Ultrasound examination of the anterior-posterior size of the eyeball. Measuring the length of the eye Anterior posterior axis of the eye has decreased

Ultrasound examination (ultrasound) completes the ophthalmological examination of the patient because it is contact. And any microdamage to the cornea can distort the readings of autorefractometry or aberrometry.

A-scanning (ultrasound biometrics) determines the size of the anterior chamber of the eye, the thickness of the lens and the anteroposterior segment (APO - anteroposterior eye size) with an accuracy of hundredths of a millimeter. With myopia, the eye enlarges, which is fixed by the apparatus. PZO is used even when identifying the degree of progression of myopia. PZO is normally 24 mm (Fig. 15).

Rice. 15. Dimensions eyeball. The length of the anteroposterior segment of a normal eyeball practically coincides with the diameter of a five-ruble coin

B-scan is a conventional two-dimensional ultrasound of the eye. Retinal detachment can be diagnosed (urgent surgery is needed, laser correction in best case delayed for a long time), destruction of the vitreous body, intraocular tumors, etc.

Pachymetry. Measurement of corneal thickness. The very indicator that most often supplies contraindications for laser correction. If the cornea is too thin, correction is often not possible. The normal thickness of the cornea at the center is 500–550 micrometers (~0.5 mm). Now there are not only ultrasonic, but also optical pachymeters that measure the thickness of the cornea without touching it.

Conclusion

All of the above are only the main stages of an ophthalmological examination. There may be much more research and apparatus, especially if you find any eye diseases. There are optional but desirable examinations that I decided not to mention here (such as determining the leading eye, deviations, etc.).

After the end of the ophthalmological examination, the doctor makes a diagnosis and answers your questions, the main one of which is: “Can I do laser correction?” It is extremely rare that situations arise in which laser correction is necessary for medical reasons (for example, with a large difference in the “pluses” or “minuses” between the eyes).

Features of filling out a consulting opinion

After the examination, the patient is given a consultation report, which reflects the main results, diagnosis and recommendations. Sometimes very briefly, sometimes an impressive work on several sheets, including various printouts and photographs. Who cares. Volume doesn't mean anything here. However, get a little useful information from it is possible. I'll give you an example.

Advisory opinion no. ....

Ivanov Ivan Ivanovich. Date of birth 01/01/1980.

Examined in the clinic "Z" 01/01/2008.

Complains of poor distance vision since the age of 12. The last five years of progression of myopia does not note, which is confirmed by the data from the outpatient card. Preventive laser coagulation of the retina was performed on both eyes in 2007. Wears soft contact lenses daily for the last 3 years. I removed them for the last time 7 days ago. Hepatitis, tuberculosis, other infectious and general somatic diseases, drug allergy denies.

For a narrow pupil:

OD sph –8.17 cyl –0.53ax 178°

OS sph –8.47 cyl –0.58ax 172°

In conditions of cycloplegia (on a wide pupil):

OD sph –7.63 cyl –0.45 ax 177°

OS sph –8.13 cyl –0.44ax 174°

Visual acuity.

Ultrasound of the eye (or ophthalmoechography) is a safe, simple, painless and highly informative method for examining the structures of the eye, which allows them to be imaged on a computer monitor as a result of the reflection of high-frequency ultrasonic waves from the tissues of the eye. If such a study is supplemented by the use of color Doppler mapping of the vessels of the eye (or color doppler), then the specialist can also assess the state of blood flow in them.

In this article, we will provide information about the essence of the method and its varieties, indications, contraindications, methods for preparing and conducting an ultrasound of the eye. This data will help you understand the principle of this diagnostic method, and you will be able to ask the ophthalmologist questions that arise.

An ultrasound of the eye can be prescribed both to detect many ophthalmic pathologies (even on initial stages their development), and to assess the state of the structures of the eye after performing surgical operations (for example, after replacing the lens). In addition, this procedure makes it possible to monitor the dynamics of the development of chronic ophthalmic diseases.

The essence and varieties of the method

Ultrasound of the eye is a simple and at the same time highly informative method for diagnosing eye diseases.

The principle of ophthalmic echography is based on the ability of the ultrasonic waves emitted by the sensor to be reflected from the tissues of the organ and converted into an image displayed on a computer monitor. Thanks to this, the doctor can receive the following information about the eyeball:

measure the size of the eyeball as a whole;
evaluate the length of the vitreous body;
measure the thickness of the inner membranes and the lens;
assess the length and condition of retrobulbar tissues;
determine the size or detect tumors of the ciliary department;
study the parameters of the retina and choroid;
identify and evaluate characteristics (if it is impossible to determine these changes in time);
differentiate primary retinal detachment from secondary, which was caused by an increase in tumors of the choroid;
detect foreign bodies in the eyeball;
determine the presence of opacities, exudate or blood clots in the vitreous body;
reveal .

