LECTURE No. 13. Pathology of the oculomotor apparatus (strabismus)

Strabismus is the deviation of one or both eyes from a common point of fixation, while normal vision is disturbed (the coordinated work of both eyes).

Etiology. Allocate explicit and latent strabismus. Pathology is considered only obvious strabismus, subdivided into paralytic and concomitant. Paralytic strabismus is observed with weakness of the muscular apparatus of the eyeball, which may be due to trauma, tumor, neuroinfections, concomitant strabismus develops in childhood.

Clinical picture and diagnosis. Clinically, paralytic strabismus is manifested by the limitation or absence of movements of the squinting eye in the direction of the affected muscle, while there is a feeling of doubling of objects. With a long-term strabismus, a decrease in vision (up to blindness) of the squinting eye is possible.

Concomitant strabismus develops in childhood, while the movements of the eyeballs are preserved in full, and there is no doubling. Deviation of the eye to the nose is referred to as convergent strabismus; when the eye deviates to the temple, strabismus is considered divergent. In addition, there are deviations of the eyeball up and down, as well as a combination of horizontal and vertical deviation of the eyes.

With a constant deviation of one eye, strabismus is considered one-sided, both eyes are bilateral, alternate deviation of one or the other eye is intermittent.

If possible (depending on the age of the child), then before starting the study, it is necessary to get acquainted with the anamnesis, find out at what age the strabismus appeared. Detected from the first days of birth, it may be due to birth trauma, and signs of paresis of the oculomotor muscles may be detected. They find out whether the strabismus arose suddenly or gradually, in which the parents see the reason for its appearance. If the latter is associated with a previous eye disease, then, perhaps, a decrease in vision contributed to its development. Clarify the presence of amblyopia, signs of paralytic strabismus.

In all patients with strabismus, both the anterior segment of the eye and the fundus of the eye are carefully examined with a dilated pupil.

To decide on treatment methods, it is necessary to find out whether the patient wears glasses, at what age they were prescribed to him, and whether he wears them constantly or periodically. Determine when the last glasses were written out and which ones; Do they correct strabismus, and if so, to what extent? They clarify whether any other treatment was carried out (switching off the eye, exercises on devices, operations, etc.) and what result this gave.

After clarifying all these questions, it is necessary to examine the visual acuity of the child, first without correction, then with the existing glasses. If the vision is below 1,0 in glasses, an attempt is made to correct it.

If even with correction it was not possible to achieve full vision, this may indicate (in the absence of morphological changes in the eye) a steady decrease in vision without visible organic changes as a result of the existing strabismus of dysbinocular amblyopia.

The most convenient division of amblyopia according to severity based on the possibility of studying at school and serving in the army:

1) light 0,80,5;

2) average 0,40,3;

3) severe 0,20,05;

4) very severe 0,04 and below.

Then the nature of fixation is determined. This means that non-central fixation is accompanied by very low visual acuity.

In all patients with strabismus, in order to decide whether they need to wear glasses, clinical refraction is examined by skiascopy or refractometry 6080-1 minutes after two or three times instillation of a 0,25% solution of homatropine (0,1% solution of scopolamine in combination) into the eye followed by instillation of XNUMX% adrenaline). It should be remembered that instillation of cycloplegics deprives farsighted patients of the opportunity to accommodate excessively, therefore, in a number of patients with hypermetropia who did not wear glasses, in whom strabismus arose due to a violation of the relationship between accommodation and convergence, after turning off accommodation, the deviation of the eye disappears. In this case, this type of strabismus can be considered accommodative. Consequently, spectacle correction of ametropia (farsightedness with convergent strabismus and myopia with divergent strabismus) relieves the patient from accommodative strabismus.

In cases where the correction of ametropia does not completely eliminate the deviation of the eye, the strabismus should be considered partially accommodative.

If the strabismus does not decrease under the influence of correction, therefore, it is of a non-accommodative nature.

When examining a child, the type of strabismus is established. The eye can be deflected inward convergent strabismus (strabismus convergens), as well as outward divergent strabismus (strabismus divergens). Sometimes, along with a horizontal deviation, there is a deviation of the eye upward (strabismus sursum vergens) or downward (strabismus deorsum vergens). Vertical deviation of the eye usually indicates the presence of muscle paresis.

The next step in the study is the determination of the angle of strabismus. It is determined by various methods, the simplest of which is the Hirshberg method. In this study, the angle of deviation is judged by the position of the point reflex from the light source on the cornea of ​​the squinting eye. To obtain a reflex, an ophthalmoscope mirror is used, which is attached to the lower edge of the orbit. The patient is asked to look in a mirror. A point reflex appears on the cornea of ​​the patient's fixing eye, respectively, in the center or almost in the center of the pupil. On the squinting eye, the light reflex is detected asymmetrically to the reflex of the fixing eye (primary deflection angle). With convergent strabismus, the reflex is shifted outward from the center of the cornea, with divergent inward. Its location along the edge of the narrow pupil indicates an angle of 15°, in the center of the iris at 2530°, at the limbus 45°.

