RU2738667C1 - Method for assessing binocular vision in strabismus based on chromostereopsis - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention relates to ophthalmology and is intended for assessing binocular vision based on chromostereopsis in patients with strabismus. Examination is carried out in a room with illumination of at least 500 lx in conditions of complete prismatic angle of strabismus compensation. On the monitor screen, 16 test images are successively presented, each of which consists of a square and a circle located inside it and has color characteristics with varying ratio of red and blue components from identical to as different as possible. Ability to stereotype by the patient's ability to determine the relative position of the figures in the sagittal plane is evaluated. Color characteristics of the square and the circle for each test image are calculated by the RGB system from R 127.5, G 0, B 127.5 to R 0, G 0, B 255 - for the blue square, R 255, G 0, B 0 - for red circle, and in each next test image ratio of red and blue components for each figure is changed by 8.5.

EFFECT: invention provides an assessment of the degree of stereoscopic disorder with prescribing a corresponding correction with a therapeutic purpose and possibility of using the method in patients with color vision disorders, as well as simple and easy to use.

1 cl, 1 tbl, 1 dwg

Description

The present invention relates to ophthalmology and is intended for assessing stereovision based on chromostereopsis in patients with strabismus.

Chromostereopsis (CS) is a visual phenomenon consisting in the perception of depth displacement of objects of different colors, objectively located at the same distance from the observer.

The main causes of natural CS (occurring without the use of spherical or prismatic optics) are transverse chromatic aberration created by the optical structures of the eye and the displacement of the fovea with respect to the posterior pole of the eye. Most (about 80%) people have a positive CS, in which red objects on a dark background appear closer than blue or green. Meanwhile, in about 20% of people, cholesterol has the opposite sign or is absent. This phenomenon is explained by the fact that CS is a multicomponent effect, depending on: individual characteristics of the anatomical structure of the eyes; illumination level; dynamics of the width, shape and asymmetry of the pupils (Rozhkova GI, Gracheva MA Natural chromostereopsis: causes and individual variations of binocular spatial color effects. Review. // Sensory systems. - 2014. - No. 1. - P. 3- 14).

The reason for spectacle CS (which occurs when using prisms or spherical optics with a prismatic component) is the different degree of refraction of short-wave and long-wave light rays. In this case, the displacement on the retina of the projections of images of red and blue objects is equivalent to binocular disparity, which creates a stereo effect. ChS caused by the prismatic effect depends on the strength of the prisms, the interpupillary distance and the difference in refractive indices for radiation with different wavelengths (Rychkova S.I., Bolshakov A.S., Gracheva M.A., Rozhkova G.I. // Sensory systems. - 2014. - No. 1. - S. 72-80).

Individual features and ambiguity of spatial sensations in natural CS complicate its practical application. Meanwhile, the artificial CS, created by prisms, significantly surpasses the natural effects and provides more unambiguous spatial sensations that have common patterns in different people. The glasses "ChromaDepth glasses" based on this principle are currently widely used for visualization of educational and scientific information, as well as in the creation of educational games (Steenblik RA Stereoscopic process and apparatus using different deviations of different colors // US Patents No. 4-717 -239 (1988); Steenblik RA Stereoscopic process and apparatus using different deviations of different colors // US Patents No. 5-002-364 (1991)). Meanwhile, for the study of stereovision in ophthalmic practice, this technology has not been used until now, since it provides for the presence of orthotropy (normal position of the visual axes) and a good state of binocular visual functions in the user.

There is a method that allows to study stereovision in patients with a strabismus angle using a synoptophore, in the set of test images of which, along with simple figures for the study of binocular vision, stereostimuli are also provided (Kashchenko T.P. Binocular visual system with concomitant strabismus: author. dis. ... doctor of medical sciences 14.01.07 / T.P. Kashchenko. - M., 1978. - 278 p.). Due to the ability to install the tubes of the device with test images at the strabismus angle (so that the stereo images are projected onto the central zone of the retina of both eyes), the device makes it possible to study stereo vision in conditions of mechanical separation of visual fields. Meanwhile, these observation conditions are far from natural. The projection of images on the central zones of the retina of both eyes in the closest to natural observation conditions is provided by prism compensation of the strabismus angle (Kashchenko T.P. The use of prismatic lenses in ophthalmology / T.P. Kashchenko, S.G. Chernysheva, Yu.Z. Rosenblum, A.E. Petrenko // Bulletin of Optometry. - 2005. - No. 31. - P. 22-25.).

