Methods of ultrasound examination of the eye

To conduct ultrasound in patients with an ophthalmic profile, sensors with an operating frequency of 7.5-13 MHz, an electronic linear and a microconvex sensor are used, and in the equipment of an earlier release also a mechanical sector scan (with a water nozzle) to obtain a sufficiently clear image of surface structures. The patient is placed in such a way that the doctor is at the head of the patient (as with ultrasound of the thyroid and salivary glands). The examination is performed through the lower or closed upper eyelid (transcutaneous, transpalapebral scanning method).

When examining the eye, its adnexa and orbit, observe a certain sequence of setting the sensor and the direction of the patient's view for performing a comprehensive, segmental examination of the intraocular structures, taking into account the anterior and posterior segments, and dividing by 4 quadrants of the eyeball and the presence of the central zone of the ocular fundus . In the orbit, the upper, lower, inner and outer divisions are distinguished, and the region of the apex of the orbit is distinguished.

To detect changes in the area of the adnexa of the eye (eyelids, tear gland, tear sack), conduct an overview scan in the transverse, longitudinal and oblique planes.

By placing the sensor on the closed upper eyelid above the cornea (transverse scan), an eyeball slit is obtained through its anteroposterior axis, which allows to assess the condition of the central zone of the fundus and the ultrasound of the anterior chamber, iris, lens and part of the vitreous humor, as well as the central part retrobulbar space (optic nerve and fatty tissue).

In the future, for a segmental examination of the eye, a sensor is installed in series obliquely:

• outside on the closed upper eyelid, while the patient is asked to look down to the inside, the direction of scanning - there; Thus, for inspection, the inner-lower segment of the eyeball and a similar section of the retrobulbar space become available;
• on the inner part of the closed upper eyelid (the direction of the patient's view and the ultrasound ray downwards outside) - examine the lower-segment segment of the eye and orbit;
• on the inner part of the lower eyelid with open eyes (direction of view and scanning upward from the outside) - assess the upper segment of the eyeball and orbits;
• on the outer part of the lower eyelid with open eyes (direction of sight and scanning upward to the inside) - visualization of the upper-inner segment of the eye and orbit is achieved.

To obtain an image of the rectus muscles in the retrobulbar space, the sensor is set as follows:

• for visualization of the lower rectus muscle - on the closed upper eyelid (direction of vision and ultrasound of the ray down, transverse scan);
• the upper rectus muscle - on the lower eyelid with the eyes open (direction of sight and ultrasound upward, transverse scan);
• external rectus muscle - with closed eyes at the inner corner of the eye gap (direction of view and ultrasound from outside; longitudinal scanning);
• the internal rectus muscle - with the eyes closed at the outer corner of the eye gap (the direction of sight and ultrasound of the beam inside, longitudinal scanning).

In this case, intraocular structures on the border of the lower segments, upper segments, outer segments, internal segments of the eye are successively correspondingly seen. As with the examination of other organs, during the study, it is necessary to constantly change the angle of the sensor.

For the organ of vision, hemodynamically significant changes in the blood flow along the eye artery, upper eye vein, central artery and retinal vein, posterior short ciliary arteries, as well as in newly formed vessels of tumors and tumor-like foci play the most important role.

To identify the most important vessels of the organ of vision use certain guidelines.

The eye artery (HA) is the main and largest arterial vessel in orbit that extends from the internal carotid siphon, giving rise to a vast branched network that supplies the soft tissues of the retrobulbar space, including muscles, the eyeball, and the lacrimal gland. Its proximal part is visualized deep in the central part of the orbit, intersects with the optic nerve and then spreads into the upper medial orbit. Immediate continuation of the eye artery is the supraclavicular artery that emerges from the periorbital region to the surface of the frontal part of the skull medial to the supraorbital artery. When dividing the eye artery into many branches immediately at the entrance to the orbit ("loose" and not "trunk" type of vessel), it may be difficult to identify it, but such variants are relatively rare. The easiest way to identify the eye artery in the orbit is to set the sensor in the manner described above for visualization of the inferior part.

The upper eye vein (HBV) is the largest vessel of the venous channel of the orbit, it is fairly easy to identify in the upper medial department with the appropriate location of the sensor according to the proposed procedure. The upper eye vein is directed from front to back, from top to bottom, partly with an S-shaped bend. Together with the lower ophthalmic vein, which in some cases can be absent, drains into the cavernous sinus venous blood.

The central artery of the retina (CAC) is the branch of the eye artery most easily identified in the optic nerve for about 1 cm from the place of its exit from the eyeball. It is located in conjunction with the vein. When mapping is different from the last by staining in red and arterial blood flow. It gives rise to the retinal vessels, branched out on the surface of the optic disc.

The central vein of the retina (CVS) is an important anatomical formation for the eye, is formed from the fusion of the retinal veins, is visible in the optic nerve at the posterior pole of the eyeball near the central artery of the retina, stained blue with the recording of venous blood flow.

The posterior short ciliary arteries (CCCA) are several branches of the eye artery (up to 12) located around the optic nerve, in the immediate vicinity of it, perforating the sclera, participating in the blood supply of its disc.

Outside the posterior short ciliary arteries, it is possible to distinguish posterior long ciliary arteries on both sides, which differ somewhat in their rates of blood flow; in the region of the eyeball equator with some technical difficulties - four vorticious veins (two on each side). In the lateral part of the orbit, one of the large branches of the eye artery is easily visualized: a lacrimal artery, which leads to the lacrimal gland and divides there into smaller branches.

Taking into account the spectral characteristics of the blood flow, the arteries of the eye and orbit are referred to vessels of conditionally peripheral type. The blood flow in them is mono- or biphasic, mediocre resistant, with acute systolic spikes, but with a diastolic component in the norm never falls below the isoline. People over the age of 50 years notice a certain flatness of the peaks due to a decrease in the elasticity of the vascular wall.

The venous blood flow spectrum (in HBV and CVS) is sometimes approximated to the linear form, and more often - biphasic, due to fluctuations associated with the cardiac cycle. DMSH in the CVV is usually recorded together with the arterial blood flow to the CAC, but is located below the isoline. The maximum speed is quite variable: on average from 4 to 8 cm / s in the CVS and from 4 to 14 cm / s in HBV.

[1], [2], [3], [4], [5], [6], [7]