Such a study can be performed even with clouding of the optical media of the eye, which can make it difficult to diagnose using other methods of ophthalmological examination.

Usually, ophthalmic echography is supplemented by Doppler sonography, which allows assessing the condition and patency of the vessels of the eyeball, the speed and direction of blood flow in them. This part of the study makes it possible to detect abnormalities in blood circulation even at the initial stages.

For ultrasound of the eye, the following varieties of this technique can be used:

One-dimensional echography (or mode A). This research method is used to determine the size of the eye or its individual structures and assess the state of the orbits. When carrying out this technique, a solution is instilled into the patient's eye and the device's sensor is installed directly on the eyeball. As a result of the examination, a graph is obtained that displays the parameters of the eye necessary for diagnosis.
2D echography (or mode B). This method allows you to get a two-dimensional picture and characteristics of the structure of the internal structures of the eyeball. It does not require special preparation of the eye, and the sensor of the ultrasound machine is installed on the closed eyelid of the subject. The study itself takes no more than 15 minutes.
Combination of modes A and B. This combination of the above methods makes it possible to obtain a more detailed picture of the state of the eyeball and increases the information content of the diagnosis.
Ultrasonic biomicroscopy. This method involves digital processing of the echo signals received by the apparatus. As a result, the quality of the image displayed on the monitor is increased several times.

Doppler examination of the vessels of the eye is performed according to the following methods:

3D echography. This method of research makes it possible to obtain a three-dimensional image of the structures of the eye and its vessels. Some modern devices allow you to get a picture in real time.
Power Doppler. Thanks to this technique, a specialist can study the state of the vessels and evaluate the amplitude and velocity values of blood flow in them.
Pulsed wave dopplerography. This method of research analyzes the noise that occurs during blood flow. As a result, the doctor can more accurately assess its speed and direction.

When conducting ultrasound duplex scanning, all the possibilities of both conventional ultrasound and Doppler studies are combined. This method of examination simultaneously provides data not only on the size and structure of the eye, but also on the state of its vessels.

Indications

Ultrasound of the eye is one of the diagnostic methods recommended for patients with myopia or hyperopia.

Ultrasound of the eye may be prescribed in the following cases:

high degrees or farsightedness;
glaucoma;
retinal disinsertion;
pathology of the eye muscles;
suspicion of a foreign body;
diseases of the optic nerve;
trauma;
vascular pathologies of the eyes;
congenital anomalies in the structure of the organs of vision;
chronic diseases that can lead to the appearance of ophthalmic pathologies: kidney diseases accompanied by hypertension;
monitoring the effectiveness of treatment of oncological eye pathologies;
monitoring the effectiveness of therapy for vascular changes in the eyeball;
evaluation of the effectiveness of the performed ophthalmic operations.

Doppler ultrasound of the eye is indicated for the following pathologies:

spasm or obstruction of the retinal artery;
thrombosis of the eye veins;
narrowing of the carotid artery, leading to impaired blood flow in the ophthalmic arteries.

Contraindications

Ultrasound of the eye is an absolutely safe procedure and has no contraindications.

Patient preparation

Ophthalmic echography does not require special preparation of the patient. When prescribing it, the doctor must explain to the patient the essence and necessity of performing this diagnostic study. Particular attention is paid to the psychological preparation of young children - the child must know that this procedure will not cause him pain, and behave correctly during the ultrasound scan.

If it is necessary to use mode A during the study, before the examination, the doctor must clarify with the patient the data on the presence of an allergic reaction to local anesthetics and choose a drug that is safe for the patient.

Ultrasound of the eye can be performed both in a clinic and in a hospital. The patient should take with him a referral to the study and the results of previously performed ophthalmosonography. Women should not use eye make-up before the procedure, as a gel will be applied to the upper eyelid during the examination.

How the study is done

Ophthalmoechography is performed in a specially equipped room as follows:

The patient sits in a chair in front of the doctor.
If mode A is used for the examination, then a local anesthetic solution is instilled into the patient's eye. After the start of its action, the doctor carefully installs the sensor of the apparatus directly on the surface of the eyeball and moves it as necessary.
If the study is performed in mode B or dopplerography is performed, then anesthetic drops are not used. The patient closes his eyes and the gel is applied to his upper eyelids. The doctor places the sensor on the patient's eyelid and performs the study for 10-15 minutes. After that, the gel is removed from the eyelids with a napkin.

