Indications:

• to measure intraocular pressure – normal IOP -12 – 21 mmHg
• perform after visual acuity testing

Contraindications:

• ​suspected globe rupture or penetrating injury
• ​history of recurrent corneal erosions
• ​severe bullous keratopathy
• corneal abrasions
• ​corneal oedema
• severe band keratopathy

Complications:

• Transient reduction in acuity following tonometry may occur

Equipment:

• Tonometer
• A simple, rapid and reliable method of measuring IOP
• Dedicated handheld device.
• ​A magnetic mechanism rapidly presses a small, soft probe against the cornea six times.
• The degree of corneal resistance is translated into an IOP estimate.
• ​Does not require local anaesthesia or a slit lamp.
• ​The patient must be sitting upright.

Using the tonometer- ICARE (Video courtesy ICARE USA)

Older eye care tonometer (Video Courtesy ICARE USA)

Procedure:

• Ask the subject to relax and look straight ahead at a specific point.
• Hold the tonometer in a horizontal position.
• ​Bring the tonometer near to the eye until the probe tip is 4-8 mm from the centre of the cornea.
• ​The forehead-support adjustment wheel varies this distance.
• Measure IOP by pressing the measurement button.
• ​After each successful measurement, there is a short beep.
• ​Perform six measurements.