Purpose: To determine the causative virus in acute retinal necrosis (ARN) syndrome in a series of patients by calculation of modified Witmer coefficients.
Design: Noncomparative case series.
Participants: Ten patients with ARN syndrome from four medical centers.
Methods: Aqueous samples, vitreous samples, or both were collected prospectively during surgery from patients with a clinical diagnosis of ARN syndrome. Serologic measures of intraocular and serum antibodies to potentially causative viruses were measured by enzyme-linked immunosorbent assay.
Main outcome measures: Modified Witmer coefficients (immunoglobulin G and immunoglobulin A) for herpes simplex virus types 1 (HSV-1) and 2 (HSV-2), varicella zoster virus (VZV), and cytomegalovirus (CMV), as well as adenovirus type 2, were calculated from aqueous or vitreous samples, or both.
Results: Intraocular antibody measurements were strongly suggestive of a single diagnosis in 9 of 10 patients tested. Modified Witmer coefficients demonstrated intraocular antibody production to HSV in five patients and antibodies to VZV in four patients, and the measurement was inconclusive in one patient. No patients were positive for adenovirus or CMV. Strain-specific antibody titers demonstrated that all HSV-positive patients were reactive only to HSV-2. Herpes simplex virus type 2 was found predominantly in younger patients with ARN syndrome (mean age, 21.2 +/- 10 years; range, 17-39 years), whereas VZV was more commonly seen in older patients (mean age, 40.8 +/- 12.2 years; range, 29-58 years; P = 0.033). Immunoglobulin A testing confirmed immunoglobulin G testing in all patients examined.
Conclusions: Although VZV is thought to be the most common cause of ARN syndrome, HSV-2 is an important cause of ARN syndrome, particularly in younger patients. Because infection with HSV-2 has important medical ramifications, these results suggest that determination of a causal agent should be considered in some cases of ARN syndrome.