Background <p>Acute retinal necrosis triggered by routine cataract surgery is a rare condition, which may be overlooked by the clinicians. We report a case of unilateral acute retinal necrosis (ARN) with the onset 4 days after uncomplicated cataract surgery. The patient demonstrates satisfactory outcomes following anti-virus therapy.</p> Case presentation <p>A 73-year-old male presenting with 1-day history of floaters, eye redness, pain and vision loss in his right eye was referred to our clinic. He had just completed uncomplicated phacoemulsification and posterior chamber intraocular lens implantation in the right eye 5 days ago. He had a history of cutaneous herpes zoster infection at the age of 40. The visual acuity was counting fingers in the right eye at presentation with marked anterior and posterior segment inflammation. ARN was suspected based on fundus findings, including retinal hemorrhage, vessel attenuation and retinal whitening. Following anti-virus therapy, the inflammation and visual acuity improved. Aqueous humor for viral DNA testing using polymerase chain reaction showed positivity to varicella zoster virus (VZV), confirming the diagnosis of VZV associated ARN. The visual acuity improved to 18/20 at one month follow-up examination with no recurrence of inflammation.</p> Conclusions <p>Clinicians should be aware of the possibility of cataract surgery as a triggering event for reactivation of VZV and subsequent ARN. Anti-virus therapy initiated at early phase of the disease may yield satisfactory visual outcomes for the patient. Careful preoperative screening and postoperative monitoring in patients with a history of herpes infection is important.</p>