X-ray of the eye socket
Last reviewed: 19.11.2021
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The organ of vision consists of the eyeball, its protective parts (eye socket and eyelids) and appendages of the eye (tear and movement apparatus). Glaznitsa (orbit) in shape resembles a truncated tetrahedral pyramid. At its top there is an opening for the optic nerve and orbital artery. At the edges of the visual aperture 4 straight muscles are attached, the upper oblique muscle and the muscle lifting the upper eyelid. The walls of the eye sockets are composed of many facial bones and some bones of the cerebral skull. From the inside the walls are lined with the periosteum.
The image of the eye sockets is on the survey radiographs of the skull in a straight, lateral and axial projections. In the picture in a direct projection with the nose-chin position of the head relative to the film, both eye sockets are seen separately, and the entrance to each of them in the form of a quadrilateral with rounded corners is very clearly distinguished. Against the background of the orbit, a narrow narrow upper glaucoma is defined, and under the entrance to the orbit there is a circular opening through which the infraorbital nerve emerges. On the lateral shots of the skull, the images of the eye sockets are projected onto each other, but it is not difficult to distinguish between the upper and lower walls of the orbit adjacent to the film. On the axial radiograph, eye sockets are partially overlapping the maxillary sinuses. The opening of the optic nerve canal (round or oval shape, diameter up to 0.5-0.6 cm) is imperceptible in the survey images; for his research, a special photograph is taken, separately for each side.
The image of eye sockets and eyeballs free from imposition of neighboring structures is achieved on linear tomograms and especially on computer and magnetic resonance tomograms. It can be argued that the organ of vision is an ideal object for AT in view of the pronounced differences in the absorption of radiation in the tissues of the eye, muscles, nerves and vessels (about 30 HU) and retrobulbar fatty tissue (-100 HU). Computer tomograms allow you to obtain an image of the eyeballs, the vitreous and the lens in them, the membranes of the eye (in the form of the total structure), the optic nerve, the orbital artery and vein, the muscles of the eye. For best visualization of the optic nerve, a cut is made along a line connecting the lower edge of the orbit with the upper edge of the external auditory canal. As for magnetic resonance imaging, it has special advantages: it is not accompanied by x-ray irradiation of the eye, makes it possible to examine the orbit in different projections and differentiate blood clusters from other soft tissue structures.
New horizons in the study of the morphology of the organ of vision opened an ultrasound scan. The ultrasonic devices used in ophthalmology are equipped with special eye sensors operating at a frequency of 5-15 MHz. They minimize the "dead zone" to the minimum - the nearest space in front of the piezo-plate of the sound probe, within which echoes are not recorded. These sensors have a high resolution - up to 0.2 OD mm in width and in the front (in the direction of the ultrasonic wave). They make it possible to perform measurements of various eye structures with an accuracy of 0.1 mm and to judge the anatomical features of the structure of the biological media of the eye on the basis of the amount of ultrasound attenuation in them.
Ultrasound examination of the eye and orbit can be performed by two methods: the A-method (one-dimensional echography) and the B-method (sonography). In the first case, echoes are recorded on the oscilloscope screen corresponding to the reflection of ultrasound from the boundaries of the anatomical environment of the eye. Each of these boundaries is reflected on the echogram in the form of a peak. Between isolates, the isolines are normally located. Retrobulbar tissues cause on a one-dimensional echogram signals of different amplitude and density. On sonograms, an image of the acoustic cut of the eye is formed.
In order to determine the mobility of pathological foci or foreign bodies in the eye, sonography is performed twice: before and after a rapid change in the direction of vision, or after a change in the position of the body from vertical to horizontal, or after exposure to a foreign body by a magnetic field. Such a kinetic echography makes it possible to determine whether a focus or foreign body is fixed in the anatomical structures of the eye.
On the survey and sighting radiographs it is easy to determine the fractures of the walls and edges of the orbit. Fracture of the lower wall is accompanied by a darkening of the maxillary sinus due to hemorrhage into it. If a crack in the orbit penetrates into the paranasal sinus, air bubbles in the orbit (emphysema of the orbit) can be detected. In all the unclear cases, for example, with narrow cracks in the walls of the orbit, CT helps.