Glaucom
Glaucoma diagnosis refers to elevated intraocular pressure. Normal intraocular pressure values are:
- In dogs: 10-23 mmHg
- In cats: 10-25 mmHg
If the intraocular pressure is higher than this, it is referred to as glaucoma.
Why does intraocular pressure increase?
Intraocular pressure rises when the drainage of fluid circulating within the eye (aqueous humor) is impaired. There are two main types:
- Primary glaucoma: develops due to congenital or age-related drainage problems.
- Secondary glaucoma: other eye diseases (e.g., tumor, inflammation, lens luxation) obstruct the drainage of aqueous humor.
Primary glaucoma
An inherited condition in certain dog breeds that appears at 3-7 years of age, initially affecting one eye, but eventually also affecting the other eye.
The most commonly affected breeds are:
- Alaskan Malamute
- Basset Hound
- Cocker Spaniel
- Chow Chow
- Samoyed
- Siberian Husky
- Shar Pei
- Hungarian Vizsla
Secondary glaucoma
The drainage of aqueous humor is obstructed by another eye disease, such as:
- Chronic internal eye inflammation (uveitis)
- Displacement of the lens (lens luxation)
- Tumor in the eye
Does glaucoma cause pain?
In some cases, intraocular pressure rises quickly (within hours), causing severe pain, which in humans is compared to a migraine-like headache.
If the intraocular pressure rises slowly (over years), animals experience mild or no pain.
How do I know if my dog/cat has glaucoma?
Symptoms of sudden-onset glaucoma:
- Strongly reddened eye
- Squinting
- Tearing
- Dilated pupil
- Cornea becoming opaque (bluish in color)
- Lethargy, loss of appetite, occasionally aggression
Symptoms of slowly developing glaucoma over time:
- Deterioration of vision
- Enlargement of the eyeball
- Cloudy eye surface
- Occasionally a strongly reddened eye
- Animal's general condition remains unchanged
Why is glaucoma harmful to the eye?
High intraocular pressure presses on the retina and optic nerve, which can cause permanent damage within as little as 24-48 hours. For this reason, glaucoma is considered an emergency that requires immediate treatment.
How is glaucoma treated?
The goal is to reduce intraocular pressure as quickly and durably as possible:
- Immediate treatment: a combination of infusion, tablets, and eye drops
- Long-term treatment: eye drops that reduce the production of aqueous humor and help its drainage
Regular and precise administration of the eye drops is essential for the success of treatment.
What happens if medical treatment is not enough?
If eye drops are not effective, various surgical solutions can be used:
- Laser or cryotherapy procedure: destruction of the cells that produce aqueous humor
- Glaucoma implant: implantation of a device that drains the aqueous humor
Unfortunately, these methods do not always work in the long term, and animals eventually lose their vision.
What can I do if my dog/cat has gone blind due to glaucoma and is in pain?
If the eye is causing pain, the following solutions are possible:
- Removal of the eyeball (enucleation) – after the skin is sutured, the fur covers the site of the eye
- Intrascleral prosthesis – after removal of the eye's interior, a silicone sphere is implanted
- Medical treatment (gentamicin injection) – can be used in dogs, but in cats it can cause tumors, so it is not recommended
What is the prognosis for glaucoma?
If the disease is recognized in time, treatment can be effective, but in the long term the intraocular pressure often rises again, which ultimately leads to blindness.