Intraocular pressure

A patient undergoing intraocular pressure measurement with a tonometer.

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A Diaton tonometer, a device used to measure intraocular pressure.

Intraocular pressure (IOP) is the fluid pressure inside the eye. It is an important aspect of eye health and is a critical factor in the diagnosis and management of glaucoma.

Physiology

Intraocular pressure is determined by the balance between the production and drainage of aqueous humor, the clear fluid inside the eye. The ciliary body produces aqueous humor, which flows through the pupil into the anterior chamber of the eye and drains out through the trabecular meshwork and Schlemm's canal.

Measurement

Intraocular pressure is measured using a device called a tonometer. There are several types of tonometers, including the Goldmann applanation tonometer, which is considered the gold standard, and the non-contact tonometer, which uses a puff of air to measure pressure. The Diaton tonometer is a transpalpebral tonometer that measures IOP through the eyelid.

Normal Range

The normal range for intraocular pressure is typically between 10 and 21 mmHg (millimeters of mercury). However, what is considered "normal" can vary between individuals, and some people with pressures outside this range may not have any eye disease.

Clinical Significance

Elevated intraocular pressure is a major risk factor for glaucoma, a group of eye conditions that can lead to optic nerve damage and vision loss. Monitoring and managing IOP is crucial in patients with glaucoma to prevent progression of the disease.

Factors Affecting Intraocular Pressure

Several factors can influence intraocular pressure, including:

• Age: IOP tends to increase with age.
• Genetics: Family history can play a role in IOP levels.
• Medications: Certain medications can increase or decrease IOP.
• Time of day: IOP can fluctuate throughout the day.

Management

Management of elevated intraocular pressure often involves medications such as prostaglandin analogs, beta blockers, or carbonic anhydrase inhibitors. In some cases, surgical interventions like trabeculectomy or laser therapy may be necessary.

Also see

• Glaucoma
• Aqueous humor
• Tonometry
• Optic nerve