After the procedure, the ultrasound specialist draws up a conclusion and hands it over to the patient or sends it to the attending physician.

Norm indicators

The interpretation of the results of ophthalmic echography is carried out by a specialist in ultrasound diagnostics and the attending physician of the patient. For this, the obtained results are compared with the indicators of the norm:

vitreous body– transparent and has no inclusions;
the volume of the vitreous body is about 4 ml;
anterior rear axle vitreous body - about 16.5 mm;
the lens is transparent, invisible, its posterior capsule is clearly visible;
eye axis length - 22.4-27.3 mm;
thickness of inner shells - 0.7-1 mm;
the width of the hypoechoic structure of the optic nerve is 2-2.5 mm;
refractive power of the eye with emmetropia - 52.6-64.21 D.

Which doctor to contact

An ultrasound of the eye may be ordered by an ophthalmologist. For some chronic diseases that cause changes in the state of the eyeball and fundus, such a procedure may be recommended by doctors of other specializations: an internist, neuropathologist, nephrologist or cardiologist.

Ultrasound of the eye is a highly informative, non-invasive, safe, painless and easy-to-perform diagnostic procedure that helps to make the correct diagnosis in many ophthalmic pathologies. If necessary, this study can be repeated many times and does not require any breaks. For an ultrasound of the eye, the patient does not need to conduct special training and there are no contraindications and age restrictions for the appointment of such an examination.

Thanks to the research, scientists have found that the trigger for development is an increase intraocular pressure to a level above the target. Intraocular pressure is an important physiological constant of the eye. It is regulated by several mechanisms. On the this indicator influenced by some anatomical and physiological factors. The main ones are the volume of the eyeball and the size of the anterior-posterior axis of the eye. Studies conducted in recent years have led to the conclusion that glaucoma can develop as a result of a change in the biomechanical stability of the connective tissue structures of the fibrous capsule of the eye, and not just the area of the optic nerve head.

In ophthalmological studies, the following diagnostic methods are used:

tonometry;
tonography according to Nesterov and elastotonometry;

In young children, the upper limit of the norm of intraocular pressure may be a manifestation of a violation of the outflow of intraocular fluid. The length of the anteroposterior axis of the eyeball increases not only due to the accumulation of intraocular fluid and disturbance of the hemohydrodynamic processes of the organ of vision, but also due to the dynamics of pathological growth of the eye with age and degree. For the diagnosis of congenital glaucoma, it is necessary to use data from such examinations as echobiometry, gonioscopy, measurement of intraocular pressure. This should take into account the rigidity of the fibrous membrane of the eye and incipient glaucomatous optic neuropathy.

At the ninth week of intrauterine development, the sagittal size is 1 mm, by 12 weeks it increases to an average of 5.1 mm.

The total length of the eye of a premature infant (25-37 weeks after conception) increases linearly from 12.6 to 16.2 mm. The results of measurements according to a more recent study are shown in the table below.

Results of measurements of the eye of a newborn with ultrasound:
1. The average depth of the anterior chamber (including the cornea) is 2.6 mm (2.4-2.9 mm).
2. The average thickness of the lens is 3.6 mm (3.4-3.9 mm).
3. The average length of the vitreous body is 10.4 mm (8.9-11.2 mm).
4. The total length of the eye of a newborn is 16.6 mm (15.3-17.6 mm).

Postnatal growth of the emmetropic eye can be divided into three stages:
1. The phase of rapid postnatal growth, when during the first 18 months of life the length of the eye increases by 3.7-3.8 mm.
2. Slower phase, at the age of two to five years, the length of the eye increases by 1.1-1.2 mm.
3. Slow juvenile phase, which lasts until the age of 13 years, the length of the eye increases by another 1.3-1.4 mm, after which the growth of the eye in length is minimal.

Anterior-posterior size and growth rate of the eye from 20 weeks of gestation to three years of age.

Relationships between different structures of the eye during growth.
results ultrasound examination.

Antero-posterior eye size in boys (mm).

Dimensions of the oculomotor muscles and sclera

In the first six months of life, the highest growth rate of the eye is noted. All its dimensions are increasing. At birth, the size of the cornea and iris is approximately 80% of that of an adult cornea and iris.

The posterior segment, on the contrary, grows to a greater extent in the postnatal period. Therefore, this creates additional difficulties in predicting the results. surgical treatment strabismus in very young children.

The thickness of the sclera at the age of 6, 9 and 20 months is 0.45 mm, as in the eyes of an adult.

