Secondary Glaucoma due to Lens Luxation in a Dog

I did a post on glaucoma over on the pet insurance blog last summer. It was basically an overview of the disease process and potential treatment options. Interestingly, I got an e-mail from a reader with a dog that has glaucoma. It was thought provoking and merits general discussion.

There are two broad classifications with glaucoma. Primary glaucoma is due to a defect in the eye's drainage system and tends to be inherited. Secondary glaucoma is also the result of poor fluid drainage from the eye but the defect is due to some other issue. For instance, a tumor may be present that disrupts the outflow of aqueous humor and the resulting increase in intra ocular pressure is secondary to the presence of the tumor.

 

Another form of secondary glaucoma is due to something called lens luxation. The lens is the structure in the eye that helps us focus. Cataracts form in the lens resulting in clouding and loss of sight. The lens is held in place by fibers that attach to the inside of the eye. In certain breeds these fibers break down prematurely and the lens is no longer anchored in place. In some cases it flops around in the front part of the eye and it can interfere with the drainage system resulting in secondary glaucoma.

 

Lens luxation can be the result of trauma but more commonly, it, too, is an inherited defect. Lens luxation is more common in Border Collies, Brittany Spaniels, and many terrier breeds. In fact, our reader has a Wheaten Terrier that has glaucoma secondary to lens luxation. 

 

She had been to see a veterinary ophthalmologist and he had recommended surgery to remove the lens to correct the glaucoma. Her dog was receiving medical treatment for the pressure build up and she wanted to know my opinion on the surgery. 

 

It's really a matter of timing and the potential for preserving some sight in the eye. High intraocular pressure can do irreversible damage in as little as a few hours.

 

My assumption, in this case, is that the ophthalmologist assumed there had not been irreversible damage due to the glaucoma. In that case the surgery is really the only hope. If you don't remove the cause of the outflow problem you don't have a real chance of preserving the eye and some vision. It doesn't make much sense to treat a problem medically when the cause is a physical blockage that could be removed surgically.

 

There are no guarantees. though. All surgery involves risk and the outcome is not guaranteed. In this case it seems that the risk of surgery is justified.