TONOMETERS

From Big Medical Encyclopedia

TONOMETERS in an oft of m of au l about and and (Greek tonos tension] - metreo to measure, measure) — devices for measurement of intraocular pressure. The principle of a research consists in measurement of deformation of an eyeglobe under the influence of pressure of a certain weight (weight).

Depending on a form of deformation of an eyeglobe distinguish ap-ilanatsionny and to them a press ionic T. P r and it is used by NP anpl anatsioi-ny T. intraocular pressure is determined by the size of flattening (ap the plan of the CPU and) by corneas, impression — by extent of impression by its plunger (core) of the device (see Tonometriya).

First T. offered in 19 century A. Gref (1863), Dore (H. Dor, 1865), Weber (A. Weber, 1867), etc. All of them were impress.ionny. Measurements of intraocular pressure were performed on a sclera, were a little reliable and were almost not applied in a wedge, practice. In 1884.

A. N. Maklakov suggested to perform measurements of intraocular pressure on a cornea to applanation T. own design. This method found broad application.

Maklakov's tonometer represents the hollow metal cylinder 4 cm high, weighing 10 g; its bases are expanded and have platforms from milky-white or ground glass to dia. 10 mm, the looplike handle allows to hold the case T. at a research in vertical position (see fig. 3 to the Art. of Tonometriya). The imprinted circle of flattening of a cornea is transferred to paper and measured by a special ruler with designation of intraocular pressure in millimeters of mercury.

In addition to Maklakov's tonometer, the medical industry, releases also a set of tonometers weighing 5 of Maklakov; 7,5; 10 and 15 g for an elastotonometriya by Filatov's method — Kalfy. The method of an elastotonometriya consists in consecutive measurement of intraocular pressure four tonometers; by results of a research draw a curve, character a cut reflects a condition of covers of an eye.

T., the designed Goldman nomas (H. Goldmann, 1954), represents advanced m ikrokontaktny anpl an anatsionny tonometer (fig. 1) strengthened on a slit lamp (see). Appl the nation of a cornea is made at very small sizes of pressure, and the circle of flattening of a cornea is measured under a microscope. The area of deformation of an eye during the use of microgame-stroke tonometers is extremely small (the volume of the intraocular liquid which is forced out at a tonometriya apprx. 0,5 mkl). Thanks to it results of measurement as much as possible approach the size of true intraocular pressure. Manual options T are offered. like


Fig. 1. Goldmann's tonometer strengthened on a slit lamp: 1 — the case of a tonometer; 2 — a lens Be rude for a direct oftalmoskopiya; z — system of levers for change of provision of a prism of a tonometer; 4 — the part of a tonometer contacting to an eye (prism); 5 — the lighter of a slit

lamp; 6 — the binocular microscope.

Goldmann's tonometer, the researches allowing to make both in horizontal, and in vertical position of the patient.

Applanation pnev-moelektrichesky T are known., supplied with the sensors pneumatically connected with the electronic sensator, registrars and system of digital reading of results.

The main device impreseion-ny ooze for measurement of intraocular pressure is T., offered by Shyotts (H. Schiotz, 1905), or its technically improved versions (fig. 2). Working part T. it is executed in the form of the cylindrical case, the lower end to-rogo has slightly concave platform (part T contacting to an eye.). According to the center of the platform for an axis of the cylinder in the channel the plunger weighing 5,5 g and to dia freely moves. 3 mm; there are also additional loads which if necessary are put on a plunger


of Fig. 2. Shyotts's tonometer: 1 — a scale that

a nometra; 2 — the part of a core (plunger) of a tonometer contacting to an eye; z — an additional load for increase in the created loading; 4 — the case of a tonometer. *

to increase its weight to 7,5;

156 TONOMETERS FOR the HEMODYNAMOMETRY


of 10 and 15 g. During the research under the influence of a load the plunger is pressed into a cornea on a certain depth, it is noted edges by a finger of a device. The result is read out on a scale and make recalculation according to gage tables.

See also Tonometriya.

Bibliography: Jobbers And. N. Of

talmotonometriya, Medical obozr., t. 22, No. 24, page 1092, 1884; Go! dmann H.& Un nouveau tonomMre applanation, Bull. Soc. frang. Ophtal., t. 67, p. 474, 1954;

S with li i 6 t z H. Ein neuer Tonometer, Arch. Augenheilk., Bd 52, S. 401, 1905. See also bibliogr. to the Art. of Tonometriya.

V. M. Budnik, B. I. Vagin, A. A. Stetsin.

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