In modern ophthalmology, prismatic correction is used in the following directions - to measure and compensate for the angle of strabismus, to compensate for weakened or insufficient convergence for visual work at close range (especially in patients with low vision), as well as for visual exercises aimed at developing fusional ability ( Utekhin YA, Tsameryan AP Method of prevention and stabilization of myopia using bifocal spheroprismatic glasses (BSPO) // International symposium "Myopia". Pathogenesis, prevention of progression and complications. M .: 1990. P. 109, 110; Plisov I.L., Belousova K.A., Bikbulatova D.R. et al. Algorithm of orthoptic treatment of paralytic strabismus in conditions of rigid haploscopy and prismatic correction // Ophthalmosurgery. - 2012. - No. 1. - P. 22-25; Kashchenko T.P., Chernysheva S.G., Rosenblum Yu.Z. et al. Application of prismatic lenses in ophthalmology // Bulletin of optometry. - 2005. - No. 31. - P. 22-25; Kurochkin V.N. ., Terekhova T.V., Glumskova Yu.D. and other Application of Fresnel prisms in the complex treatment of concomitant strabismus // Ophthalmology. - 2018 .-- 15 (2). - S. 98-105).

Meanwhile, the possibility of using prisms in the diagnosis of stereovision in strabismus has not yet been considered.

The closest analogue of the proposed method is a method for assessing CS using prisms and two light sources (red and blue), including strabismus (Rychkova S.I., Bolshakov A.S., Gracheva M.A., Rozhkova G.I. Spectacled chromostereopsis in people with different indicators of natural chromostereopsis // Sensory systems, 2014. - No. 1. - P. 72-80). This method involves conducting research in a completely darkened room. The test objects are point light sources - LEDs with red and blue radiation, the brightness of which is equalized using neutral filters. The blue LED is fixed at a distance of 2.8 m from the subject. The red LED can be moved in depth, but in the initial position it is set at the same distance from the eyes as the blue one. The distance between the LEDs in the frontal plane is 4 cm. During the measurements, acrylic prisms from Luneau Ophtalmologie are used, which are inserted into a trial spectacle frame. The difference in the distance from the red and blue LEDs to the subject is assessed by shifting the red test object in depth until the subject has an equal distance of both LEDs. Note the distance between the red and blue LEDs (in cm). The study is carried out with prisms of various strengths, from 2.0 to 10.0 prism diopters (prDptr). During a series of measurements, the strength of the prisms and their orientation (base to nose or base to temple) are changed randomly. If the subject has ametropia, the optimal correction optics are additionally used. The disadvantages of this method are: 1) the need to use a completely darkened room, which creates technical difficulties during measurements; 2) impossibility to change the spectral characteristics of the radiation used during the study.

The objective of the present invention is to further develop and improve the method for assessing the ability to stereovision based on CS.

The technical result of the proposed method is the ability to assess the degree of impairment of stereovision with the appointment of appropriate correction for therapeutic purposes and the possibility of using the method in patients with color vision disorders. An additional technical result is simplicity and ease of use.

The technical result is achieved by presenting on the monitor screen in natural illumination conditions the developed test image containing elements with different spectral characteristics and a changing ratio of red and blue components from identical to the most different and assessing the ability to stereoscopic perception by the patient's ability to determine the relative position of figures along the sagittal plane ...

There are 16 test images (created in the Corel program), each of which consists of a square and a circle located inside it (Fig. 1). The color characteristics of the square and circle for each test image can be calculated using the RGB system in such a way that in the test image (No. 1) the color of both figures is identical (a square and a purple circle with characteristics R 127.5, G 0, B 127.5 ), in each next image the ratio of the red and blue components for each figure changes by 8.5 and in the last image (No. 16) the colors of the square and the circle are maximally different (R О, G О, В 255 - for a blue square, R 255, G 0, B 0 - for the red circle). Data on the color characteristics of all images are presented in the table (Table 1). Thus, the patient's task is to determine and name for each test image presented on the monitor screen - is the circle in depth closer than a square, further than a square, or both figures seem to be located in the same plane.

For patients with strabismus, before the study, prisms are selected that fully compensate for the angle of strabismus, and the study is carried out only under such conditions.

The method is carried out as follows.

