Dog And Cat Proptosed Globes
Proptosed globe may be the second scariest condition of pets after seizures.
Prominent-eyed dogs such as Pugs and Pekinese are prone to this condition, in which the eyeball itself pops out of the eye socket, usually as a result of trauma.
Proptosis is a Greek word meaning “fall forward.” Globe is a term ophthalmologists and general practitioners use to refer to the “eyeball.”
Precious Little Girl, a cute little five-year-old Pug, presented last week with her right eye hanging out of the socket. You can imagine the fear and anxiety the owners had. She, the other two Pugs and the Boston Terrier in the home had escaped under the fence and set out to terrorize the neighborhood. Instead, probably, they got terrorized and Little Girl’s injury probably occurred in a dog fight. She had a puncture wound on the left side of her neck consistent with a larger dog grabbing her and shaking her by the neck. She was lucky to even be alive.
All four dogs made their way home, and the other three were unhurt.
Proptosis can have several possible outcomes:
The best scenario occurred in Little Girl’s case, in which we were able to reduce the proptosis (put the globe back in place) without surgery. Step one is to generously lubricate the eye, as it has been devoid of tear protection while outside the eyelids. The dried cornea becomes very susceptible to damage. Step two is to at least lightly sedate the pet so that he, and his muscles, can relax. Some pets may require full general anesthesia at this point. Now the globe is gently but deliberately encouraged to return to its socket. One must have a feel for which eyes are candidates for this route of therapy. There are no fast guidelines and the unsure or novice practitioner should simply begin with scenario two.
If experience or failure at technique one leads a doctor to believe the globe cannot be reduced by that method, general anesthesia is a necessity. An incision is made at the lateral canthus, which is where the upper and lower eyelids meet on the side farthest from the nose. (The corresponding location close to the nose is the medial canthus.) This incision usually allows sufficient room to reduce the globe. After reduction the incision is closed with sutures.
Next comes the most frustrating part of dealing with a proptosed globe: the wait. Prognosing these eyes at the time of injury and reduction is usually very difficult. Prognosis involves two aspects:
Vision: Most proptosed eyes. even those without obvious, observable damage, are not visual at the time of reduction. That is, they have had too much shock to function and generate an image the brain can interpret. There are two main factors that determine whether vision will return to a proptosed eye. One is trauma to the globe itself. For example, if Little Girl had been bitten in the eye instead of the neck, a puncture wound would probably have ruined the eyeball permanently. The other factor is stretching of the optic nerve. Also known as cranial nerve II, it is one of twelve paired nerves that connect directly from the brain to its job site. As the optic nerve enters the eye and makes physical and electrical connection to the retina, it is a short and tight relationship. If the optic nerve is stretched too far its fibers can snap. They will not regenerate or reconnect. A great unknown can be, “How far did the optic nerve stretch?” If the globe is hanging down around the lip, we can be sure the nerve is stretched beyond repair. However, if the globe is tight to the eyelids, we have no way of knowing how far the nerve stretched, just to snap back almost to its correct location. That nerve is just as permanently damaged, but the evidence of the damage is not as obvious. Only time will tell us whether an apparently-good eye will provide vision in a week or two.
Saving the globe: Some eyes are obviously damaged beyond hope, as Little Girl’s might have been if punctured by a tooth. Huge lacerations and crushing injuries are also examples of eyes unlikely to be saved. An eye that has no vision may still have hope and usefulness. A healthy globe with a snapped optic nerve can still look good, move back and forth with the other eye and appear to be normal. While a heavily-damaged eyeball is clearly not worth saving, most people agree that one’s pet looks better with two globes than one, even if one doesn’t “work.” Your pet’s doctor will also evaluate damage to the extraocular muscles, which control the movement of the eyeball. They also have another crucial function, which is blood supply for the globe. It is generally accepted that rupture of three or more extraocular muscles will result in reduced blood supply to the eye and the eye will die and degenerate, just as any tissue cannot live without blood supply.
If the injured eye cannot be saved a procedure called enucleation is instituted. The globe is removed, the optic nerve is ligated and the lids are surgically permanently sutured closed by a procedure called tarsorrhaphy. Some pet owners elect to have a prosthesis made from manmade materials inserted into the socket to give the appearance of a globe being present underneath the surgical site.
Your pet’s doctor can evaluate your pet’s injured eye and recommend appropriate treatment. If he feels that specialty care is needed he can refer your pet to a diplomate of the American College of Veterinary Ophthalmologists.