Applanation tonometers are medical devices used to measure intraocular pressure (IOP) in the eyes. They work by flattening a small area of the cornea and measuring the force required to achieve this flattening. This helps assess the risk of glaucoma, a condition that can lead to vision loss if not monitored and treated. There are different types of applanation tonometers, including the Goldmann tonometer, which is commonly used in eye clinics. These devices are essential for eye care professionals to evaluate eye health and determine appropriate treatment plans for patients with elevated IOP.