Information on cats and dogs with glaucoma and lower canine and feline eye pressure.

What is Glaucoma?

Glaucoma is when the pressure of the fluid or aqueous humor within the eye becomes excessively high. This is a serious eye condition that can affect your pet and cause long term damage if left untreated. As the pressure within the eye increases, pressure is placed on the optic nerve and as a result visual impairment and even blindness can occur. Although the condition can affect both, glaucoma tends to be far more common in dogs than cats.

The symptoms of glaucoma may include the following:

• Severe pain in the eye (while pets cannot tell us about their pain, they may communicate it to us in their behavior. Pain often causes irritability, poor appetite, or lethargy)
• A yellow-green discharge from the eye
• Reddened eye
• Enlargement of the blood vessels of the sclera or whites of the eyes
• Impaired vision
• Clouded cornea or an eye with a bluish tint
• Dilated pupils that don’t constrict with light
• During later stages of glaucoma the eye may appear larger or bulging.

What Causes Glaucoma?

The eye constantly produces aqueous humor, (the clear fluid that fills the anterior chamber of the eye) and this aqueous is steadily filtered out of the anterior chamber through a complex drainage system. When this drainage system becomes too slow, or for other reasons, the aqueous builds up in the eye, the eye’s intraocular pressure (IOP) increases and pressure is put on the optic nerve and retinal fibers.

Glaucoma can either be primary or secondary. Primary glaucoma is when glaucoma occurs as your pet has a physical predisposition to the condition. For example, drainage pores within the eyes may be too small, or at an awkward angle, making drainage of fluids from the eye difficult. In many cases primary glaucoma is genetic and is commonly seen in certain breeds such as Beagles, Cocker Spaniels, Basset Hounds, Miniature Poodles and Dachshunds.

Secondary glaucoma on the other hand is caused by another condition such as an eye inflammation caused by injury or an eye infection, cataracts, cancer in the eye, lens displacement, or chronic retinal detachment.

Diagnosing Glaucoma

If you suspect your pet may have glaucoma then it should be treated as a veterinary emergency. Your vet will measure the intra intraocular pressure (IOP) with a Schiotz tonometer or a Tonopen. Normal IOP readings range between 12 to 22mmHg, and a reading of greater than 30mmHg is generally diagnosed as glaucoma.

Help for Glaucoma

The treatment of glaucoma depends on the severity and the underlying cause of the condition. In many cases, by the time the glaucoma is realized, permanent visual damage has already occurred and the treatment is aimed at saving the unaffected eye. Therefore the sooner the glaucoma is treated, the better the prognosis.

Conventional treatment options include medication or surgery. There are a number of medications that can help to reduce intra intraocular pressure, reduce the amount of aqueous humor produced in the eye, and assist with fluid drainage. These may include topical ointments or oral medications, however it must be noted that medication is usually not a long term solution to the problem, and in many cases, glaucoma is only resolved with surgery.

Surgical procedures will vary depending on the cause and severity. In a procedure known as laser cyclophotocoagulation, a small part of the eye that produces the aqueous humor is destroyed to reduce fluid build up. In cases where the eye is very painful, or visual damage has resulted in blindness, the eye is often removed in a procedure known as enucleation.

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