Tonometry is a medical test used to measure the pressure inside the eye, known as intraocular pressure (IOP). This test is essential for diagnosing and monitoring conditions like glaucoma, which can lead to vision loss if not treated. During tonometry, a healthcare professional uses a specialized instrument to gently touch the surface of the eye or use a puff of air to assess the pressure. The results help determine if the eye pressure is within a normal range, guiding further evaluation or treatment if necessary.