Many people think of an eye chart, lenses, drops and maybe sometimes bright lights when an eye exam comes to mind. Some people might remember the air puff or the probe that gets close to their eyes when their eye pressure gets measured. However, not many know why it is important to have their eye pressure measured routinely.
What does high intraocular pressure do to the eye?
Eye pressure, or more precisely Intra-ocular pressure (IOP), is the number one risk factor for causing glaucoma. Elevated IOP can cause a direct damage to the optic nerve resulting in glaucoma. Glaucoma is a slow progressive disease that initially starts with no presenting symptoms. With time the damage to the optic nerve starts to cause peripheral vision loss, tunnel vision and eventually loss of sight if it goes undetected and untreated. Unfortunately, nerve tissue loss is irreversible and any vision loss can’t be brought back. This is why it is very critical to detect disease early and to treat it early to attempt to slow the progression or stop it. Elevated eye pressure typically has no symptoms and vision is not affected early on and during progression of the disease. Hence it is difficult for the patient to know if there is something wrong going on. This is the reason sometimes it’s referred to as the silent disease. It sneaks on the affected individual without any prior warning in terms of symptoms. However, with routine eye examination that includes the measurement of your intraocular pressure along with other test, it can be detected.
How is eye pressure measured?
Several methods can be used to measure the intraocular pressure. One common method that’s usually used during routine annual examination is the NCT, which stands for None Contact Tonometry. It’s an easy and minimally invasive test. It’s performed by blowing a small puff of air to measure the eye’s pressure through measuring the cornea’s resistance to the puff. Other methods involve hand held devices that contact the eye to take the measurement. These test are typically quick to do and can be done in most settings. The gold standard method to measure intraocular pressure is Goldman Applanation tonometry (GAT). GAT is based on the principle that the pressure inside the eyeball being equal to the force necessary to flatten inside its surface divided by the surface of flattening. The test is performed by instilling a drop of anesthetic into each eye first then a fluorescein dye is instilled. Once that’s completed the optometrist will use a tonometer prisms trip to contact the eye and adjust the dials as necessary to reach an accurate measurement of the pressure.
Next time you undergo your comprehensive eye exam make sure that your intraocular pressure is being measured. If you are looking to find an optometrist in the Toronto area contact us today and we will be happy to schedule you in for an eye exam.