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Glaucoma in dogs treatment
Canine Glaucoma is a condition that affects the eye (visual field), causing permanent damage to the optic nerve (optic nerve is a long, thin nerve that connects the eye to the brain). There are two main types of Glaucoma in dogs, Open-angle Glaucoma (OAG) and Angle-closure Glaucoma (ACG), the two can co-exist.
Signs &, Symptoms
Signs of glaucoma are progressive, with blindness occurring in about half the affected dogs. As glaucoma progresses, vision may be affected in the same way as when cataracts progress from a mild clouding to complete blindness, from decreased to loss of light. Early signs may include:
Increased intraocular pressure (IOP): Dogs with normal IOP may develop glaucoma with age, but most cases of glaucoma are due to a primary condition that is not associated with normal IOP. If your dog is having glaucoma for the first time, a pressure measurement will be needed to determine whether it is possible to control the IOP.
A dilated and hyperemic pupil: Dilated pupils are often seen in dogs with glaucoma, but a slightly enlarged pupil may be seen due to the increased IOP. This may also be caused by a drug that has been prescribed. Other factors that may affect pupillary size are the size of the dog, ambient lighting and drugs that affect the pupillary muscles.
Ocular hyperemia: Ocular hyperemia (redness) is a result of an increased blood flow to the eye. This may also be caused by a drug that has been prescribed.
Narrowed and irregular pupils: The diameter of a dog's pupil is affected by the amount of light entering the eye and the pupil's reflex to change size to allow more light in or less light out. Drugs that affect the size of the pupil are the most likely cause for narrow or irregular pupils.
Glaucoma is considered a secondary disease in some cases, with the primary disease resulting in a significant increase in IOP. Examples of these primary diseases include:
Narrowed angle: Dogs with a narrowed angle will have a small opening between the iris and the cornea, and will require a surgical treatment.
Necrotizing episcleritis: Dogs with a secondary (or undetermined) cause of angle closure that result in increased IOP and corneal edema will often need an episcleral (or extraocular) glaucoma surgery.
Uveitis: An inflammatory eye disease that results in swelling, redness, pain, and discharge from the eye.
Uveitis can be diagnosed by a veterinarian with a slit lamp. Glaucoma is most often secondary to uveitis, with the inflammation of the iris resulting in an increased IOP and angle closure.
The most common glaucoma treatment for dogs involves medical therapy (medications) and surgery.
The main goals of glaucoma treatment are to:
Prevent visual field loss
Slow or prevent blindness
Treatment of Glaucoma
Glaucoma treatment usually begins after an initial diagnosis has been made. Initial treatment includes controlling IOP and other medications are usually prescribed to manage secondary conditions. In addition, medications are usually prescribed for long-term therapy to control IOP and prevent further disease progression.
Eye drops: Eye drops are the primary form of medication for dogs with glaucoma. Glaucoma eye drops contain a drug that lowers the IOP.
Topical corticosteroids: Topical corticosteroids are used to reduce inflammation, and are administered daily (to the eye) or as needed. They are not considered to be an effective treatment for glaucoma.
Beta-adrenergic receptor blockers: These drugs are sometimes prescribed to control increased IOP. Beta-adrenergic receptor blockers, such as Betaxolol, can be used alone, or in conjunction with other therapies. They may be the best treatment option for dogs with glaucoma that is unresponsive to other therapies.
Antiglaucoma surgery: Glaucoma surgery is performed to widen the drainage angle and/or remove abnormal tissue, and may be performed in combination with other procedures. Surgical treatments are not always successful, and will often be performed in conjunction with medication. A glaucoma drainage device (GDD) may be used as an alternative to glaucoma surgery in dogs that have not responded to medications.
Laser iridotomy: Laser iridotomy has been used as a primary treatment for angle-closure glaucoma. It may be used alone or in conjunction with glaucoma medications. Laser iridotomy is a temporary treatment that usually only lasts a few days.
Episcleritis surgery: Episcleritis surgery is usually performed when other treatments fail. It is considered a surgical procedure that usually lasts several weeks, although it may take longer. Surgery may be used alone or in conjunction with glaucoma medications.
What to Expect
Glaucoma treatment may be long-term (years), and involves the administration of a number of medications, and potentially surgical treatments.
Treatment is often started after an initial diagnosis of glaucoma has been made. The prognosis for dogs that have glaucoma depends on:
the type of glaucoma
the severity of the disease
the effectiveness of the treatment
In many cases, glaucoma will progress despite treatment, and it will become more difficult to control IOP, leading to further vision loss. It is often necessary to perform repeated treatments for many years. Dogs that have a severe, non-responsive form of glaucoma are less likely to respond to treatment.
Treatment options are usually not considered until other treatments have been unsuccessful in controlling the increased IOP, or if IOP is