Treatment of Refractory Acute Retinal Necrosis with Intravenous Foscarnet or Cidofovir

Purpose: To report use of intravenous foscarnet or cidofovir for the treatment of refractory acute retinal necrosis (ARN).Methods: Retrospective chart review.Results: Four immunocompetent men aged 45-90 years presented with ARN from 2008-2014. One patient with two prior episodes of herpes simplex virus (HSV) ARN developed ARN after 6 years of antiviral prophylaxis. His condition worsened on acyclovir followed by intravenous foscarnet but responded to intravenous cidofovir (final VA in involved eye 20/20). Another patient with HSV ARN had received prolonged acyclovir prophylaxis for HSV keratitis; ARN improved after switching from acyclovir to intravenous foscarnet (final VA 20/125). Two patients with varicella zoster virus (VZV) ARN initially responded to acyclovir but developed fellow eye involvement 2-8 weeks later that worsened on acyclovir but responded to intravenous foscarnet (fellow eye final VA 20/20, 20/40).Conclusions: Cases of HSV or VZV ARN that worsen despite intravenous acyclovir treatment may respond to intravenous foscarnet or cidofovir.