Definition:

Proptosis is the forward displacement of the eye in the socket to become trapped in front of the eyelids.   

Anatomy/Physiology:

The eye is normally held in place by the extraocular muscles, soft tissues and eyelids to remain inside the bony orbit of the skull.  The optic nerve exits the back of the eye traveling to the brain. 

Clinical Signs:

The eye is prominent with the inability to blink the eyelids over the surface.  The tissues surrounding the eyes become very inflamed, preventing return of the eye to its normal position.  Bleeding inside of the eye and tearing of the muscles responsible for eye movement are common. Occasionally, there will be damage to the tissues surrounding the eye, either from the initial injury or from the patient following the incident. If the cornea is not lubricated, corneal ulcers are seen.

Causes:

Trauma is the most common cause, occurring after dog fights and car accidents.  Occasionally, the incident causing proptosis of the eye is not witnessed.

Examination:

Although the eye condition is unsightly, injuries such as head trauma, lung bruising or internal bleeding need to be stabilized before replacement is performed.  Assessment requires a complete physical exam, and in some cases radiographs. 

Surgery:

In all cases where there is the potential for vision, replacement of the eye into the correct position and suturing of the eyelids are recommended once the patient is stable for general anesthesia.  In some cases, an incision needs to be made into the eyelid to facilitate replacement.  The skin sutures are usually left in place for at least 2 weeks.  In cases where significant damage has occurred to the eye, removal of the eye may be recommended rather than replacement.

Prognosis:

Prognosis is related to head conformation and extent of damage to the eye and optic nerve.  Here are some criteria, in general:

            Better                                                              Worse

Dog with short noses (brachycephalic)            Cats and dogs with long noses

Signs of vision, light response                        Blood inside the eye (hyphema)

                                                               Globe rupture, retinal detachment

Long-term complications: 

It is uncommon for vision to be preserved, but many dogs can retain a cosmetic eye.  In some dogs, corneal ulcers occur, related to decreased corneal sensitivity from damage to the nerves supplying the cornea and/or decreased tear production.  Muscles controlling eye position can be torn, causing the eye to turn (usually outward).  Glaucoma from high pressure or shrinkage of the eye are also possible outcomes.  Proptosis can recur at a later time.

Revised 4/20/10