Diagnosis of foreign bodies in the eye

To detect fragments, the following conditions are necessary: transparency of the medium lying in front; location of fragments in the area accessible for clinical examination. If, when a foreign body is introduced into the eye, there is no significant damage to the eyeball and no gaping wounds are formed, then the Komberg-Baltik X-ray method is used to determine the localization of an intraocular foreign body. An indicator prosthesis is used. It is an aluminum ring with an 11 mm diameter hole for the cornea in the center. The set has three prostheses. They are selected for patients taking into account the radius of curvature of the sclera. Four lead marks are soldered along the edge of the prosthesis opening. After local anesthesia, the indicator prosthesis is applied to the eye so that its marks are located along the limbus according to the 3-, 6-, 9-, and 12-hour meridians. Two X-ray images are taken - in direct and lateral projections. Then, measuring schemes are placed on the images and it is determined in which meridian the foreign body is located, at what distance from the sagittal axis and from the limbus plane. This is the most common method of detecting foreign bodies, but it does not always help to establish the presence of a foreign body or to determine exactly whether it is located in the eye or outside the eye.

To determine the location of foreign bodies in the anterior segment of the eyeball, the Vogt skeleton-free radiography method is used no earlier than 7-100 hours after the injury. In clinical practice, other methods are also used to detect foreign bodies in the eye. Information about the location of the fragment and its relationship with the eye membranes is obtained using an ultrasound diagnostic method using B-scanning. In difficult diagnostic cases, a computed tomography study is performed. In cases where conventional radiography fails to detect a foreign body inside the eye, and clinical data indicate its presence, it is advisable to use radiography with direct magnification of the image. This method allows you to detect the smallest foreign bodies (at least 0.3 mm), located not only in the anterior, but also in the posterior segment of the eyeball. In addition, radiography with direct magnification can detect low-contrast foreign bodies that are poorly or not at all visible on conventional radiographs.

When examining patients with extensive damage to the eyeball and prolapse of the intraocular membranes, as well as young children, when the use of contact methods for determining the localization of intraocular foreign bodies is contraindicated or difficult to implement, a non-contact method should be used.

When examining patients with multiple foreign bodies, the stereo-radiographic method of their localization is invaluable. This method is also advisable to use in the presence of non-fixed fragments located in the vitreous body, since in such cases the patient's position during the X-ray examination and on the operating table is the same. With these methods, it is possible to detect a fragment in the eye in 92% of all patients. Only the smallest glass fragments localized in the anterior segment of the eye or practically destroyed as a result of a long stay, as well as foreign bodies located in the posterior part of the eye (8% of cases) remain undetected. Computer axial tomography is used to detect intraocular foreign bodies. The advantages of the method are the speed and painlessness of the examination, as well as obtaining accurate information on the relationship of the foreign body and intraocular structures. It is especially advisable to use the method in the case of multiple foreign bodies. The minimum size of a metal fragment detected by tomography is 0.2×0.3 mm; glass - 0.5 mm.

At present, electronic locator devices are widely used for diagnostics, with the help of which the localization of metallic foreign bodies and their magnetic properties are determined. The method of examining patients with the help of any locator is as follows. First, a foreign body is determined in the eye by bringing the sensor to different parts of the eyeball; at the same time, the deviations of the arrow from the middle of the scale and the sign of this deviation are recorded. In case of detection of a foreign body in the eye, the localization is determined in the described way by the maximum deviation of the indicator arrow from the beginning of the count; the place in the eye to which the sensor was brought at the moment of maximum deviation corresponds to the closest location of the intraocular foreign body in relation to the membranes of the eyeball. In the event that the deviation of the indicator arrow is small, the sensitivity of the device is increased.

The device can be used in outpatient settings to quickly identify a metal fragment in the eye and its approximate location. The device can also be used during the removal of a foreign body from the eye to clarify the location.

One of the valuable methods for diagnosing foreign bodies in the eye is ultrasound. Ultrasound is used in the treatment of foreign body wounds to determine the location of the foreign body and, more importantly, to obtain an accurate characterization of traumatic eye injuries.

Currently, both one-dimensional echography and scanning echography are used for ultrasound diagnostics of foreign bodies in the eye. The type of echogram can be used to determine the nature of pathological changes, as well as differentiate each of them, in particular, to establish the presence of a foreign body. Ultrasound examination is performed using the domestic ultrasound diagnostic device "Echo-ophthalmograph". This method is effective only in combination with radiography and in no case can be used as an independent diagnostic method.

