Taking a reading of a patient’s intraocular pressure is the first step in identifying the onset of glaucoma. High pressure in the eyes leads to high pressure upon the optic nerve, which damages the cells of those nerves and impedes the eyes’ ability to communicate with the rest of the brain. The necessity and sensitivity of measuring eye pressure have led to multiple approaches in taking those measurements. Here are the three most prevalent methods of measuring eye pressure in an ophthalmologist’s office.
Stationary Applanation Tonometry
Applanation tonometry using a stationary tonometer, or a Goldmann tonometer, is the gold standard of measuring intraocular pressure. After anesthetizing the surface of the eye and applying a dye, the tonometer probe contacts the cornea while the instrument measures the amount of pressure necessary to flatten the cornea. While any eye exam requires a patient to sit still, sitting before a Goldmann tonometer can be particularly demanding. The inflexibility and inaccessibility of Goldmann tonometry means that despite being the gold standard for IOP, alternative methods for measuring eye pressure exist.
Handheld Applanation Tonometry
Handheld applanation tonometry takes the underlying principle of Goldmann tonometry—that doctors can measure intraocular pressure by calculating the resistance of the cornea to pressure—but transfers it into a device that can measure eye pressure for almost anyone, not just those are who are capable of undergoing examination on a Goldmann tonometer. The Reichert Tono-Pen condenses the instruments into a device that can meet patients where they are. As long as the patient does not have a latex allergy that would preclude the use of the Tono-Pen tip covers that keep the probe sanitary, the versatility and ease of use makes the Tono-Pen a useful alternative.
Non-Contact (Air Puff) Tonometry
Some patients cannot tolerate local anesthetic on the eyes. Others may be apprehensive about even a handheld probe making direct contact with the surface of the eye. To accommodate sensitive patients such as these, the least invasive method of measuring eye pressure is non-contact tonometry, or air-puff tonometry. Air puff tonometers deliver a quick blast of air to the cornea and measures the resistance of the cornea to the air without making direct contact. While this method sacrifices accuracy in the name of accommodation, it’s still a useful protection against the encroachment of glaucoma.