A tonometer is a medical device used to measure the pressure inside the eye, known as intraocular pressure (IOP). This measurement is crucial for diagnosing and monitoring conditions like glaucoma, which can lead to vision loss if not treated. Tonometers can be classified into different types, including applanation tonometers and non-contact tonometers, each using different methods to obtain accurate readings. The procedure for using a tonometer is typically quick and painless. In a clinical setting, an eye care professional may apply a numbing eye drop before using the device. Regular eye exams that include tonometry are important for maintaining eye health, especially for individuals at higher risk of eye diseases.