Viability of herpes simplex virus type 1 on the applanation tonometer

We performed several experiments to define possible factors that influence the viability of herpes simplex virus type 1 on the applanation tonometer. Infectious virus could be detected on experimentally inoculated tonometer heads for up to two hours during natural drying. If tonometers were kept moist the virus could be detected more than eight hours later. Several ophthalmic solutions, including topical anesthetics, dilating agents, and a fluorescein solution, showed only minimal antiviral activities. Wiping of virus-infected tonometer heads with a dry tissue was ineffective and allowed residual infectious virus to remain. However, no infectious virus could be detected on infected tonometer heads that had been swabbed with 70% isopropyl alcohol. Our results raised concerns regarding effective disinfection of tonometers after eye examinations. We concluded that the applanation tonometer should be swabbed routinely with alcohol after each patient examination to ensure complete virus inactivation and to prevent accidental transmission of virus in the clinical setting.