Testing your eye pressure, also known as intraocular pressure or IOP, is an integral part of a comprehensive eye exam and a primary reason to see your optometrist regularly. Frequency of eye examinations can vary depending on each patients. Patients diagnosed with Glaucoma for example will require a closer monitor and more frequent visits than patients who are being monitored due to family history.
Commonly used methods to test eye pressure:
• Goldmann applanation tonometry
Goldmann applanation tonometry is one of the most accurate techniques used to check the eye pressure. It is still the gold standard for measureing intraocular pressure (IOP) in glaucoma patients. This technique examines your eye pressure by determining the amount of force required to flatten a corneal surface area. Optometrists using this method to test eye pressure use a tonometer that consists of a tonometer arm, contact prism, contact probe, and measuring drum.
Before an optometrist starts checking your pressure, some detailed instructions highlighting the process are offered to the patient. Below is a complete procedure on how to go about this method. The procedure starts by instilling anesthetic drops and small amounts of fluorescein into the eye. Once the patient is ready and situated in the slit lamp the probe is gently moved towards the corneal centre. One the tip touchs the cornea the knob is adjusted until the edges of the two mires are just touching. Once this is achieved the reading obtained is recorded. This represents the amount of pressure taken to flatten the surface.
• Tono-Pen tonometry
Tono-Pen tonometry is a method of testing the eye pressure where an optometrist touches the cornea with a pen tip until a reading is displayed. This method is not only accurate but also reliable and it's used in many clinical settings. One advantage of this instrument is it's mobility and portability. It's great for patients who are wheelchair ridden and have limited mobility. An optometrist can repeat the procedure several times if the final measurements differ by more than two mmHg to ensure an accurate measurement is obtained.
• Non-contact tonometry (NCT)
Non-contact tonometry (NCT) is a method of testing the eye pressure that works on a time-interval principle. Optometrists’ uses the tonometer to measure the total time it takes from the first generation of the puff of air to where your cornea flattens. Note that it takes milliseconds for a puff of air to obtain the reading. This method is commonly used in screenings and as a part of a pretest in routine examinations.
Why is it essential to test for eye pressure?
Testing for eye pressure helps in determining the risk for glaucoma. Undetected elevated pressure in the eye can lead to glaucoma, an eye condition that's characterized by a damage to the optic nerve. It’s never too late, book an appointment with your optometrist to have your eyes checked. Make it a routine to stay safe and healthy.