPCR)/quantitative PCR (qPCR) and xTAG-liquid chip technology (xTAG-LCT) to determine the causative virus of ARN.Results:Final best visual acuity (BCVA) improved significantly from 1.36±0.95 (median 20/400) to 0.95 ± 0.82 (median 20/100) (t =2.714,P =0.015) after systemic and intravitreal antiviral treatment combined with or without pars plana vitrectomy.PCR and xTAG-LCT results showed four of the five samples in the younger group (32.2 ± 5.2 years) and 12 of the 13 samples in the senior group (53.6 ±4.9 years) were positive for VZV,and two of the five samples in the younger group were positive for HSV-1.Conclusions:This study demonstrates that VZV is also a common causative virus for ARN in younger patients.Considering this finding,a systemic antiviral treatment protocol should be immediately changed to intravenous ganciclovir when the patient does not respond to acyclovir before determining the causative virus,especially in younger patients.