SU1430028A1 - Mechanical tonometer with light indicator - Google Patents

Abstract

The invention relates to a mechanical tonometer. According to the invention, it includes a body 1 with a foot 2, a graduation 3, set inside the body on the side opposite the foot 2, and a plunger 4 which can move in the body 1; by means of the foot 2 the plunger 4 interacts with the cornea 27 of the eye to be examined; inside the body 1 there are received a light source 7, 8 and a reflecting mirror 9 which is connected to the plunger 4; the internal cavity of the plunger 4 is made of a light-conducting material. The invention finds its application in ophthalmology. <IMAGE>

Description

The invention relates to Yap instrumentation for measuring intraocular pressure.

The aim of the invention is to improve the accuracy of measurement of intraocular pressure.

FIG. 1 schematically shows the following: a blood pressure monitor; in fig. 2 - section A-A in FIG. one; in fig. 3 - the site of contact of the plunger and the reflecting grain. the node I in FIG. one; in fig. 4 - a tonometer with a light pointer and Holder at the lateral location and a source of light, option; in fig. 5 - p; notching bb in fig. four.

I The tonometer consists of a plunger 1 that can be moved relative to the housing 2 in bearings 3 quintals 4. In the lower part of the housing there is an arm; 5, in contact with the horn of the examined eye. On the plunger 1 {additional weights can be installed. The plunger stroke is limited by a pin 6. In the upper part of the housing 2, there is a light source 7 (for example, an electric lamp) and a condenser 8 mounted at a focal distance from the light source 7 and directing the light beam to the mirror 9. In the upper part of the housing 2 is fixed a scale 10 on which a beam of light forms, which forms a light mark reflected from mirror 9. Mirror 9 can rotate about axis P, fixed in supports 12, under the action of movement of plunger 1, in the end part of which there is a needle 13, installed in to the conductive material 14 of the inner part of the plunger 1. The material of the inner part of the plunger is in direct contact with the cornea of the examined eye. In the vicinity of the contact of the needle 13 and the mirror 9, the reflective layer 15 is removed, resulting in a transparent window through which part of the light incident on the mirror 9 can pass through and enter the light-conducting material 14. The device has a holder 16 on which contact groups 17 are located power source 7 light.

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The device works as follows.

With base 5, the tonometer is placed on the cornea of the patient's eye. Under the action of its own weight, (with an additional weight), the plunger 1 occupies a certain position relative to the housing 2, at which the mirror 9 turns a certain angle about {relative to the axis I1. The light from source 7 through condensate 8, reflected from mirror 9, creates a light mark on the scale 10. The position of the light mark is proportional to the angle / rotation of the mirror, and therefore to the amount of movement of the plunger 1 relative to the housing 2. Indeed, the coordinate change light mark on the scale (dx) is associated with a change in the position of the plunger (DN) by the ratio

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where H is the distance from the surface of the reflecting mirror to the surface of the scale;

h is the distance from the center of the contact needle to the center of the axis about which the reflecting mirror is rotated. The second term of the ratio can be neglected due to its insignificance. Thus, the conversion factor is determined by the distance from the mirror to the H scale and the distance h, i.e. increase in sensitivity is not associated with an increase in the reduced mass. Therefore, in this tonometer it is possible to observe the magnitude of the pulse oscillations. The scale is graduated in units of Shiotsa. A part of the light incident on the mirror 9 through the window and through the light-conducting material into the patient's eye creates light 6 times with the correct position of the device relative to the cornea. The patient is asked to constantly observe a light image, as a result of which the eye is fixed. With the help of the holder 16, the device is held in the patient's eye in a working condition.

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Claims (2)

MECHANICAL TONOMETER WITH LIGHT INDICATOR, consisting of a body with a base, a plunger having the ability to move relative to the body, scale and light source, characterized in that in order to increase the accuracy of measuring intraocular pressure, the tonometer is equipped with a condenser and a mirror, the mirror is installed with the possibility of turning and interacting with a needle mounted on the plunger, the plunger having an internal light guide part, and a window for passing light into the eye of the patient is made in the surface of the reflective layer of the mirror NTA. ke 2.