To determine the angle of the secondary deviation (the deviation of the fixing eye is more often observed), cover the fixing eye with the hand, forcing the patient to look at the ophthalmoscope mirror more often with the deviating eye. With concomitant strabismus (strabismus concomitans), the primary and secondary deviation angles are equal. The big difference in their size comes to light at paralytic strabismus (strabismus paraliticus).

A somewhat more accurate study of the angle of deviation on the perimeter. To do this, in a slightly darkened room, it is necessary to seat a sick child behind the perimeter, setting his chin in the middle of the stand. A candle is placed in the center of the horizontal arc of the perimeter, which the patient must fix with his gaze. The second candle is moved along the perimeter until its image on the cornea of ​​the squinting eye takes a position symmetrical to the image of the candle on the fixing eye. The position of the candle on the perimeter arc determines the degree of deviation of the eye; work is facilitated on the electrical perimeter.

The angle of strabismus can be determined on the syneptophore according to the scale of the device according to the position of the visual lines.

The angle of strabismus is determined both without glasses and with glasses. In children with strabismus, vision is usually monocular, rarely simultaneous.

The next step in examining a child with strabismus is to determine the functional state of the oculomotor muscles. You can judge the mobility of the eyes by asking the patient to follow the researcher's finger moving in different directions. In this study, muscle dysfunctions, mainly of horizontal action, are more clearly revealed. If the internal rectus muscle functions normally, then when the eyeball is rotated, the inner edge of the pupil reaches the level of the lacrimal openings. For convergent strabismus, due to the training of this muscle in farsighted people, as a rule, hyperfunction of the adductor is characteristic. Divergent strabismus, on the contrary, due to the weakness of the internal rectus muscle, is accompanied by some restriction of the movement of the eye inwards. When the eyeball is retracted, the outer limbus should normally reach the outer commissure of the eyelids.

An important sign of paralytic strabismus is the limitation of the movement of the eyeball towards the paralyzed muscle.

After obtaining information about the state of the sensory and motor apparatus in a patient with strabismus, as well as examining all the environments of the eye, visual acuity and visual field, a clinical diagnosis is made, for example: concomitant convergent strabismus of the right eye, non-accommodative, moderate amblyopia, far-sighted astigmatism. According to the diagnosis, treatment is prescribed.

In some cases, due to the fact that there is a significant discrepancy between the visual line and the optical axis of the eye (angle r), a false impression of convergent or divergent strabismus is created. This condition is called imaginary strabismus. With it, binocular vision is not impaired, it is not subject to treatment.

Often in children with refractive errors, latent strabismus (heterophoria) can be detected, a disorder of muscle balance, which is hidden due to the presence of binocular vision. Hidden strabismus can be detected if the urge to merge is eliminated. To do this, asking the child to fix an object located at a distance of 2530 cm from him, cover one eye with his palm.

An obstruction to binocular vision is created. Under the palm of the eye deviates inward or outward, depending on the type of heterophoria. If you quickly remove your hand, then due to the desire to merge deviations of the eye, it makes an adjusting movement. If a child has a violation of binocular vision, heterophoria is a factor conducive to the appearance of visible strabismus.

One of the types of disorders of the oculomotor apparatus is nystagmus (nystagmus). Nystagmus is called spontaneous oscillatory movements of the eyeballs. In the direction of oscillatory movements, it can be horizontal, vertical and rotatory. The range of oscillations and their frequency can be varied. With nystagmus, as a rule, visual function is significantly impaired. Nystagmus can be labyrinthine or central. In children, ocular, or fixation, nystagmus is most often observed, due to a sharp decrease in vision due to various ocular pathologies.

Differential diagnosis of concomitant and paralytic strabismus does not present significant difficulties and is carried out in the process of a thorough study of the motor function of the eyes.

Treatment and prevention. Treatment of paralytic strabismus includes the elimination of the cause that caused paresis of the oculomotor muscle, and local effects (physiotherapy).

To correct double vision, prismatic glasses are prescribed. Surgical treatment consists in strengthening the affected muscles and is used when conservative therapy is ineffective.

Treatment of concomitant strabismus includes a conservative stage (pre and postoperative) and surgical. Conservative treatment consists in restoring the normal relationship between accommodation and convergence, retinocortical connections, as well as in an attempt to improve visual acuity, the development of eye mobility.

