Correlation of varicella-zoster virus copies and final visual acuities of acute retinal necrosis syndrome

Background: Herpes viruses may play an important role in acute retinal necrosis (ARN) syndrome, and raised antibody titer or virus genome have been detected in intraocular fluids of patients with ARN. In spite of aggressive anti-viral therapy, the clinical courses and final visual acuities among these patients have varied. Our purpose was to estimate the amount of virus and compare it to final visual acuity in patients with ARN. Methods: The number of varicella-zoster virus copies in aqueous and vitreous before and after administration of anti-viral therapy were estimated by polymerase chain reaction (PCR) and by semi-nested PCR in 12 eyes of 11 patients with ARN and were compared with clinical characteristics. Results: Viral genome DNA was amplified in ocular fluids diluted between 10^-3 and 10^-6 in patients whose final visual acuities were 0.3 or less. Conversely, the dilution required was between 10^-1 to 10^-3 in the patients whose final visual acuities were 0.4 or better. The difference was statistically significant. Further, patients in the latter group reacted to the anti-viral drug acyclovir more promptly than did the former patients. Conclusion: Our results showed that final visual acuity may partly depend on the number of virus copies in ocular fluids. The number of virus copies tended to be higher in elderly or immunocompromised patients than in others, and the treatment was less efficacious in these patients.