August 16, 2016
Somewhere along the way your children catch on to you and become very suspicious when you are happy about something. Mine questioned the origin of names I kept pressing upon them for new pets. They obstinately refused to name the new cat “Tenesmus”. C’mon, I begged, it sounds great, doesn’t it? What does it mean? they questioned. Surly attitude! When I confessed tenesmus meant “straining to defecate” they did not laugh. I told them no one else would know. “No, Mom”, they said.

I have another favorite : Buphthalmia. Yes, it sounds like a long burp! Is there anyone else out there who only burps after drinking root beer? I digress. So what is “buphthalmia”? Pronounce it “bup” then add “thal-mee-ah”. It was an ophthalmologist, an eye doctor, who coined this word. Spelling that ph-th thing was the first question on our opth exam back in vet school.

Buphthalmia is different than exophthalmia. Exophthalmia is when the eyeball bulges out of the orbit, pushed behind by a space-occupying lesion like a blood clot or a mass. Buphthalmia is a little different : you will see an enlarged eyeball, bigger and wider than normal, because the cornea and surrounding tissues covering the eyeball have been stretched out by fluid build-up inside the eye.

The eyeball is nestled safely inside a protective ring of bones, often collectively referred to as the eye socket or orbit. The eye is an amazing organ and provides one of the five major senses, sight. The eyes of many animals have specialized features that allow them to see underwater, see in the dark, reflect light, and see in color. Most mammals and many birds and reptiles have a third eyelid which slides over their eyeball to both protect and lubricate the eye. Humans lack a third eyelid. It slides up from inside the inner lower corner of the eye, near the nose, and may be light pink in color. The inside of the eye is constantly bathed in a gentle fluid, the aqueous humor. This fluid circulates in front of the lens and helps to keep the eyeball round. The fluid pressure provided by the aqueous humor can be measured as intra-ocular pressure or IOP. If you, a human, has ever seen an eye doctor, they have probably measured your IOP with a tonometer – a little puff of air directed straight at the center of your cornea. We also use tonometry in veterinary medicine. Why do we care? Because the fluid in the front of the eyeball can build up, creating too much pressure. Too much pressure inside the eye is diagnosed as GLAUCOMA. This often happens because the aqueous humor doesn’t drain away properly. Once clogged, through a disease process or even an inherited problem of narrow drainage, the fluid builds up, creating pressure on the outer eyeball membranes and cornea which spread and bulge. The eye may look red or bluish and the pupils may dilate. Once the eyeball has enlarged, called buphthalmia, there is no going back. The eyeball will never return to its original size.

Your pet has an emergency. Without immediate medical treatment, in as little as a couple of hours the sustained high intraocular pressure can lead to blindness. If only one eye is affected by glaucoma the other may be at risk. Buphthalmia is a classic sign of glaucoma. Once diagnosed, the remaining Healthy eye should be treated with preventative eye drops for the rest of the pet’s life.

Certain breeds are predisposed to glaucoma, though the largest category is “mixed breed”, so no dog is safe. Cocker Spaniels, Bassets and Beagles, Boston Terriers and Norwegian Elkhounds all make the list. I’ve seen it in a family of Bouviers, an Akita and in Jack Russell Terriers. One day the owner notes their dog’s eye is a little cloudy and the next day as they come in for their appointment it is bulging and blood shot and ugly. It is too late to save the eye. A blind, painful eye requires enucleation or removal, for humane reasons. Thankfully, many eyes can be saved by prompt attention and treatment.

Christine B. McFadden, DVM
drmc@mcmenagerie.com