How is a tonometry done?

According to tonometry that you want to perform different types of tonometer will be needed. Depending on the type of tonometer used, tonometry is classified as: Contact tonometry, which in turn is classified as:

• Flattening tonometry or Goldmann: consists of the indirect measurement of intraocular pressure by using a tonometer placed in a slit lamp. It is the most commonly used method.
• Rebound tonometry: consists of the indirect measurement of intraocular pressure through the emission of a microscopic metallic probe directed against the cornea; the measure of the speed at which the probe stops when it hits the corneal surface will give us the value of the intraocular pressure.
• Non-contact tonometry or pneumatic tonometry: consists of directing a small stream of air towards the cornea in order to flatten it, the measurement of the air pressure necessary to flatten the surface of the cornea will give us the value of the intraocular pressure.

Others: phosphene tonometry, palpebral tonometry, tonopen XL. (Less used)

How is tonometry performed?

• In flattening tonometry the ophthalmologist instills an anesthetic drop in each eye and uses fluorescein dye during the study; the patient remains seated without moving in a semi-dark room leaning on the slit lamp, avoid blinking and follow the instructions while the doctor performs the measurement.
• In rebound and non-contact tonometry the patient remains seated without moving in a semi-dark room while the ophthalmologist brings the tonometer closer and proceeds to the measurement; You should avoid blinking and follow the instructions while the doctor is taking the measurement. It does not require the use of anesthetic or fluorescein dye.

The use of one or the other technique will depend on the experience of the ophthalmologist and the material available to him.

Preparation for the exam

The exam usually lasts 5 minutes.It does not require prior preparation by the patient but you must inform your ophthalmologist if you have any type of systemic or ocular disease, especially conjunctivitis or corneal ulcer and / or glaucoma, if you take any type of medication and what medication it is and if you suffer from some kind of drug allergy. If the patient is a contact lens wearer, the ophthalmologist will ask for their removal before performing the test.

What does it feel like during and after the study?

• The flattening tonometry It is painless because the ophthalmologist instills a few drops of anesthetic eye drops in each eye prior to performing the test. Since it is necessary to use a fluorescein eye drop during the study, the conjunctiva of both eyes will be stained yellow-orange for a few hours.
• The rebound and non-contact tonometry they are painless and do not require the use of anesthetic or fluorescein.

Risks of tonometry

allergy to the drugs used during the examination (in the flattening tonometry). Irritation or tearing immediately after administration of anesthetic eye drops or fluorescein (on flattening tonometry)

Study contraindications

This study has no contraindications

What is the study done for?

The study of intraocular pressure is a simple and safe technique that allows detecting an increase in the levels of tension within the eyeball as well as monitoring them. A sustained or very sudden elevation of intraocular pressure levels can lead to irreversible damage to the optic nerve that can lead to partial or complete loss of vision.

The tonometry It is a test used to aid in the diagnosis and follow-up of the Intraocular pressure figures and the blood pressure figures are independent, although some patients may also present high intraocular pressure figures.