Acute retinal necrosis syndrome (ARN syndrome) is a rare, rapidly progressive viral retinitis with a grim functional prognosis. We present a case of a 43-year-old immunocompetent woman who experienced unilateral acute retinal necrosis, with Varicella-Zoster Virus (VZV) infection as the etiology. A unilateral vesicular facial rash accompanied by rapidly declining visual acuity over 7 days prompted consultation. Intravenous antiviral treatment and panretinal photocoagulation laser (PPR) were initiated, followed by antiviral prophylaxis. The patient developed ophthalmic zona lesions, peripheral retinal ischemia, and unilateral macular serous retinal detachment (SRD). Treatment included valacyclovir, corticotherapy and PPR laser. Knowledge of this condition, diagnosed clinically, is crucial due to its rapid progression and severe complications. Early intervention appears to be a significant prognostic factor, emphasizing its therapeutic urgency.