In a patient with strabismus, the study is carried out in a room with an illumination of at least 500 lux in conditions of full prism compensation of the strabismus angle. 16 test images are sequentially presented on the monitor screen, each of which consists of a square and a circle located inside it, and has color characteristics with a varying ratio of red and blue components from identical to maximally different. The ability to stereospeak is assessed by the patient's ability to determine the relative position of the figures in depth (in the sagittal plane).

The color characteristics of the square and circle for each test image can be calculated using the RGB system from R 127.5, G O, B 127.5 to R O, G O, B 255 - for a blue square, R 255, G O, B 0 - for the red circle, and in each subsequent test image, the ratio of red and blue components for each figure changes by 8.5.

Example 1.

Patient V.I., age 12 years.

Diagnosis: Concomitant unstable convergent monolateral strabismus of the left eye. Moderate hyperopia in both eyes. Dysbinocular amblyopia of weak degree of the left eye.

Visual acuity: vis OD = 0.6 sph (+) 2.5D = 1.0; vis OS = 0.5 sph (+) 3.0D = 0.8. Refraction under cycloplegia (midriacil 1% threefold): OD = sph (+) 3.0D; OS = sph (+) 3.5D. Strabismus angle according to Hirshberg with and without glasses from 0 ° to (+) 5 ° OS, cvt (+) 7 °. In conditions of optimal spectacle correction, the strabismus angle is fully compensated by the prism 14.0 prD OS ax 180 °, the base to the temple. In the study with a four-point color test, the nature of vision is unstable binocular. In the study on the synoptophore, the normal correspondence of the retinas is unstable (alternating with a functional suppression scotoma) at an objective strabismus angle (+) 7 ° without fusion reserves. In the study with the Lang test and the Fly test, stereo vision is absent.

A study was carried out to assess the ability to stereovision based on chromostepsis using the developed method: in a room with an illumination of at least 500 lx in conditions first without prism compensation, and then in conditions of full prism compensation of the strabismus angle, 16 test images were sequentially presented on the monitor screen (Fig. one). The child was asked to evaluate the relative position of the circle and the square in all 16 images. The results showed the following:

1) No prism compensation - XC is absent with all 16 tests. The obtained result testified to the absence of stereo vision under normal observation conditions.

2) With a prism 14.0 prD OS ax 180 °, base to the temple - negative cholesterol with tests No. 12-16.

The results obtained indicate a reduced ability to stereovision, despite the prism compensation of the strabismus angle, which requires functional correction of stereovision.

Example 2.

Patient Z.M., 11 years old.

Diagnosis: Concomitant unstable divergent monolateral strabismus of the right eye. Myopia of the middle degree of the right eye, weak degree of the left eye. Dysbinocular amblyopia of weak degree of the right eye.

Visual acuity: vis OD = 0.2 sph (-) 4.5D = 0.8; vis OS = 0.5 sph (-) 1.0D = 1.0. Refraction under cycloplegia (midriacil 1% threefold): OD = sph (-) 5.0D; OS = sph (-) 1.5D. Strabismus angle according to Hirshberg with and without glasses from 0 ° to (-) 5 ° OD, cvt (-) 10 °. In conditions of optimal spectacle correction, the strabismus angle is fully compensated by the prism 16.0 prD OS ax 180 °, base to the nose. In the study with a four-point color test, the nature of vision is unstable binocular. In the study on the synoptophore - normal correspondence of the retinas at an objective angle of strabismus (-) 7 ° without fusion reserves. In the study with the Lang test and the Fly test, stereo vision is absent.

A study was carried out to assess the ability to stereovision based on chromostepsis using the developed method: in a room with an illumination of at least 500 lx in conditions first without prism compensation, and then in conditions of full prism compensation of the strabismus angle, 16 test images were sequentially presented on the monitor screen (Fig. . one). The child was asked to evaluate the relative position of the circle and the square in all 16 images. The results showed the following:

1) Without prisms - CS is absent with all tests, which indicates the absence of stereo vision under normal observation conditions.

2) With a prism of 16.0 prD OD ax 180 °, base to the nose - positive cholesterol with tests No. 13-16.

These results demonstrate a decrease in the ability to stereovision, despite the prism compensation of the strabismus angle, which requires its functional correction.

Example 3.

Patient M.D., age 14.

Diagnosis: Concomitant permanent convergent monolateral strabismus of the right eye. Hyperopia of the middle right eye, weak degree of the left eye. Dysbinocular amblyopia of weak degree of the right eye.

