What is it?
Tonometry is the measurement of intraocular pressure (IOP) which is the pressure of fluid within the eyeball. This can be either contact or non-contact depending on the instrument used. At the London Eye Hospital we use the Goldmann & Tonopen contact tonometers. Raised IOP can damage nerve fibres within the eye leading to conditions such as glaucoma.

How is it done?
A drop of anaesthetic is placed in the eye before this test is performed. A probe is used to gently applanate the cornea to take the IOP measurements. This test may be repeated a few times to gain an average measurement. This test will take only a few minutes to perform.

Before your appointment:
Tonometry will need to be done without your contact lenses in.

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