Intraocular pressure (IOP) is the pressure inside the eye at a given point of time. The normal range in healthy eyes is thought to be between 10 and 21 mmHg however eyes with IOP outside this range may still be healthy. Increased IOP is a risk factor for glaucoma, an eye condition characterised by a damaged optic nerve.
Tonometry is a process that measures your IOP by determining the firmness of the surface of the eye. The procedure is performed under local anaesthesia by instilling eye drops. A tonometer consists of a light emitter, a pressure indicator and a microscope. A beam of blue light is emitted on the eye and the pressure sensor is slightly pressed against the cornea of the eye. The eye’s resistance to the sensor pressing against it is recorded as IOP. This procedure is sometimes repeated several times throughout the day as the pressure in the eye varies.