Acute Retinal Necrosis in the United Kingdom

Acute Retinal Necrosis in the United Kingdom: Results of a Prospective Surveillance Study

Abstract and Introduction

Abstract

Background. To determine the incidence of acute retinal necrosis (ARN) in the United Kingdom and to describe the demographics, management, and visual outcome in these patients.
Methods. This was a prospective study carried out by the British Ophthalmological Surveillance Unit (BOSU) between September 2007 and October 2008. Initial and 6-month questionnaires were sent to UK ophthalmologists who reported cases of ARN via the monthly BOSU report card system.
Results. In all, 45 confirmed cases (52 eyes) of ARN were reported in the 14-month study period, giving a minimum incidence of 0.63 cases per million population per year. There were 20 females and 25 males. Age ranged from 10 to 94 years. Eight patients had a history of herpetic CNS disease. Aqueous sampling was carried out in 13 patients, vitreous in 27, and cerebrospinal fluid (CSF) in 4. Varicella-zoster virus followed by herpes simplex were the most common causative agents. Treatment in 76% of the cases was with intravenous antivirals; however, 24% received only oral antivirals. In all, 47% of patients had intravitreal antiviral therapy. Visual outcome at 6 months was <6/60 in 48% of the affected eyes.
Conclusion. The minimum incidence of ARN in the UK is 0.63 cases per million. Patients with a history of herpetic CNS disease should be warned to immediately report any visual symptoms. There is increased use of oral and intravitreal antivirals in initial treatment.

Introduction

Acute retinal necrosis (ARN) is a rare but visually devastating condition. Standard diagnostic criteria from the American Uveitis Society consist of:^[1]

(1) one or more foci of retinal necrosis with discrete borders in the retina (Figure 1);
(2) progression of disease in the absence of treatment;
(3) evidence of occlusive vasculopathy; and
(4) an inflammatory reaction in the vitreous or anterior chamber.

Figure 1.

Enlarge

Acute Retinal Necrosis—Peripheral Retinal Necrosis with Discrete Scalloped Margin.

The diagnosis is therefore based not on aetiology but rather on clinical features. In recent literature most references to ARN assume a viral aetiology with other conditions that are subsequently identified as mimicking ARN. The human herpes viruses known to cause ARN are varicella-zoster virus (VZV), herpes simplex 1 and 2 (HSV1, HSV2), and, less commonly, cytomegalovirus (CMV) and Epstein-Barr virus (EBV).^[2,3] Progressive outer retinal necrosis (PORN) has been described as a similar syndrome with minimal inflammation in immunocompromised patients.

In this study we determine the minimum incidence of ARN in the United Kingdom and describe the demographic, clinical profile, investigations, management, and outcome of treatment in these patients