An important diagnostic measure for the detection of various pathologies of the eyes, including glaucoma , is the measurement of intraocular pressure or ophthalmotonus. It consists in establishing the ratio of outflow and inflow of liquids in the chambers of the eye. This examination must be done once a year, especially for women after reaching the age of 40.
Methods for measuring intraocular pressure
In ophthalmic practice, two basic techniques for determining the ophthalmotonus are used:
- palpation;
- instrumental.
The first method allows to obtain an approximate assessment of intraocular pressure. It consists in pressing fingers on the eye (the eyelids are closed at the same time), creating intermittent jerks of the eyeball down.
The second technique involves the use of special devices.
Measurement of intraocular pressure using a Maklakov tonometer and other contact techniques
The most common technology for determining the ophthalmotonism in the Soviet times was the measurement according to Maklakov. It is worth noting that now it is somewhat outdated, and for the procedure use a similar device - elastotonometer Filatov-Kalfa. It is a small cylinder (weight) weighing 10 grams with plastic plates at the ends. The device is also equipped with a holder that allows the cylinder to move freely down and up.
The essence of the procedure is to exert mechanical pressure on the eye. The amount of moisture displaced at the same time allows setting the value of the ophthalmotonus.
A similar mechanism of operation underlies more modern tonometers for measuring intraocular pressure:
- Goldmann;
- ICare and ICare Tiolat (portable device);
- Pascal.
Non-contact tonometers for measuring intraocular pressure
Patients of ophthalmology prefer a more comfortable way to establish an ophthalmotonus - contactless. This technique is no less informative than the contact technique, but requires more measurements and subsequent averaging.
The operation of a contactless device for measuring intraocular pressure consists in feeding a stream directed to the cornea, which displaces a certain volume of fluid from the eye cells.