Acute retinal necrosis following dexamethasone intravitreal implant (Ozurdex®) administration in an immunocompetent adult with a history of HSV encephalitis: a case report

Background: Dexamethasone intravitreal implants (0.7 mg) (Ozurdex®, Allergan Inc., Madison, NJ) are FDA approved for managing macular oedema (ME) of retinal vein occlusion (RVO). The major complications associated with intravitreal Ozurdex® implant include increased intraocular pressure and cataract progression. In regard to the occurrence of retinal complications, we report an unusual intravitreal Ozurdex® implantation-related acute retinal necrosis (ARN).

Case presentation: A 45-year-old immunocompetent woman with a history of encephalitis presented with photophobia, redness, floaters, and rapidly decreased vision in her left eye. Three and six months ago, she received two doses of intravitreal Ozurdex® implant for ME of RVO. Clinical evaluation, including slit-lamp biomicroscopy, retinal photography, and fluorescein angiography, revealed anterior chamber cells, granulomatous keratic precipitates, cells in the vitreous, optic disc oedema, occlusive retinal vasculitis, scattered retinal haemorrhages, one quadrant of peripheral white areas with retinal necrosis, optic disc and vessels fluorescein staining, and retinal nonperfusion zones. All the above clinical manifestations showed an ARN. Herpes simplex virus was detected in the aqueous and vitreous humour by quantitative polymerase chain reaction testing. Intravenous acyclovir 500 mg tid for 7 days followed by oral valcyclovir was immediately performed for ARN. At 4 months, the patient's condition improved without retinal detachment, and the best-corrected visual acuity remained stable at 0.3.

Conclusions: ARN might represent a risk of Ozurdex® administration.

Keywords: Acute retinal necrosis; Dexamethasone intravitreal implant; Intravitreal injections; Retinal vein occlusion.