What is glaucoma?
Glaucoma is elevated eye pressure that can lead to blindness by damaging the retina and optic nerve. Normal eye pressure is on average 15-20 mm Hg for the dog and cat. When eye pressure is elevated above normal and evidence of ocular damage in the eye is occurring, glaucoma is present.
What are the clinical signs of glaucoma?
Blindness that may be temporary or permanent, red eye (a bloodshot eye), and a blue/white haze to the surface of the eye from excess fluid in the cornea (corneal edema).
What causes glaucoma?
The eye continuously makes fluid (aqueous humor) to provide nutrients to the eye and maintain intraocular pressure. This fluid is drained from the eye continuously as well to maintain the balance. When fluid cannot be drained from the eye fast enough, glaucoma occurs.
Glaucoma can be a primary (inherited disease) that runs in certain breeds (Cocker spaniels, Beagles, Basset hounds, Chow chow, Sharpeis and many others). When that is the case, we may examine the drainage angle (iridocorneal angle) of the eyes as part of our glaucoma assessment.
Glaucoma can also be caused by another eye disease like a tumor growing in the eye, internal eye inflammation (uveitis), blood in the eye (hyphema), or a lens being misplaced into the front portion of the eye (anterior lens luxation). Uveitis is the most common cause of glaucoma in cats and horses.
Treatment of the underlying disease is essential to success in treating the glaucoma.
What are the consequences of glaucoma?
Glaucoma is a blinding disease in which the high eye pressures destroy the retina and optic nerve. Glaucoma can also cause internal eye inflammation (uveitis) and other intraocular problems like luxated lenses.
What is the prognosis for vision with glaucoma?
Acute (short term like a day or two) glaucoma can often be treated so that vision is restored for some time.
Chronic (long standing) glaucoma usually results in permanent blindness and will cause the eyeball to physically enlarge (buphthalmos).
The prognosis for vision varies a great deal from animal to animal. The short term prognosis, therefore, is variable. The long term prognosis for vision is poor but vision may be retained for many years with appropriate management.
How is glaucoma treated?
Aggressive treatment in sudden, short-term glaucoma may restore vision. In animals with some vision remaining, treatment usually consists of long-term medications to control the eye pressure.
Laser surgery may improve long term control of eye pressure in addition to medications. The laser energy is used to reduce the number of fluid making cells (cycloablation).
Surgical shunts can also be placed to drain the excessive fluid from the eye.
Glaucoma is a disease that is controlled and not cured, and usually worsens with time.
In animals with permanent vision loss, treatment is still needed to provide long term comfort because glaucoma can be uncomfortable (a deep headache). Treatment can be medical or surgical (laser, intraocular prosthesis, enucleation) to maintain comfort. With some of these procedures, a cosmetic and comfortable eye can be maintained.
We will discuss the various treatment options and long term prognosis for your pet's vision with you after the eye examination.