resuscitation in small animals - Maravet

IV. Ophthalmic Emergencies
Section Editor: Cynthia C. Powell, D.v.M., M.s.
36. ACUTE OCULAR TRAUMA
Cynthia C. Powell, D.V.M., M.S.
1. What are the major considerations in evaluating acute ocular injury?
Overall patient condition is the first consideration with acute trauma. Once the patient is
stable, attention then should be focused on the eye. Prognosis and therapeutic options vary depending
on cause and duration of injury and ocular structures involved. Ifother injuries preclude
immediate evaluation and attention to the injured eye, it should be protected from further damage
with lubricants and a protective collar if necessary. In cases of chemical injury, the globe should
be examined to determine its integrity, and lavage should be instituted immediately.
2. Are certain injuries more threatening to vision or the integrity ofthe globe?
Ocular proptosis and injuries that rupture or perforate the globe often result in vision loss or
require enucleation and carry a guarded prognosis. In general, blunt traumatic injury carries a
worse prognosis than sharp penetrating injury because of the increased incidence of retinal detachment
and broader scope of uveal damage. Alkali chemical burns, such as those due to ammonia,
lye, lime, and magnesium hydroxide, are more likely to cause globe or sight-threatening
injury than acid chemical burns.
3. Why are alkali injuries worse than acid injuries?
Most acids coagulate corneal epithelial and stromal proteins, thus forming a barrier and limiting
corneal penetration. Alkalis, however, saponify plasma membrane lipids, denature collagen,
and readily penetrate the cornea, increasing possibility of anterior segment damage.
4. How do you treat chemical burns of the eye?
Copious irrigation to decrease contact time and concentration should be instituted immediately
if a chemical burn is suspected or confirmed. Continuous lavage with a sterile solution of
lactated Ringer's and 5% dextrose in water or saline can be delivered through a standard IV set.
During irrigation the conjunctival and corneal surfaces should be inspected and cleaned of chemical
residue. Lavage should be continued for 30 minutes or until the pH of the ocular surface returns
to normal range (7.3-7.7). After irrigation the eye should be treated for corneal ulceration,
uveitis, and glaucoma when present.
5. Do any specific therapies for alkali burns help treatment and improve prognosis?
Alkali corneal burns decrease aqueous and corneal ascorbic acid levels and may result in impaired
collagen synthesis in the injured cornea. Evidence suggests that topical 10% sodium
ascorbate applied every 1-2 hours and high dosages oforal ascorbate, 30 mg/kg 4 times/day, may
decrease the incidence (but not progression) of sterile stromal ulceration after alkali chemical
injury. Treatment is continued at this level for I week when the topical medication is decreased to
4 times/day. Both topical and systemic medications are continued until the cornea is reepithelialized.
Topical sodium citrate 10% inhibits neutrophil activity and decreases sterile ulceration and
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