Contributor: Gordon K. Klintworth
A wide variety of foreign materials enter the eye during a penetrating injury. Foreign bodies may also enter the eye by accompanying sharp objects that perforate the globe. Some are propelled at a considerably velocity and may transverse the eye completely. More often the foreign body remains in the wall of the globe or ends up in the vitreous or in another part of the eye. Small particles often lodge in the superficial ocular tissues. Some foreign bodies penetrate into or through the globe. When they travel at high velocity (as from industrial machinery) the patient may be unaware of the injury even if the foreign body has entered the eye. A foreign particle entering the eye may damage the tissue directly. Others lead to an infection by permitting an entry of microorganisms. Some foreign bodies provoke a prominent acute inflammatory or granulomatous reaction. Other complications of ocular injuries include cataracts [cataract], retinal detachment and glaucoma.
Sterile foreign objects may not evoke inflammation or have other adverse effects. Whereas other foreign bodies cause a significant tissue response. Copper [foreign body - copper] and iron [foreign body - iron] containing foreign bodies are particularly toxic. Lead, zinc, nickel, aluminum, and mercury may also evoke intraocular inflammation. Vegetable matter, hair, and skin may enter the ocular tissues following an explosive or perforating injury. These agents will incite an inflammatory reaction, which occasionally may be granulomatous in nature. EDEX is often helpful in identifying the composition of intraocular foreign bodies. Intraoperative vitreous loss and incarceration predispose to infection, retinal detachment, and defective wound healing. Incarcerated vitreous can serve as a scaffold for a fibrous ingrowth. Rarely, corneal epithelium or conjunctival epithelium enters the eye through inadequately apposed surgical wounds or intraoperative seeding as an epithelial downgrowth.