Sensitivity to acyclovir in acute retinal necrosis syndrome

We reviewed 8 unilateral cases of acute retinal necrosis syndrome treated by systemic acyclovir. All were positive for herpes zoster virus. The final visual acuity was 0.2 or less in 5 eyes and 0.4 or better in 3 eyes. Cases with fair final visual acuity were characterized by lesser amount of virus in the aqueous fluid estimated by polymerase chain reaction (PCR). The amount of virus further decreased after treatment by acyclovir. The findings suggest that cases of acute retinal necrosis syndrome can be classified into moderate type which responds to acyclovir and more fulminant type which is more common in aged or immunocompromised patients.