Intraocular Pressure Measurement (IOP) is a test used to assess the pressure inside the eye. This measurement is crucial for diagnosing and monitoring conditions like glaucoma, which can lead to vision loss if not treated. The pressure is typically measured in millimeters of mercury (mmHg) using various methods, including tonometry. The most common technique is applanation tonometry, where a small probe gently flattens a part of the cornea to determine pressure. Other methods include non-contact tonometry, which uses a puff of air, and indentation tonometry, which involves pressing on the eye. Regular IOP checks are important for maintaining eye health.