Glaucoma

What is glaucoma????
To put it simply, glaucoma is a lot like a plumbing problem.  There is fluid in the front of the eye that helps to keep the eye round.  This fluid, called aqueous, is produced by the ciliary body.  The ciliary body is situated behind the colored part of the eye, the iris.  This fluid must flow from behind the iris where it is made, come through the pupil, and then flow out of the eye through the “angle”, where it is then taken up by the blood stream.  This fluid is important because it not only provides support to the eye but also nutrition to the front half of the eye.

Glaucoma is always an obstruction of outflow of the fluid in the eye. Primary, or inherited glaucoma, occurs because the outflow area (angle) is not constructed normally and over the years, the angle narrows to the point that the fluid can no longer drain out of the eye.  This results in the fluid pressure building up over the normal level of 22mmHg.  Unfortunately, the eye continues to produce fluid even though it cannot drain out of the eye. This is a lot like having your sink drain plug up and your faucet is still dripping ---eventually the sink will overflow.  The eye cannot “overflow” but the eye pressure can build to the point of causing pain and nerve damage and eventual blindness if it is not caught in time and treated.  Most dogs will develop glaucoma in only 1 eye, at first.  However, because the eyes are made the same, the second eye will likely develop a problem within 6 to 18 months.

What can you do????
Unfortunately, glaucoma can occur so quickly in the first eye, that by the time the dog shows you there is a problem, it MAY be too late to save  vision for the first eye.  If vision cannot be saved then the next best thing is comfort for the blind eye.   During the office visit, Dr. Corcoran will evaluate the eyes and determine the chance of saving vision.  If vision is irreversibly lost then the client may have the choice of 3 procedures to attain comfort.  Two of the options would allow the dog to keep the eye and the third option would be to remove the eye.

Can we save vision????
The second eye has a much better chance of remaining visual (80%).  Not only is the client now fully educated about what glaucoma looks like in their pet, but the drugs to treat it will be ready at home for immediate use. In addition, if the dog can only see out of 1 eye, he/she will show you if there is a problem by bumping into objects.

Saving vision in a glaucoma eye initially entails using eye drops and sometimes glaucoma pills.  If the pressure spikes to the point of vision loss or continues to rise despite the use of medications then usually laser cycloablation surgery is recommended.  The diode laser damages the ciliary body cells to decrease the amount of fluid being produced.  This is a lot like turning down the dripping faucet so that the reduced amount of fluid being made will equal the reduced amount of fluid flowing out of the drain. Laser surgery is generally not a painful procedure.

How successful is laser surgery????
Laser cycloablation surgery success is not 100%, unfortunately, just like it is not in humans.   In Dr. Corcoran’s practice, the overall chance of saving vision is 80%, in the second eye that develops glaucoma.  

Would my pet need medications after surgery????
Usually, by the time dogs reach the point of needing laser surgery, they are on a fairly high level of medications; usually 2 to 4 different eye drops 3 times a day and glaucoma pills 2 or 3 times a day.  All of these medications can be given around an owners work/sleep schedule.  After laser surgery, the dog continues to need these medications and as he/she heals, the medications can usually be reduced significantly.

Would my pet need a 2nd surgery???? 
When laser surgery is performed, there is a limit to how many laser spots can be done at one time (usually 35-40 burn spots).  Once a dog heals from this (usually 3 weeks), there is a 25% chance a second laser will be needed, and a 5% chance a 3rd laser will be needed.  The time for additional lasers could be anywhere from 3 weeks to 2 years. The reason some dogs need these additional lasers is because we are limited on the amount of laser that can be done at one time.  The 2nd and possibly the 3rd add to the effect of turning down the dripping faucet a little more each time.

What happens day of surgery????        
Laser surgery is a fairly short operation as each laser spot is 1.5 seconds long and only 35- 40 are done. After laser surgery, Dr. Corcoran likes the dogs to go to Pender Emergency Service for overnight monitoring.  Due to post-operative inflammation, the dogs can sometimes have a pressure spike during the night.  The pressure can then be monitored by the emergency doctors and if needed, treated by the doctors to minimize nerve damage and maximize the chance of success. The following day, the dogs return to Vet Vision for a recheck and follow-up visits are scheduled depending on the dogs pressure readings and owners availability.  These post-ops are included in surgery fee for 4 weeks.

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