Abstract
Purpose :
Acute Retinal Necrosis (ARN) is a rare viral retinitis affecting immunocompetent individuals. The aim of this retrospective study was to investigate the characteristics of patients diagnosed with ARN and to determine the relevance of virus type and viral load as prognostic factors.
Methods :
Thirteen patients were diagnosed with ARN between 2007 and 2016 at the Department of Ophthalmology at Sahlgrenska University Hospital, Mölndal, or at the Department of Ophthalmology at Hallands hospital, Halmstad, Sweden. Patients had to meet all the criteria of ARN as stated by the American Uveitis Society as well as being PCR-positive in aqueous or vitreous humor for varicella zoster virus (VZV), herpes simplex virus 1 or 2 (HSV1/HSV2). Serum and aqueous or vitreous were analysed with quantitative Taqman PCR and serum was analysed for IgM and IgG for herpes viruses. Linear regression was performed to determine possible associations between viral load and final visual acuity at follow-up.
Results :
PCR analysis of ocular fluids identified 6 cases with VZV, 4 cases with HSV1 and 3 cases with HSV2. Medical journals of patients tested positive for epstein barr virus (n=2) or cytomegalovirus (n=13) were also reviewed and none of these exhibited signs of ARN.
Patients with VZV ARN were older than HSV ARN; mean age 60.5 (SD 5.0) as compared to 45.4 (SD 15.9), p=0.049. HSV 1 ARN occurred in patients who had herpes encephalitis in childhood in two out of four cases. All patients had IgG for the specific virus in serum indicating a reactivation. Two of 13 patients had viremia at presentation. A rise of ARN was seen in the summer. Linear regression analysis showed no correlation between high viral load and worse visual prognosis (intercept=0.913, beta=0.03, R2=0.054, p=0.469)
Conclusions :
Our study suggests that ARN is a reactivation of alpha herpesviruses (VZV, HSV 1 and 2). These viruses exhibit similar clinical signs of ARN but affect patients with different characteristics. We did not find a correlation between viral load and visual acuity in our material. Many factors contribute to viral load such as type of ocular sample (vitreous or aqueous) and duration of symptoms. In spite of being a localized disease in a small compartment, viremia can occur in some patients. Our results may implicate UV-light as a possible factor in reactivation of VZV as well as HSV.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.