Observation of varicella zoster virus-induced acute retinal necrosis: viral load detection and visual outcome

Objectives: To observe the changes of viral load in aqueous humour samples and visual outcomes in varicella zoster virus (VZV)-induced acute retinal necrosis (ARN). Methods: Observational retrospective study. Medical records and viral load measured by real-time quantitative polymerase chain reaction (qPCR) of 20 eyes with VZV-induced ARN were reviewed. Results: The mean viral load at presentation was 5.7 × 10⁷± 9.7 × 10⁷copies/mL. An initial plateau phase for viral load lasting up to 2 weeks occurred in most eyes (18 eyes, 90%). In the following logarithmic reduction phase, the mean slope of the decline in viral load was −0.103 ± 0.029 log/day, and the expected time for half reduction of the initial viral load was 3.2 ± 1.0 days. At the end of the first 8-week’s antiviral treatment, the viral load was below detection threshold in all 20 eyes (100.0%). The mean logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) improved from 1.1 ± 0.7 (Snellen equivalent 20/250) to 0.7 ± 0.6 (Snellen equivalent 20/100) after a follow-up of 8.6 ± 2.0 months. Thirteen of the 20 eyes (65.0%) suffered retinal detachment and underwent vitrectomy. The initial viral load was the independent predictive factor of logMAR BCVA at the last follow-up (β= 0.745, P< 0.001). Conclusions: The observation of viral load changes by qPCR was useful for better monitoring of therapeutic efficacy and deciding needed antiviral duration in VZV-induced ARN patients.