There are several methods of testing for glaucoma. In the Schiotz method, you will be lying on a table. Loosen any tight clothing around your neck (tightness may increase the pressure inside the eyes). You will be asked to look down as the upper eyelid is raised and a drop of anesthetic is placed in the eye. You then need to look at a spot on the ceiling. A tonometer (a small, smooth instrument) is lowered onto the surface of the eye for a few seconds. The procedure is then repeated for the other eye. This method is rarely performed today, but in some circumstances is useful.
The applanation method measures the force required to flatten a certain area of the cornea. A fine strip of paper that is stained with an orange colored dye (fluorescein) is touched to the side of the eye. The dye stains the front part of the eye to help with the examination. The dye rinses out of the eye with tears. An anesthetic drop is also placed in the eye. The slit-lamp is placed in front of you and you rest your chin and forehead on the support that keeps your head steady. The lamp is moved forward until the tonometer touches the cornea. The light is usually a blue circle and there is no discomfort associated with the test. The health care provider looks through the eyepiece on the lamp and adjusts the tension on the tonometer.
A slightly different method of applanation uses a portable object similar to pencil. Again the person is given anesthetic eye drops to prevent any discomfort. The device touches the outside of the eye and an instant digital measurement is recorded.
The last method is the noncontact method (air puff). In this method, your chin is resting on a padded stand. You will be asked to stare straight into the examining instrument. The examiner will shine a bright light into your eye to properly aligned the instrument. A brief puff of air is blown at your eye. The instrument calculates pressure from the change in the light reflected off the corneas as the air puff is blown.
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