Identifying Glaucoma in Dogs and Cats: Key Signs & Symp

What is Intraocular Pressure?

Intraocular pressure (IOP) refers to the pressure exerted by the fluid inside the eye. This fluid, known as aqueous humor, flows through a sievelike structure at the angle where the iris meets the cornea, and is then drained out of the eye. Normally, the rate at which aqueous humor is produced and drained is balanced, keeping the IOP in cats within a healthy range of 23.6 kPa. However, when the fluid's outflow is obstructed, the IOP can rise. High IOP can lead to the death of retinal cells, ultimately resulting in blindness.

Causes

Glaucoma is primarily categorized into two types: primary and secondary.

1. Primary glaucoma occurs without any preceding eye disease. This type is more common in certain purebred dogs.

2. Secondary glaucoma is a result of other eye conditions that affect the outflow of aqueous humor. The most common causes include eye inflammation, lens luxation, and eye trauma.

Common Symptoms

1. The cornea appears cloudy and the eye may appear larger.

2. The pupil may dilate or not respond to light.

3. The cornea may become cloudy or swollen.

4. Vision loss can occur.

5. The eye may bulge, become red, and swell.

6. Loss of appetite and depression.

7. Headaches and head shaking.

How to Diagnose

1. Medical History: Inquire about any previous medications or surgeries, and whether similar symptoms have been observed at home.

2. Visual Examination: Observe the conjunctiva for redness, the cornea for whiteness, and the eye for any abnormal protrusion.

3. Palpation: Press on the eye with your fingers to check for firmness.

4. Vision Testing: Assess the response to direct or indirect light stimulation.

5. Blood Tests: Routine blood tests and blood chemistry tests.

6. Intraocular Pressure Measurement: Normal IOP is between 23.6 kPa. An IOP between 2.74 kPa is considered moderately elevated, between 4.05.3 kPa is elevated, and between 5.36.7 kPa is significantly elevated.

7. Fundus Examination: Observe the optic nerve head for atrophy or indentation.

8. Gonioscopy: A procedure to examine the angle where the iris meets the cornea.

How to Treat

1. Medication: Acute glaucoma can be treated with intravenous infusions of hypertonic agents like mannitol to lower the IOP. However, glaucoma cannot be cured completely and requires regular IOP checks, typically every three months.

2. Surgery: In severe cases, an eye may need to be removed to alleviate pain caused by glaucoma in cats.