Tonometry  is a clinical technique that provides a measurement of the eye , which includes the combined resistance to deformity of its coats and the intraocular pressure (IOP).

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Tonometer is the device used for measuring the Intra ocular pressure. Tonometry is a quick and simple test that checks the pressure inside your eyes. The results can help your doctor see if you’re at risk for glaucoma.

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Glaucoma is a disease in which the nerve of the eye (the optic nerve) is gradually damaged over time, resulting in a loss of vision. This disease is often associated with increased eye pressure. Identifying this elevated eye pressure and trying to lower it is the only known way to prevent blindness from glaucoma. Early screening can help protect your eyesight and slow down vision loss.

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Anyone can get glaucoma, but your odds are higher if you:

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• Are over 40

• Have a family member with glaucoma

• Are African, Hispanic or Asian

• Have had an eye injury

• Are far-sighted or near-sighted

• Have been told your corneas are thin in the middle

• Have diabetes

• Get migraines

• Have circulation (blood flow) problems

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  Variations of Intraocular pressure

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 1. Physiological variations : the IOP normally fluctuates 2-5mmHg throughout the day  with respiration and heart beat along with the venous and arterial pressure.

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2. Local mechanical factors :

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• dilatation of the pupil

• changes in the solid content of the eye

• pressure from outside

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3. Pharmacological factors: The ciliary muscle is inserted into the trabeculae , so the contraction of the ciliary muscle makes the trabecular meshwork more porous -> increases the facility of outflow -> reduces IOP

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• outflow facility

• reduction of aqueous production

• atropine