Ultrasound of the eyes is an additional technique in ophthalmology, which has high accuracy in detecting hemorrhages and assessing the anteroposterior axis of the eye. The latter indicator is necessary to detect the progression of myopia in children and adults. There are other areas of application of the technique. This diagnostic method is distinguished by the simplicity of the procedure, the lack of additional preparation and the speed of the examination. Ultrasound is performed using universal and specialized ultrasonic devices. The evaluation of the results is carried out in accordance with the normative tabular data.

Indications and contraindications

Ultrasound examination of the organs of vision is a non-invasive diagnostic method used to detect many ophthalmic diseases.

Indications for ultrasound of the eyes are:

diagnosis of retinal detachment, choroid associated with the tumor process and other pathologies,
confirmation of the presence of neoplasms, control of their growth and effectiveness of treatment,
differential diagnosis intraocular tumors,
determining the position of the lens in corneal clouding,
scanning of the nature of the opacities of the vitreous body,
revealing the invisible foreign bodies in the eye (after injury), specification of their size and localization,
diagnosis of vascular ophthalmopathologies,
detection of cysts
diagnosis of congenital diseases,
detection pathological changes with a deep lesion of the eyeball in the orbit (determination of the nature of the damage - a fracture of the wall of the orbit, a violation of nerve connections, a decrease in the apple itself),
clarification of the cause of the displacement of the eyeball forward - autoimmune pathologies, tumors, inflammation, anomalies in the development of the skull, high unilateral myopia,
determination of changes in the retrobulbar space with increased intracranial pressure, retrobulbar neuritis and other diseases.

Contraindications for ultrasound diagnostics are eye injuries, in which the integrity of structures and bleeding in the organs of vision are violated.

Techniques

There are several methods ultrasound eye:

1. Ultrasound of the eyes in A-mode, in which one-dimensional display of the signal is obtained. There are 2 varieties of it:

biometric, the main purpose of which is to determine the length of the ACL (this data is used before cataract surgery and for accurate calculation of the artificial lens),
standardized diagnostic is a more sensitive method that allows you to identify and differentiate changes in the intraocular tissues.

2. Ultrasound in B-mode. The resulting echo display is two-dimensional, with horizontal and vertical axes. As a result, the shape, location and size of pathological changes are better visualized. The ultrasonic sensor is in direct contact with the surface of the eye (through a water bath or gel). It is the most acceptable way to study the structures of the eye, but it is not very informative for diagnosing corneal diseases. The advantage of scanning in this mode is the creation of a real two-dimensional picture of the eyeball.

3. Ultrasonic biomicroscopy, used to visualize the anterior segment of the eye. The frequency of ultrasonic vibrations is higher than that of the previous methods.

In more rare cases The following types of ultrasound examinations are used:

1. Immersion ultrasound in B-mode. It is done in addition to other research methods to study the pathologies of the anterior retinal edge, which are located too close on a standard B-scan. A small bath filled with saline is placed over the eye as an intermediate medium.
2. Color dopplerography. Allows you to simultaneously obtain a two-dimensional image and evaluate the blood flow in the blood vessels. Since the vessels are small, it is not possible to visualize their exact localization. The blood flow is coded in red (arteries) and blue (veins). The method also allows you to determine the growth of blood vessels in tumors, evaluate pathological deviations of the carotid and central arteries, retinal veins, damage to the optic nerve due to insufficient blood circulation.
3. Three-dimensional ultrasound examination. A 3D image is obtained by programmatically merging multiple 2D scans with the sensor in the same position but rotating rapidly. The resulting scan can be viewed on various slices. Three-dimensional ultrasound is indispensable in ophthalmic oncology (to determine the volume of melanomas and evaluate the effectiveness of therapy).

At the initial stage of cataract, the clouding of the lens of the ultrasound does not allow to detect. Upon reaching a certain maturity of the disease, the study shows various options for its echo transparency.

In ophthalmology, both specialized and universal ultrasound devices are used. In the latter case, the resolution of the sensors must be at least 5 MHz. The sensors of universal ultrasound devices are large, which makes it impossible to apply them directly to the orbit due to its rounded shape. Therefore, eye-mounted liquid gaskets can be used as an intermediate medium. The small working surface of specialized ophthalmic sensors makes it possible to visualize the intraorbital space.

