RU64885U1 - NISTAGMOMETER - Google Patents

Abstract

The proposed utility model relates to medical equipment, namely to ophthalmology and is intended to measure the amplitude of horizontal nystagmus in the pre- and postoperative periods. The objective of the proposed technical solution is to create an inexpensive, easy to manufacture and use an effective device. A device for measuring the amplitude of horizontal nystagmus, which includes an element fixed on the patient’s head in the holder that records the amount of displacement of the eyeball, differs in that a scale mark equipped with a nose cut and an elastic tape is used as the holder, and as an element that records the amount of displacement of the eyeball apples, a restrictive ruler is used, made with the ability to move on the scale of divisions. The restrictive line is installed on the scale of divisions in the double-breasted channel. The number of restrictive rulers is preferably four. 3 of FIG.

Description

The proposed utility model relates to medical equipment, namely to ophthalmology and is intended to measure the amplitude of horizontal nystagmus in the pre- and postoperative periods.

Nystagmus is the most severe pathology of the visual system associated with disorders of the central nervous system, with pathology of the fundus and optic nerve. These are spontaneous, independent of human will oscillatory movements of the eyeballs. Since the disease is quite rare, there are few productive methods and devices for its diagnosis.

The most common device for diagnosing nystagmus at the present time is the electristagmograph [A.E. Kurashvili, V.I. Babiyak Electronistagmography. - L .: Medicine. Leningrad branch, 1970], with which the corneal-retinal potential oscillations are recorded in the form of an oculogram for recording cyclic eye movements, as a result of which it is possible to obtain a complete description of the parameters of nystagmus: amplitude, frequency, vectoriality, duration, angular velocity. The electrodes are attached: for recording horizontal movements of the eyeballs - at the outer corners of the eyes, for recording vertical movements of the eyeballs - in the area of the superciliary arch and at the lower edge of the orbit. The direction of the current changes simultaneously with a change in the rotation of the eyes, and its magnitude will depend on the angle between the visual line and the sagittal plane. Changes in the magnitude of the constant potential during eye movement are compared with the magnitude of the potential for the "standard" angle of rotation of the eye of the subject, as a result, you can quantitatively characterize the functions of the oculomotor apparatus.

In particular, in order to determine the amplitude of nystagmus, it is necessary to calibrate first. For this, the potential difference arising when the eyes are turned at a predetermined angle of 20 ° is electrographically recorded. The study is carried out by sitting the patient behind the perimeter, as is usually done in the study of visual fields. The patient is asked to open both eyes. The light mark (5 mm in diameter) is diverted from the midline by 20 °. Without turning his head, the subject should, on command, move his gaze from the center point to the designated mark, fixing it. After that, the patient should quickly turn his gaze to the central mark. At this time, the oculogram is recorded. The calibration oscillation has a characteristic

configuration. Its amplitude (A) in millimeters corresponds to a standard angle of 20 °; the amplitude of one nystagmus cycle (X) in degrees is found by the formula: , where a is the amplitude of the investigated nystagmine cycle in millimeters.

The disadvantages of the electrostagmograph are the complexity of its use and a rather high cost.

Known hardware-software complex for computer video diagnostics, designed to describe the nature of nystagmus and monitor the progress of its development [Usanov D.A., Skripal Al.V., Abramov A.V., Usanova TB, Skripal An.V. - Video diagnostics of involuntary eye movements. - http://virlib.eunnet.net/conferences/phbm/win/045.html - prototype]. The hardware and software complex includes a video camera that records the angular displacement of the eye in the orbit (amplitude of nystagmus, including horizontal). In this case, the patient’s head and the video camera are fixed in a special holder to ensure the video camera is stationary relative to the eye socket. With the help of an annular fluorescent lamp, uniform illumination of the eye is ensured, since the presence of glare on the pupil leads to the displacement of the recognized center from the center of the real one. The video image of the moving pupil is entered into the computer using an analog-to-digital converter and analyzed using the eyemotion.exe program.

The program recognizes the center of the object (in this case, the pupil) in the eye image and allows you to analyze the video image of a moving object entered into the computer or part of it: performs frame-by-frame threshold processing of the video file and records the trajectory of the center of the object, as well as its mathematical processing (spectral conversion).

The disadvantages of the prototype device are the complexity of its use and high cost (more than 300,000 rubles.). Due to the small number of patients treating this pathology with oculists, the purchase of a prototype device often remains unprofitable, therefore, devices are not purchased by medical institutions.

Since the most important of all the parameters of nystagmus is its amplitude, the objective of the proposed technical solution is to create an inexpensive, easy to manufacture and use an effective device for measuring the amplitude of horizontal nystagmus in the pre- and postoperative periods.

The problem is solved in that the device for measuring the amplitude

horizontal nystagmus, which includes an element fixed on the patient’s head in the holder that records the amount of displacement of the eyeball, differs in that the holder uses a scale of divisions equipped with a notch for the nose and an elastic tape, and a restrictive element used to record the amount of displacement of the eyeball ruler made with the ability to move on the scale of divisions.

The restrictive line is installed on the scale of divisions in the double-breasted channel.

The number of restrictive rulers is preferably four.

Figure 1 presents a preferred diagram of a nystagmometer, figure 2 is a side view of it. Here: 1 - scale of divisions (in millimeters); 2 - elastic tape; 3 - restrictive rulers, 4 - notch for the nose, 5 - double-breasted channel. A pair of concentric circles are conventionally marked as a pair of limbs with pupils.

