Acute development of glaucoma is a medical emergency and must be treated immediately, or permanent vision loss can occur. It can be treated medically or surgically. Medical therapy for glaucoma is generally very effective in the early stages, however with time and continued changes in the eye, medical therapy generally fails. Surgical therapy is the best option for potential long-term control of the pressure and maintenance of comfort and vision.
There are numerous medications used to help control glaucoma within the animal eye, including:
- Carbonic anhydrase inhibitors (dorzolamide, brinzolamide, methazolamide)
- Prostaglandin analogues (latanoprost, travoprost, bimatoprost)
- Beta blockers (timolol)
- And occasionally parasympathomimetics (demecarium bromide, pilocarpine)
These medications are often combined with pain medications, anti-inflammatory therapy and medications to help prevent continued damage of the retina and optic nerve after control of the pressure. As stated above, medical therapy is commonly effective in the short term, but generally fails in the long run, requiring higher and higher dosages of medications until the pressure is no longer manageable and vision loss occurs.
SURGICAL THERAPY TO PRESERVE VISION:
Surgical therapy to control glaucoma consists of procedures that increase the flow of fluid out of the eye (shunt procedures) and procedures to decrease the amount of fluid produced in the eye (laser surgery). Shunt procedures do not tend to have a long-term benefit alone, but are occasionally combined with laser surgery for long-term control. There are several types of laser surgery that can be performed, including micropulse laser therapy, transscleral laser surgery or endoscopic laser surgery. Your veterinary ophthalmologist will determine which laser therapy is best for your pet.
When blindness occurs secondary to glaucoma and the pressure is uncontrolled, there are several end-stage procedures that can be considered to provide comfort.
- The first procedure involves performing a painless injection into the back of the eye to lower the production of fluid within the eye. This procedure is effective approximately 85% of the time but can result in a decrease in the size of the globe, cataract formation and cloudy appearance to the eye.
- The last two procedures are surgical in nature and require general anesthesia. Enucleation is the complete removal of the globe and placement of a prosthetic within the orbit with the eyelids permanently closed. This procedure results in the most rapid control of the pain and the lowest potential for possible complications. Evisceration and intraocular prosthesis placement involves removing the internal contents of the globe and placing the prosthetic on the inside of the eye to result in a more normal post-operative appearance of an eye, but leaves the potential for problems with the surface of the eye such as ulcer formation or keratitis (inflammation of the cornea).