Penetrating Intraocular Injuries
Penetrating intraocular injuries with retained foreign bodies are seen most frequently in dogs and cats. They are often associated with lead pellets and bullets that partially or totally traverse the ocular tunics, but splinters or spines (eg, cactus) can also cause a penetrating injury. Pellets or bullets usually cause self-sealing, slightly tan corneal defects; may cause intraocular hemorrhage; and may traverse the lens and posterior segment wall. Perforation of the lens can lead to rapid cataract formation, especially when the anterior lens capsular tear is longer than 2 mm. Vitreal and retinal hemorrhage and retinal detachments are likely. Ophthalmic ultrasonography and orbital radiology are most helpful to assess pellet location and the integrity of the intraocular and orbital tissues. Anterior lens laceration and rupture is also a common sequela of cat claw injuries in young dogs.
Penetration of the anterior lens capsule (lacerations >2 mm) requires lens removal as soon as possible, because escape of lens material causes gradually intensifying lens-induced uveitis that often progresses to secondary glaucoma and phthisis bulbus. The posterior segment changes usually resolve provided the retina eventually reattaches. Focal retinal degeneration in the area of retinal penetration and detachment is common. Prognosis is guarded and based, in part, on the response to therapy and gradual clearing of the intraocular media.
Therapy is directed at controlling the post-traumatic inflammation and maintaining normal levels of intraocular pressure. Mydriatics and topical and systemic antibiotics and corticosteroids are administered to control the uveitis. Intraocular hemorrhage is allowed to resolve, with anterior chamber hemorrhage usually disappearing in ~1–2 wk and the vitreal hemorrhage resolving in 3–6 mo.