Using the proposed nystagmometer, the distance in millimeters between the inner edges of the restrictive rulers installed along the edges of the iris (limb) or the pupil from the nasal and temporal sides for each eye with horizontal nystagmus is measured. Substituting the obtained distance into one of the proposed formulas, you can quickly and accurately determine the amplitude of the horizontal nystagmus.

The nystagmometer proposed by the authors consists of:

1) scale marks 16 cm long (from 0 to 8 cm, starting from the left edge to the middle of the scale marks and from 0 to 8 cm from the middle to the right edge of the scale marks) and a width of 2.5 cm; division price 1 mm; material is wood;

2) an elastic tape, with which a nystagmometer is fixed on the patient's head through the back of the head;

3) restrictive rulers, preferably two for each eye, easily moving along the scale of divisions in the double-breasted channel (the length of each restrictive ruler is 4.5 cm; width 3 mm; material is aluminum);

4) nose cuts, which is fastened with a screw in the center of the scale of divisions; its length is 2 cm, width is 1.5 cm, the material is aluminum. The height of the tenderloin is changed using a screw;

5) double-breasted channel - length 15.5 cm; material - aluminum.

The use of a nystagmometer is illustrated in figure 3 and is carried out as follows.

To measure the amplitude of the horizontal nystagmus, the patient is seated on

0.5 m from the doctor examining him. During the study, the patient looks at the nose bridge of the doctor. The doctor alternately, separately for each eye, sets the inner edges of the bounding lines of the nystagmometer in such a position that the outer edge of the iris (limb) or pupil will reach the inner edge of the bounding line from the temporal side (position 3a of the bounding line 3 in Fig. 3) and the bow side (position 3b of the bounding line 3 in FIG. 3). On the scale of divisions, the distance in millimeters between the inner edges of the restrictive rulers installed along the edges of the iris (limb) or pupil from the nasal and temporal sides for each eye with horizontal nystagmus is noted. Substituting the obtained distance into one of the proposed formulas, you can quickly and accurately determine the amplitude of the horizontal nystagmus.

Example 1. A patient with a pendulum-like horizontal nystagmus.

The eyeball on both sides of the optical axis of the eye makes equal fluctuations in magnitude and the amplitude of the oscillations is equal to two amplitudes of nystagmus [Diseases of the retina, optic pathway and oculomotor apparatus. Eye Disease Guide / Ed. prof. E.Zh. Trona. - T.3 in 2 book - K.1. - M .: Medgiz, 1962. - P.349].

When the eyeball moves with nystagmus outside, the restrictive ruler (Fig. 3, position 3a) is withdrawn in the same direction to the position where the outer edge of the iris (limb) will reach the inner edge of the restrictive ruler. Then, when the eyeball moves with inward nystagmus, we repeat the same with the restrictive ruler located on the inside of the eye (Fig. 3, position 3b).

On the scale of divisions, we note the obtained distance N between the bounding bars at positions 3b and 3a in millimeters for each eye:

N = 18 mm.

Subtract the value of the horizontal diameter of the iris from it (on average 12 mm), then divide the resulting number (since it represents the range of movement of the eyeball with nystagmus in both directions) by 2 and obtain the range of movement of the eyeball with nystagmus in one direction:

(N-12): 2 = (18-12): 2 = 6: 2 = 3 mm.

Taking into account that the average distance from the center of the pupil to its edge is 1.5 mm and corresponds to the angle of deviation of the eye from the center of the pupil to its edge according to Hirschberg 15 ° [E.I. Kovalevsky, Guide to practical exercises in pediatric ophthalmology, M. , "Medicine", 1973, S.141], we obtain the formula for calculating the desired

nystagmus amplitude in degrees:

(N-12): 2: 1.5 · 15 = (N-12): 2 · 10 = (N-12) · 5 = 6 · 5 = 30 °.

Since the amplitude of the nystagmus is divided into finely spread (up to 5 °), medium-wide (from 5 ° to 15 °) and coarse (more than 15 °), we make the diagnosis: coarse pendulum-like nystagmus.

The same measurements can be carried out by setting bounding bars not at the level of the limb, but along the edge of the pupil. Since the average pupil diameter is 3 mm, the amplitude of the nystagmus is calculated in this case by the formula: (N'-3) · 5.

Example 2. A patient with a jerky horizontal nystagmus.

An eyeball with a jerky horizontal nystagmus oscillates in one of the directions - to the nose or temple; the range of motion in this case is equal to one amplitude of nystagmus [Diseases of the retina, optic pathway and oculomotor apparatus. Eye Disease Guide / Ed. prof. E.Zh. Trona. - T.3 in 2 book - K.1. - M .: Medgiz, 1962. - P.349]. Accordingly, to calculate the amplitude of nystagmus, we use the formulas:

(N-12) × 10 or (N'-3) × 10.

In this case, the value of N = 15 mm, so the amplitude of the jerky nystagmus is (15-12) · 10 = 30 °.

Thus, an inexpensive, easy to manufacture and use effective instrument for measuring the amplitude of horizontal nystagmus in the pre- and postoperative periods is proposed.

Claims (3)

1. A device for measuring the amplitude of horizontal nystagmus, including an element fixed on the patient’s head in the holder, which records the amount of displacement of the eyeball, characterized in that the scale scale is used as a holder, equipped with a nose cut and an elastic tape, and as an element that records the value displacement of the eyeball, a restrictive ruler is used, made with the ability to move on the scale of divisions. 2. The device according to claim 1, characterized in that the restrictive line is installed on the scale of divisions in the double-breasted channel. 3. The device according to claim 1 or 2, characterized in that the number of restrictive rulers is four.