Visual acuity: vis OD = 0.2 sph (+) 3.5D = 0.5; vis OS = 0.5 sph (+) 1.0D = 0.9. Refraction under cycloplegia (midriacil 1% threefold): OD = sph (+) 4.0D; OS = sph (+) 1.5D. The Hirshberg strabismus angle with and without glasses is from (+) 5 ° OD, cvt (+) 5 °. In conditions of optimal spectacle correction, the strabismus angle is fully compensated by the prism 10.0 prD OD ax 180 °, base to the temple. In the study with a four-point color test, the nature of vision is monocular. In the study on the synoptophore - functional scotoma suppression at an objective angle of strabismus (+) 5 °. In the study with the Lang test and the Fly test, stereo vision is absent. A study was carried out to assess the ability to stereovision based on chromostepsis using the developed method: in a room with an illumination of at least 500 lx in conditions, first without prism compensation, and then in conditions of full prism compensation of the strabismus angle, 16 test images were sequentially presented on the monitor screen (Fig. one). The child was asked to evaluate the relative position of the circle and the square in all 16 images. The results showed the following:

1) Without prisms - XC is absent with all tests. The result indicates that the patient does not have stereo vision under normal observation conditions.

2) With a prism of 10.0 prD OD ax 180 ° with a base to the temple, compensating for the strabismus angle, stereovision is also absent in conditions of prism compensation for the strabismus angle.

The results in this case indicate the need for functional treatment aimed at developing stereovision.

Example 4.

Patient D.P., age 12 years.

Diagnosis: Concomitant operated divergent monolateral strabismus of the left eye. Mild myopia in both eyes. Dysbinocular amblyopia of weak degree of the left eye.

Visual acuity: vis OD = 0.7 sph (-) 1.0D = 1.0; vis OS = 0.5 sph (-) 2.5D = 0.7. Refraction under cycloplegia (midriacil 1% threefold): OD = sph (-) 1.5D; OS = sph (-) 3.0D. The Hirshberg strabismus angle with and without glasses (-) 7 ° OS, cvt (-) 10 °. In conditions of optimal spectacle correction, the strabismus angle is fully compensated by the prism 19.0 prD OS ax 180 °, base to the nose. In the study with a four-point color test, the nature of vision is unstable binocular. In the study on the synoptophore - a functional suppression scotoma at an objective angle (-) 10 °. A study was carried out to assess the ability to stereovision based on chromostepsis using the developed method: in a room with an illumination of at least 500 lx in conditions, first without prism compensation, and then in conditions of complete prism compensation of the strabismus angle, 16 test images were sequentially presented on the monitor screen. The child was asked to evaluate the relative position of the circle and the square in all 16 images. The results showed the following:

1) without prisms - XC is absent with all tests. The result indicates that the patient does not have stereo vision under normal observation conditions.

2) with a prism of 19.0 prD OD ax 180 ° base to the nose, compensating for the strabismus angle, stereovision is also absent in conditions of prism compensation for the strabismus angle.

Functional treatment is needed to develop stereovision.

Thus, the proposed method for assessing the ability to stereovision based on CS allows patients with strabismus to assess the ability to stereospection in conditions of prism compensation of the strabismus angle without additional separation of visual fields.In addition, the method allows us to assess the severity of chromostereopsis, which must be taken into account when prescribing prismatic correction. with a therapeutic purpose. The advantages of this method, along with observation conditions as close as possible to natural ones, include the absence of the need to use paired images. This method can be used in patients with color vision impairments, since the stereo effect is created due to the relative displacement of projections of objects of different colors on the retina, created by prisms, and does not depend on the features of the retinal cone apparatus and other anatomical and physiological structures involved in color analysis.

Claims (2)

1. A method for assessing the ability to stereoscopic perception in strabismus based on chromostereopsis, characterized in that the study is carried out in a room with an illumination of at least 500 lx under conditions of full prism compensation of the strabismus angle, while 16 test images are presented on the monitor screen, each of which consists from a square and a circle located inside it and has color characteristics with a varying ratio of red and blue components from identical to maximally different and assess the ability to stereoscience by the patient's ability to determine the relative position of figures in the sagittal plane. 2. The method according to claim 1, characterized in that the color characteristics of the square and circle for each test image are calculated according to the RGB system from R 127.5, G 0, B 127.5 to R 0, G 0, B 255 - for blue square, R 255, G 0, B 0 - for the red circle, and in each next test image the ratio of red and blue components for each figure changes by 8.5.

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