Penetrating Intraocular Injuries in Small Animals

Penetrating intraocular injuries are observed most frequently in dogs and cats. They are often associated with cat claw injuries or plant foreign bodies (eg, cactus); however, lead pellets and bullets that partially or totally traverse the ocular tunics can also result in a penetrating injury.

Anterior lens laceration and rupture is a common sequela of cat claw injuries in young dogs. Thus, it is critical to assess for lens perforation, which can lead to cataract formation or severe, uncontrollable uveitis, particularly if bacteria are implanted within the lens (see penetrating corneal foreign body image). A dilated examination of the lens with retroillumination as well as with a slit beam is important. Because of the reflex anterior uveitis, multiple drops of tropicamide and/or atropine may need to be administered. If extensive hemorrhage or fibrin is present or the iris is resistant to dilation, the dilated exam may need to occur at a follow-up appointment after the condition has resolved.

Penetrating corneal foreign body, dog

Image

Courtesy of UC Davis Comparative Ophthalmology Service.

Patients should also be assessed for vitreous and retinal hemorrhage, and retinal detachments are likely if the injury is from a lead pellet or bullet.

Corneal cytological evaluation and aerobic bacterial and fungal cultures should be considered, particularly if the injury is chronic or demonstrates clinical signs of infection, including stromal cellular infiltrate, stromal loss, or keratomalacia.

A fluorescein stain should be performed to assess the size of the lesion and to determine whether active aqueous humor leakage is present (Seidel test).

Ophthalmic ultrasonography and orbital radiology are helpful to assess pellet location and the integrity of the intraocular and orbital tissues.

Historically, it was thought that penetration of the anterior lens capsule (lacerations > 2 mm) required 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 bulbi. However, dogs and even cats with large corneal lacerations and concurrent lens capsule ruptures can be successfully managed with medical treatment that includes topical and systemic broad-spectrum antimicrobials, a topical mydriatic (eg, atropine), and a systemic corticosteroid or NSAID. Nevertheless, referral to an ophthalmologist should always be offered in these cases so that surgical management can be provided if needed.

The visual prognosis is guarded if the posterior segment is involved, particularly if the retinal detachment is large. If the penetrating injury involves only the cornea, then the prognosis for vision and globe retention is good. However, concurrent lens capsule rupture with posterior segment involvement carries a more guarded prognosis. In cats with lens capsule involvement, a discussion of the risk of traumatic lens-induced sarcoma is warranted, as well as the requirement for regular dilated ocular examinations.

Regardless of whether medical or surgical treatment is instituted, it is critical that the patient is kept quiet and an Elizabethan collar (E-collar) is placed to prevent self-trauma. Frequent rechecks will also be required to ensure proper healing is occurring and to assess for concurrent infection.