Dealing with the classical “red eye” may be more than a routine eye infection or conjunctivitis. In fact, there are a group of eye disorders that we consider to be urgent or emergency in nature and the ability to properly treat these cases requires accurate measurement of the internal eye pressure (IOP or internal ocular pressure). This is a quick and accurate method to measure internal eye pressure and differentiate between those disorders than cause low pressure (e.g. uveitis – of which some progress to glaucoma) and those than cause high pressure (e.g. glaucoma). It is routinely performed in the examination room with the owner present and is well tolerated by most dogs and cats. We do this by initially “freezing” the cornea or eyeball surface with special drops. We then gently “tap” the surface of the eye with a state-of-the-art hand-held Rebound Tonometer calculates the internal eye pressure. This procedure is used as a screening test for glaucoma, as a diagnostic test for suspected glaucoma, and as a monitoring procedure to judge our glaucoma therapy. It is a quick and painless procedure that is extremely accurate especially when compared to previous techniques.