During a routine eye test, the ophthalmologist will need to test your intraocular pressure, known as IOP. This is done with a tonometer. Measuring the fluid pressure in the eye is important in the evaluation of a patient for glaucoma.
A non-contact tonometer is the best way for patients to have this test as it is quick and painless. This instrument measures the eye pressure with an air-puff test. The air that bounces back from the eye ball gives the machine a reading to tell what the eye pressure is. The alternative, more traditional tests produce the same results but are more time-consuming. Some doctor uses another machine called the Goldmann tonometer to measure the eye pressure. First the doctor will apply a drop of anesthetic into your eye to numb it. He will then add a drop of fluroscein which is a yellow dye. You will be asked to place your chin on a support in front of the tonometer which will hold your head steady. The doctor looks through the side with binocular type equipment. The tonometer is moved close to the eyeball until a probe touches the cornea. It then measures the inner pressure of the eye. Raised intraocular pressure can be the first signs of glaucoma. If your eye pressure is higher than it should be, you may be at risk of developing glaucoma
Testing for Glaucoma
Glaucoma is the name given to a group of conditions which result in damage to the optic nerve. Intraocular pressure inside the eye is often the cause of this damage with a resulting reduction in vision. Glaucoma damages sight so gradually that it is often only detected when it is in an advanced stage, or by testing for raised intraocular pressure. It is estimated that 65 million people worldwide suffer from glaucoma. Early diagnosis is crucial to minimize or prevent damage to the optic nerve.
Doctors understand that damage to the optic nerve is caused by intraocular pressure, but they do not yet fully understand why that pressure is associated with this damage, a main characteristic of glaucoma. Research is still underway to find out how to prevent or stop this deterioration in the retinal ganglion cells. The pressure comes from the fluid, called aqueous humor, which is normally produced in the front of your eye. Aqueous humor normally drains away through a small drainage system between the iris and the cornea. When this drainage fails to function properly, the aqueous humor builds up and pressure builds within the eye. The simple air puff test is the best and easiest way to detect this problem and begin preventative measures to prevent glaucoma.
