EVERY ophthalmologist is interested in some sanitary method of using the tonometer so that the instrument will not transfer an infection from one patient to the next. Various techniques have been used. These included wiping the plunger with etheralcohol mixtures, ether alone, or alcohol alone. The tonometer stand that kept the plunger constantly immersed was discarded because fluid got between the plunger and the footplate and rose by capillary action. It was felt that this fluid impeded the accuracy of the reading. Some men just wash their instruments in hot water. I have developed a tonometer "sterilizer" that employs ultraviolet radiation-ozone exposure close to the tip. This instrument was made with the cooperation of Dr. L. J. Buttolph and staff at Nela Park, General Electric Lamp Division, Cleveland. The following data are taken from LD-14, G. E. Ultraviolet Sanitation Booklet, page 6: We employ a small mercury vapor lamp using