Exophthalmos - Dog

Introduction

Exophthalmos occurs when the equator of the globe advances beyond the margin of the palpebral fissure. It is also known as ocular proptosis.

Causes

Blunt trauma (eg road traffic accidents, dog fights) are the most common cause of exophthalmos.

Traumatic Exopthalmos

Treatment

Initial Management

• The globe should be kept moist - owners should be advised to keep the eye lubricated whilst transporting to the veterinary clinic
• The patient must be assessed for other injuries from the trauma that caused the exophthalmos. This is especially important in dolichocephalic breeds where considerable force is required to protrude the globe.

Decision Making

• 40-50% of dogs regain vision with surgical treatment.
• Negative prognostic indicators include:
  • Rupture of three or more extraocular muscles.
  • Lack of consensual pupillary light reflex to the contralateral eye.
  • Corneal laceration extending past the limbus.
  • Extensive hyphaema.

Surgical Treatment

The globe should be replaced under an general anaesthetic, followed by a temporary tarsorrhaphy to allow the tissues to heal:

• Clean the eye and periocular tissues with dilute povidone-iodine solution and sterile saline.
• Replace the globe. Lateral canthotomy is often required to allow this.
• Use three or four horizontal mattress sutures for the temporary tarsorrhaphy.
  • Use 1 or 1.5 metric suture material, some authors advocate using silk.
  • Use stents in the sutures to prevent eyelid necrosis.
  • Care must be taken with the placement of the sutures to avoid corneal ulceration or entropian.
  • Leave a small area open at the medial canthus to allow topical medication adminstration
• Close the canthotomy incision in two layers.
• Sutures should be removed after 10-14 days

If the globe is not salvageable, enucleation should be performed.

Medication

Broad spectrum antibiotics and systemic anti-inflammatory corticosteroids should be given at the time of surgery. Antibiotics and a tapering dose of steroids should be continued for 7-10 days after surgery.

Topical antibiotics and atropine should be used whilst the sutures are in place.

References

1. Giuliano, Elizabeth (2011) "Opthalmic Emergencies" Proceedings of the 2011 British Small Animal Veterinary Association Congress
2. Proptosis, The Merck Veterinary Manual 2013