8th December 2023

Foreign bodies

In this section, discussion of foreign bodies will be limited to those on the ocular surface (conjunctiva and cornea). Materials can become embedded on the ocular surface, particularly if sharp or moving at a high velocity. Corneal or conjunctival foreign bodies tend to occur as occupational hazards. Foreign bodies can slip between the gaps in the frame, even in those who use safety glasses. It is important to ascertain the velocity and size of the foreign body as this informs the risk of a penetrating eye injury or intraocular or intraorbital foreign body.

Foreign bodies can be organic or inorganic, and organic matter carries a higher risk of infection due to the presence of microbes. Patients present with a history of redness, watering and foreign body sensation. Examination should include eversion of the lid to look for subtarsal foreign bodies and the fornices should be swept and examined.

Image Source: Wikimedia Commons (2007). Foreign body in eye, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Foreign_body_in_eye.jpg (Accessed on: 5  May 2022).

Image Source: Wikimedia Commons (2018). Foreign body on cornea, Licensed under a creative commons licence. Available for free at: https://commons.wikimedia.org/wiki/File:Foreign_body_on_cornea.png (Accessed on: 5  May 2022).

Iron and copper are toxic to cells and induce inflammation. Foreign bodies not deeply embedded need removal. Iron and copper foreign bodies leave a rust ring on removal, and this should also be removed as it induces inflammation and is toxic. On detection of a foreign body, attempt to remove it with a swab or irrigate it. Prophylactic topical antibiotic such as chloramphenicol should be given after removal to prevent bacterial infection. If there is suspicion of a penetrating eye injury, a shield should be placed over the eye, and urgent ophthalmology assessment sought, as should also be the case when there are unsuccessful attempts or inadequate removal of foreign body. Protective eyewear significantly decreases the risk of foreign bodies.