Under Pressure – Glaucoma in Your Pet
Thursday, March 01, 2018
Michele L. Edelmann, VMD, DACVO
Garden State Veterinary Specialists
Glaucoma is a common condition in dogs and cats that may be diagnosed by a veterinarian. Glaucoma is an increase in the pressure in the eye. The normal eye should constantly produce a fresh, water-based fluid at the same rate it drains out older fluid. In glaucoma, the drain of the eye is malformed and becomes clogged, but the “faucet” is still on, leading to pressure buildup.
The pressure buildup is painful. This may feel like a migraine headache. Furthermore, glaucoma may be blinding due to permanent damage to the delicate retina in the back of the eye.
Increased redness of the white of the eye, blue cloudiness, squinting, tearing, or rubbing/pawing at the eye may be appreciated. In some cases, an increase in size in the eyeball may occur to accommodate for the high pressure. Occasionally, no changes to the eye are noticed until vision loss occurs. This can happen very suddenly. Some owners notice that their pet seems quieter than normal or less interested in eating.
Ocular pressure may be measured by your veterinarian. This is a quick and simple test that is performed after application of a topical anesthetic eye drop in the office. Pressure should be lower than 25 mmHg. Pressure readings over 25 mmHg are consistent with a diagnosis of glaucoma. False high readings occasionally occur. If you or your veterinarian are suspicious that your pet may have glaucoma, referral to a veterinary ophthalmologist is recommended.
There are many possible causes of glaucoma. Cataracts, chronic inflammation (uveitis) in the eye, ocular tumors, trauma, and retinal detachments are just a few causes. A complete eye examination with an ophthalmologist can help determine the cause. In some cases, no obvious underlying cause is found and a genetic tendency towards glaucoma is suspected. This is called primary glaucoma. Primary glaucoma is a disease that will also affect the opposite eye, typically within 6 months to 1 year after the original diagnosis. For this reason, the ophthalmologist may recommend that your pet be treated prophylactically in the opposite eye to delay the onset of disease.
The first line of treatment for glaucoma is eye drop therapy. Your ophthalmologist can prescribe medications to help to reduce pressure in the eye to restore comfort. In some situations, your ophthalmologist may recommend laser surgery. This procedure is performed under general anesthesia. A laser is used to inactivate the parts of the eye that produce fluid. Your pet may also be a candidate for shunt placement (“Ahmed valve”). This is an implant that improves fluid drainage out of the eye. The goals of laser/shunt surgery are to lower pressure more permanently, to reduce the need for topical medications, and to maintain vision for as long as possible.
If your pet is suspected to be permanently blind and medications are not effective in keeping pressure to a comfortable range, there are additional procedures or surgeries that can be discussed to restore comfort.
This article is for informational purposes only and should not be used as a substitute for the professional advice of your veterinarian.
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