With strabismus, if the patient has a refractive error and in the past glasses were not prescribed or do not correspond to refraction, glasses are first prescribed. When wearing correctly prescribed glasses, eye deviation disappears in 2135% of patients. With accommodative strabismus, only spectacle correction of ametropia and anisometropia is usually sufficient. In isolated cases, with accommodative strabismus, after a short wearing of glasses, binocular vision appears, but more often vision remains monocular, therefore, orthooptic treatment is necessary, which consists in joint exercise of both eyes until binocular vision appears.

If the patient, despite wearing glasses, has low vision, i.e., there is amblyopia, it is necessary to conduct a course of pleoptic treatment aimed at eliminating amblyopia before the operation. The vision of the amblyopic eye should be at least 0,3 in order to be able to start orthooptic exercises in the postoperative period. With lower visual acuity, these exercises are usually not very effective.

In young children (up to five years of age), for the treatment of amblyopia, regardless of the type of fixation, the method of direct gluing (occlusion) is used, that is, turning off the better seeing eye. Fixation disorder at this age is usually unstable. A well-seeing eye, after covering it with a sterile napkin, is sealed with a plaster. You can close the glass in glasses with dark paper and plaster, but it is best to use a special soft occluder that is fixed in glasses.

In order to train the amblyopic eye, exercises with increased visual load are simultaneously prescribed. Every three days it is necessary to remove the occluder (sticker) and inject disinfectant drops into the conjunctival sac.

Once every two weeks, visual acuity of both eyes is checked. Usually, vision in the amblyopic eye improves rapidly in the first two weeks after the start of treatment.

If the vision of the better seeing eye decreases to 0,6, the occlusion time must be reduced by 12 hours. Subsequently, the issue of the duration of daytime occlusion is decided depending on the dynamics of vision in both eyes.

Usually direct occlusion lasts for several months. When the vision of the amblyopic eye equals that of the better seeing eye, the occlusion is stopped. Gradually, they begin to open their eyes, increasing the sticking time every day in order to prevent a sudden drop in vision to the original numbers. The restored vision of the amblyopic eye is often accompanied by the transition of monolateral strabismus to alternating (intermittent), which further prevents the recurrence of amblyopia.

In children over five to six years of age, if the amblyopic eye is incorrectly fixed, switching off the better seeing eye is not recommended, as this leads to strengthening of the incorrect fixation. Sometimes in such cases the amblyopic eye is switched off (this is the so-called reverse occlusion) for a month and a half. During this period, in some cases, correct fixation is restored.

In school-age children, both with central and with incorrect fixation, treatment is carried out according to the method of E. S. Avetisov, which consists in irritating the central fossa of the retina with the light of a flash lamp inserted into the optical system of a large ophthalmoscope. The course of treatment is 2530 lessons.

Surgical treatment is carried out taking into account the functional ability of the oculomotor muscles. With convergent strabismus with a large deviation of the eye, Kovalevsky tenomyoplasty is preferable in order to lengthen the muscle, with smaller angles of recession of the internal rectus muscle. In the presence of alternating strabismus, the same type of operation should be performed simultaneously on both eyes.

If the operation on the internal rectus muscles is not very effective, intervention on the external resection (tenorrhaphy), prorraphy is possible. With divergent strabismus, due to weakness of the internal rectus muscle, as a rule, tenorrhaphy of the internal rectus muscle or a dosed partial resection of it with transplantation closer to the limbus is performed.

In the postoperative period, the entire complex of treatment is again carried out, aimed at improving vision, eliminating residual deviation, restoring normal retinal correspondence, and developing fusion (image fusion).

With normal retinal correspondence, classes to develop binocular vision are carried out at home using a mirror stereoscope. Treatment should be long-term and regular (one to two years) until binocular vision appears and evidence of the patient’s recovery.

If, during the examination, clear signs of paralysis or paresis of one of the muscles are detected in the patient (limited mobility of the eyeball, diplopia), it is necessary to subject him to a thorough neurological examination. The question of surgical intervention is raised in such cases only after long-term treatment of the underlying disease and is agreed upon with a neurologist. Treatment of strabismus begins at three to four years of age and should end in preschool age.

Prevention of strabismus consists of early determination of clinical refraction (up to one or two years), checking visual acuity and spectacle correction of ametropia, observing sanitary and hygienic conditions for visual work, and eliminating pathological changes in the eye.

Author: Shilnikov L.V.

