Foreign bodies in the eye

A foreign body entering the eye causes:

1. destruction, the degree of which depends on the mass of the fragment, its shape, and its flight trajectory;
2. eye infection;
3. prolapse of membranes;
4. hemorrhages.

The fragment causes inflammation, leading to mooring and metallosis.

All fragments must be removed, but their removal must be less traumatic than leaving them, and those that can be removed.

Classification of fragments

The smallest - up to 0.5 mm; small - up to 1.5 mm; medium - up to 3 mm; large - up to 6 mm; giant - more than 6 mm; long - rarely of the same size and especially long. Interaction of fragments with shells:

1. fragments freely moving in the vitreous body;
2. fragments that are relatively mobile in the vitreous body;
3. shell fragments - motionless;
4. in the lens - motionless.

By interaction with shells: partially embedded, with a braking zone, rhinolet (possibly freely moving and secondary interaction with shells). 99% of fragments are not detected.

Small foreign bodies such as steel, coal or sand particles often become lodged on the surface of the cornea or conjunctiva. These foreign bodies may subsequently:

• To be washed away by tears into the tear duct system.
• Stick to the palpebral conjunctiva of the upper eyelid in the subtarsal groove and traumatize the cornea with each blink. A subtarsal foreign body may not be noticed unless the upper eyelid is everted during examination.
• Migrate and remain in the superior conjunctival fornix, and then provoke chronic conjunctivitis. Such foreign bodies are also easy to miss if the eyelids are not everted and the fornix is not examined.
• Invade the bulbar conjunctiva.
• Penetrate the corneal epithelium or stroma to a depth proportional to the speed of the foreign body.
• High-velocity foreign bodies can penetrate the cornea, sclera and intraocularly.

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Corneal foreign bodies

Clinical features. Corneal foreign bodies are extremely common and cause significant irritation. After some time, leukocyte infiltration forms around any foreign body. If the foreign body is not removed, there is a high risk of secondary infection and corneal ulceration. Moderate so-called secondary uveitis is characterized by miosis, irritation and photophobia. Around an iron foreign body, rust deposits begin to form in the bed of its occurrence after a few days.

Treatment

• A thorough slit lamp examination is necessary to determine the exact location of the foreign body and its depth;
• The foreign body is removed under slit lamp control using an insulin needle. A magnet is convenient for deeply embedded metallic foreign bodies. The residual "rusty ring" (scale) can be easily removed with a sterile "burr";
• Antibiotics in ointment form are used together with cycloplegic drugs and/or ketorolac to ensure comfort.

If there is discharge, infiltration, or marked uveitis, a secondary bacterial infection should be suspected; follow-up should be as for a corneal ulcer. Metallic foreign bodies are usually sterile due to the significant increase in temperature when passing through the air; organic and stone foreign bodies are more likely to carry infection.

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Intraocular foreign bodies

Intraocular foreign bodies may cause mechanical trauma to the eye, introduce infection, or exert toxic effects on intraocular structures. Once in the eye, a foreign body may localize in any of its structures into which it is embedded; thus, it may be located anywhere from the anterior chamber to the retina and choroid. Visible mechanical effects include the development of secondary cataracts when the lens capsule is damaged, liquefaction of the vitreous body, retinal ruptures, and hemorrhage. Stones and organic foreign bodies are especially dangerous due to infection. Many substances, including glass, various plastics, gold, and silver, are inert. However, iron and copper may dissociate and lead to the development of siderosis and chalcosis, respectively.

Siderosis of the eye

Iron fragments are among the most common foreign bodies. Intraocular iron foreign bodies undergo dissociation, ending with the deposition of iron fragments in the intraocular epithelial structures, especially on the lens and retina epithelium, exerting a toxic effect on the enzymatic system of cells and leading to their death. Signs of siderosis: anterior capsular cataract consisting of radial iron deposits on the anterior capsule of the lens, reddish-brown coloration of the iris, secondary glaucoma due to damage to the trabeculae, and pigmentary retinopathy. The latter mainly determines the prognosis for vision. Electroretinography after some time after the injury shows a progressive weakening of the b-wave.

Chalcose eyes

The reaction of the eye to an intraocular foreign body with a high copper content is similar to endophthalmitis, often with a progressive course up to the death of the eye. On the other hand, an alloy such as brass or bronze with a relatively low copper content leads to chalcosis. Electrolytically dissociated chalk is deposited inside the eye, forming a picture similar to that in Wilson's disease. Thus, the Kayser-Fleischer ring, an anterior capsular cataract in the form of a "sunflower flower", develops. Retinal damage is expressed as golden lamellar deposits, visible ophthalmoscopically. Since copper is less toxic to the retina than iron, degenerative retinopathy does not develop, and visual functions can be preserved.

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Diagnostics of foreign bodies in the eye

1. A history is needed to determine the origin of the foreign body; it would be reasonable for the patient to bring the objects from which the fragment bounced off, such as a chisel.
2. An ophthalmologic examination is performed, paying particular attention to any possible entry or exit sites of the foreign body. Fluorescein staining may help in identifying the entry site. Evaluation of the wound location and its projection onto the eye logically suggests the location of the foreign body. Gonioscopy and ophthalmoscopy should be performed. Associated signs such as lid lacerations and damage to anterior segment structures should be carefully noted.
3. CT in axial and frontal projections is necessary for diagnostics and localization of metallic intraocular foreign bodies. Cross-sections are performed, which are superior in diagnostic value to simple X-rays and echography.

NMR is contraindicated in the presence of metallic intraocular foreign bodies.

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Method of removing foreign bodies from the eye

Removal of foreign bodies with a magnet includes:

• sclerotomy at the site of attachment of the foreign body;
• low-intensity diathermy of the choroid to prevent bleeding;
• removal of foreign bodies with a magnet;
• cryopexy to fix retinal tears and adjacent retina;
• scleral depression to reduce the risk of retinal detachment, but this is not necessary.

Tweezers are used to remove non-magnetic foreign bodies and magnetic ones that cannot be safely removed with a magnet.

• perform total vitrectomy through the pars plana of the ciliary body;
• a small foreign body can be removed through the pars plana of the ciliary body;
• A large foreign body in the pupillary region of an aphakic eye can be removed with a keratome through a limbal incision.

Prevention of endophthalmitis by intravitreal administration of antibiotics is indicated in cases of high risk of infection, such as the introduction of foreign bodies of plant origin or contaminated soil.

Enucleation of the eye

Primary enucleation of the eye should be performed only in cases of very severe damage, when there is no prospect of restoring vision and the sclera cannot be restored. Secondary enucleation of the eye is performed after the primary treatment if the damage to the eye is severe and its functions cannot be restored, and also for cosmetic reasons or in case of discomfort. According to some researchers, it is recommended to perform enucleation within 10 days after the primary injury to prevent even a minimal possibility of sympathetic ophthalmia. However, there is no objective evidence for this fact. A temporary delay also allows patients to psychologically and emotionally adapt to the loss of the eye.

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