Advantages and disadvantages

The advantages of the method of ultrasound examination of the eye include:

No thermal effects.
The ability to obtain information about the state of the anatomical regions located near the orbit.
High sensitivity in the study of intraocular hemorrhages and detachment processes, especially with clouding of the optical media of the eye, when traditional ophthalmic diagnostic tools are not applicable.
Precise determination of the area of retinal detachment.
The possibility of assessing the volume of hemorrhage, according to which further treatment tactics are determined (2/8 of the volume of the vitreous body - conservative treatment, 3/8 - surgical intervention).

The disadvantages of ultrasound of the organs of vision are the following:

contact of the sensor with the surface of the eyeball,
measurement error due to compression of the cornea,
inaccuracies associated with the human factor (not strictly perpendicular location of the sensor),
risk of infection in the eye.

Features of the examination in children

Ultrasound of the eye is performed at any age, but in young children it is difficult to achieve immobility and closure of the eyelids. This examination technique helps to identify congenital abnormalities in the organs of vision (retinopathy of prematurity, colobomas of the choroid and optic nerve head, and other pathologies). In children younger and school age The main indication for the appointment of ultrasound is myopia.

In newborns, the refractive power of the optical system of the eyes is weaker than in adults, and the size of the eyeball is smaller (16 mm versus 24 mm). Normally, after birth, there is a “reserve” of farsightedness of 2-5 diopters, which is gradually “used up” as children and the eyeball grow. By the age of 10, its value reaches the corresponding size in an adult, and the focus of the image falls exactly on the retina (“one hundred percent” vision).

After 7 years, the load on the visual apparatus of children increases greatly, which is most often associated with studying at school, burdened by heredity and weakness of accommodation - the ability of the lens to change its shape in order to see equally well near and far. Ultrasound diagnostics is the main method for determining the PZO (axial size of the eye) in children in the diagnosis of myopia with accommodation spasm. In connection with the peculiarities of growth, it is recommended to conduct an ultrasound scan for a child of 10 years old to detect elongation of the anteroposterior axis of the eye.

If refractive errors were detected at an earlier age, then the examination is carried out earlier. Lack of full vision correction up to 10 years leads to pronounced functional visual impairment and strabismus. Additionally, the transverse size of the eyeball and the acoustic density of the sclera are determined.

Measurement of PZO is the only reliable method for determining the progression of myopia. The main criterion is an increase in the anteroposterior axis of the eyeball by more than 0.3 mm per year. With the progression of myopia, all structures of the eye are stretched, including the retina, which can lead to serious complications - its detachment and loss of vision.

Carrying out the procedure

No special preparation is required before the procedure. When scanning the orbits of the eye in women, it is necessary to remove cosmetics from the eyelids and eyelashes. The patient is placed on his back so that the head is near the doctor. A roller is placed under the back of the head so that the head takes a horizontal position. In some cases, if it is necessary to determine the displacement of any structures of the eye or if there is a gas bubble in the orbit, the patient is examined in a sitting position.

Scanning is performed through the lower or upper closed eyelid, the gel is preliminarily applied. During the procedure, the doctor presses a little on the sensor, but it is painless. If a specialized transducer is used, the patient's eyes can be opened (subject to local anesthesia).

Diagnosis of the structures of the eyeball is done in the following order:

examination of the anterior part of the orbit (eyelids, lacrimal glands and sac) - plain scan,
to obtain a cut through the anteroposterior axis (APA), an ultrasonic sensor is installed on the closed upper eyelid above the cornea, at this moment the central zone of the fundus, the iris, the lens, the vitreous body (partially), the optic nerve, fatty tissue become available to the doctor,
to study all segments of the eye, the sensor is placed at an angle in several positions, while the patient is asked to look down towards the inner and outer corners of the eye,
an ultrasound head is applied to the inner and outer part of the lower eyelid (the patient's eyes are open) in order to visualize the upper part of the structures of the orbit,
if it is necessary to assess the mobility of the identified formations, then the person being examined is asked to make quick movements with the eyeballs.

Eye segment scanning

The duration of the procedure is 10-15 minutes.

Research results

During the examination, an ultrasound specialist fills out a protocol with a conclusion. The interpretation of the ultrasound results is done by the attending ophthalmologist, comparing them with tabular normative indicators:

Normal performance ultrasound examination of the eye in adults

Normal PZO values in children are shown in the table below. With various eye diseases, this figure varies.

Normal indicators in children

Normally, the image of the eyeball is characterized as a rounded formation of a dark color (hypoechoic). In the anterior section, two light stripes are visualized, representing the lens capsule. The optic nerve appears as a dark, hypoechoic band at the back of the eye chamber.

Normal blood flow measurements on color Doppler ultrasound

Below is an example of an eye ultrasound protocol.