<< Back: Trachoma

>> Forward: General issues of vascular tract pathology (Questioning the patient. External examination of the eye and examination of the cornea. Examination of the iris of the pupil and lens. Examination of the fundus and ophthalmoscopy. Detection of inflammatory processes. Detection of congenital anomalies and neoplasms)

We recommend interesting articles Section Lecture notes, cheat sheets:

▪ Microbiology. Crib

▪ Psychology. Crib

▪ Investments. Lecture notes

See other articles Section Lecture notes, cheat sheets.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

The existence of an entropy rule for quantum entanglement has been proven 09.05.2024

Quantum mechanics continues to amaze us with its mysterious phenomena and unexpected discoveries. Recently, Bartosz Regula from the RIKEN Center for Quantum Computing and Ludovico Lamy from the University of Amsterdam presented a new discovery that concerns quantum entanglement and its relation to entropy. Quantum entanglement plays an important role in modern quantum information science and technology. However, the complexity of its structure makes understanding and managing it challenging. Regulus and Lamy's discovery shows that quantum entanglement follows an entropy rule similar to that for classical systems. This discovery opens new perspectives in the field of quantum information science and technology, deepening our understanding of quantum entanglement and its connection to thermodynamics. The results of the study indicate the possibility of reversibility of entanglement transformations, which could greatly simplify their use in various quantum technologies. Opening a new rule ... >>

Mini air conditioner Sony Reon Pocket 5 09.05.2024

Summer is a time for relaxation and travel, but often the heat can turn this time into an unbearable torment. Meet a new product from Sony - the Reon Pocket 5 mini-air conditioner, which promises to make summer more comfortable for its users. Sony has introduced a unique device - the Reon Pocket 5 mini-conditioner, which provides body cooling on hot days. With it, users can enjoy coolness anytime, anywhere by simply wearing it around their neck. This mini air conditioner is equipped with automatic adjustment of operating modes, as well as temperature and humidity sensors. Thanks to innovative technologies, Reon Pocket 5 adjusts its operation depending on the user's activity and environmental conditions. Users can easily adjust the temperature using a dedicated mobile app connected via Bluetooth. Additionally, specially designed T-shirts and shorts are available for convenience, to which a mini air conditioner can be attached. The device can oh ... >>

Energy from space for Starship 08.05.2024

Producing solar energy in space is becoming more feasible with the advent of new technologies and the development of space programs. The head of the startup Virtus Solis shared his vision of using SpaceX's Starship to create orbital power plants capable of powering the Earth. Startup Virtus Solis has unveiled an ambitious project to create orbital power plants using SpaceX's Starship. This idea could significantly change the field of solar energy production, making it more accessible and cheaper. The core of the startup's plan is to reduce the cost of launching satellites into space using Starship. This technological breakthrough is expected to make solar energy production in space more competitive with traditional energy sources. Virtual Solis plans to build large photovoltaic panels in orbit, using Starship to deliver the necessary equipment. However, one of the key challenges ... >>

Random news from the Archive China begins research into 5G communications 16.01.2016 The Ministry of Industry and Information Technology of China has announced the start of research into fifth generation mobile networks (5G). Currently, the project is at an experimental stage: it will last three years - from 2016 to 2018. After that, the pilot operation of new generation networks will begin. Participants of the telecommunications market are planning to demonstrate the capabilities of 5G services at the upcoming Winter Olympic Games, which will be held in February 2018 in Pyeongchang, the Republic of Korea. It is assumed that the first commercial 5G networks will start working, including in China, approximately in 2020. They have a maximum data transfer rate of 20 Gbps. Recently, the Japanese corporation NTT DOCOMO announced the first successful test of a 5G network in a commercial building. Testing was carried out at the Roppongi Hills high-rise complex in Tokyo. The signal was transmitted using millimeter waves in the 70 GHz band, and the communication channel capacity exceeded 2 Gbps. Giants such as Nokia Networks, Samsung, Ericsson, Fujitsu, Huawei and others are involved in the development of 5G technologies.

Other interesting news:

▪ The hardest alloy

▪ Rarest eye color revealed

▪ superMHL/HDMI 2.0 port processor

▪ New digital signal processors based on 90nm technology

▪ New wireless power transmission system

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Lighting. Article selection

▪ article Germany above all. Popular expression

▪ article What were Cinderella's shoes made of? Detailed answer

▪ article Execution of copy offset processes. Standard instruction on labor protection

▪ article Shortened antenna for a range of 160 meters. Encyclopedia of radio electronics and electrical engineering

▪ article Two-stroke reduced power inverter, 190-230/6-27 volts 6 amps. Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages ​​of this page

Arabic	Hebrew	Polish
Bengali	Hindi	Portuguese
Chinese	Italian	Spanish
English	Japanese	Turkish
French	Korean	Ukrainian
German	Malay	Vietnamese

Home page | Library | Articles | Website map | Site Reviews

www.diagram.com.ua
2000-2024