Once the presence of a foreign body in the eye has been established, it is important to clarify its nature: whether the fragment is magnetic or amagnetic. There are a number of tests for this: echographic localization of fragments is performed using the Ecoophthalmograph ultrasound device; the locators described above are used to determine the magnetic properties of the fragment. These also include the metallophone created by P. N. Pivovarov. When the metallophone probe approaches a metallic foreign body, the tone in the phone headphones changes - a "sound splash". Magnetic fragments produce a higher tone than the main one. Foreign bodies with a diameter of less than 2 mm are difficult to distinguish by sound, so the device can be used mainly to detect a fragment in the eye and determine its localization.

To detect very small fragments of iron or steel, the sideroscopy method is used. In the most difficult cases, a chemical examination of the anterior chamber helps to determine the presence of a foreign body and clarify its nature. Such an examination is carried out in extreme cases when all other methods are ineffective. A chemical examination of the fluid of the anterior chamber for iron allows early signs of siderosis or chalcosis to be detected. However, the test may be negative if the foreign body is surrounded by a connective capsule.

In recent years, fundamentally new methods for diagnosing foreign bodies have been developed. They describe the method of television ophthalmoscopy in light, as well as color cinematography of the fundus, used to determine the localization of fragments in the retina. Using special filters, it is possible to determine the presence of an intraocular body with clouding of the cornea and lens. The phenomena of retinal siderosis can be detected using fluorescent angiography of the retina and optic nerve.

Foreign body diagnostics are also performed using an electromagnetic sensor. The method allows determining the depth of the foreign body, its size and the type of metal.

All the above methods of diagnosing foreign bodies allow us to determine whether there is a fragment in the eye, as well as its magnetic properties. In the future, when removing the fragment, it is extremely important to determine its projection on the sclera.

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Methods for refining the projection of a foreign body onto the sclera

The tactics of surgical intervention largely depend on the site of implantation and the size of the fragment, as well as the time that has passed since the eye injury. In order for the diascleral operation to be successful, it is necessary to determine the exact location of the foreign body and make an incision in the area of the sclera as close as possible to the fragment, practically above it.

There are several ways to transfer the projection and the rock body to the sclera, special calculations and tables have been proposed to determine the projection site of ophthalmoscoped fragments and pathological foci on the sclera. Currently, generally accepted radiological methods for determining the localization of intraocular fragments allow us to determine the following parameters:

1. meridian of fragment occurrence;
2. its distance from the anatomical axis of the eye;
3. the depth of the fragment in a straight line from the plane of the limb.

The first two parameters without corrections are used for diascleral removal of the fragment.

A transillumination method using a diaphanoscope, which is placed on the cornea. In this case, a light scleral transillumination is clearly visible, against which a dark spot of a foreign body stands out. This method is very valuable in removing both magnetic and amagnetic foreign bodies located parietal and in the membranes of the anterior and posterior sections of the eye.

Thus, the following scheme for determining the localization of a foreign body on the sclera is proposed.

Clinical determination of the location of a foreign body

1. X-ray diagnostics of the fragment and determination of the size of the eyeball (using X-ray and ultrasound methods).
2. Clarification of the projection of a foreign body onto the sclera using a table taking into account the size of the eyeball.
3. Using the parametria method in transparent media to clarify the localization of a foreign body.
4. A mark on the sclera at the supposed location of the foreign body, depending on the condition of the eye, is made as follows:
   • in transparent environments, after preliminary ophthalmoscopy, a coagulate is applied using a diathermocoagulation apparatus, then a repeated ophthalmoscopic examination is performed (the relative position of the coagulate and the foreign body is determined), the localization is clarified using the transillumination method;
   • In case of cataracts or opacification of the vitreous body, transillumination is used with a diaphanoscope, which allows the foreign body to be projected onto the sclera with a certain degree of accuracy;
   • when the fragment is located far beyond the equator, in the posterior part of the eyeball, retrobulbar diaphanoscopy is used;
   • In case of hemophthalmos, as well as in case of location of a foreign body in the ciliary body, transillumination with a diaphanoscope with a light guide, electronic location, ultrasound diagnostics or suturing of marks can be used. However, the latter method can be recommended in the most extreme cases. This method can be used in case of hemophthalmos, when transillumination and retrobulbar diaphanosconia do not give an effect.

The use of all the above methods to clarify the projection onto the sclera of magnetic and amagnetic foreign bodies located near the wall or in the membranes of the eyeball ensures the effectiveness of the fragment removal operation.

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