Herpes Simplex Acute Retinal Necrosis Presenting as Unilateral Disc Swelling in Young Immunocompetent Patients.

Purpose: To report two cases of young immunocompetent males with herpes simplex acute retinal necrosis (HSV ARN) with initial diagnosis of unilateral disc swelling.
Methods: Retrospective case series.
Results: Two young immunocompetent males who were diagnosed to have unilateral disc swelling were treated as presumed optic neuritis and started on systemic steroids. On dilated fundal examination, unilateral retinitis and vasculitis was found after 2-3 days of systemic steroids and the diagnosis of ARN was made. Tetraplex vitreous tap subsequently returned as HSV-2 and HSV for the first and second patient, respectively. Both patients had no significant systemic medical history and tested negative for human immunodeficiency virus (HIV). Despite aggressive treatment, both patients developed profound visual morbidity.
Conclusions: Close monitoring of patients with unilateral disc swelling and dilated fundus evaluation is critical, particularly upon initiation of systemic steroid therapy, even if immunocompetent, as misdiagnoses can result in potentially devastating consequences.