The tonometer is an instrument to measure the fluid pressure within the eye. It is most helpful in evaluating the eyes in breeds of pets genetically prone to glaucoma and certainly very important in all cases when glaucoma or infection within the eye is suspected. The eye is first anesthetized with a drop and then the tonometer pen is gently touched to the eye. This is very painless and takes only seconds to perform, but it provides us with a wealth of information to help manage your pet’s health.