Iris Cysts in Dogs

An iris cyst is also commonly known as a uveal cyst. It most cases, it is a hollow structure that appears on your dog’s eye for any number or reasons. It does not hurt your dog nor does it cause any issues. However, in rare cases, it can lead to a change in behavior due to change in vision or it may obstruct the eye drainage system and can lead to related complications. If it is not causing your dog any problems, you may not have to do anything to correct it. If it is causing problems for your dog, certain veterinarians can perform some type of surgical correction. If your dog does have surgery, he can recover well with proper rest and treatment.

An iris cyst is common in dogs.  Dogs can be born with them, they can develop them after some form of trauma, or they can just appear with no known cause.  If your dog has one of these, no need to be alarmed.  In most cases, if does not affect your dog whatsoever.

Most iris cysts do not cause symptoms in dogs.  However, the possible symptoms it could cause include:

• Vision alteration
• Obstruction of the drainage angle of the eye
• Change in behavior 
• Eventual development of glaucoma

Types

The iris is the circular pigmented membrane behind the cornea and perforated by the pupil. This means it is the colored part of your dog’s eye.   A cyst, by definition, is an abnormal closed cavity that contains liquid or semi-solid material, lined by epithelium, and located somewhere in or on the body.  Iridic cysts in dogs are typically free floating, pigmented spheres within the anterior chamber, posterior chamber, and pupil.

Iris cysts are commonly seen as a secondary effect of inflammation of the eye. Out of all the animal species, they are the most common in dogs. The cause of an iris cyst can also be from some form of trauma of the eye or it can be a congenital cyst that the dog is born with. But in most cases, the cause is unknown.

For the veterinarian to get a proper evaluation of your dog’s eye, there are multiple tests she may perform. The first test she will perform might be a Schirmer Tear Test (STT). This test evaluates the moisture the eye is able to produce by measuring the tear production. Without proper moisture, the eye can develop a number of medical issues including ulceration and dry eye. 

Fluorescein staining may be the next test performed. The sodium fluorescein stain used will bind to unhealthy parts of the corneal stroma. If there is any blotting in the distribution of the stain, it is indicative of an abnormality. With the stain on the affected area, the veterinarian will be able to evaluate the problem easier and more thoroughly.

Another test the veterinarian may perform is tonometry. This determines the intraocular pressure (IOP), also known as pressure inside the eye. This is typically used when evaluating for glaucoma, but in this case it can be used as a rule out diagnostic test. For more in depth tests, you may have to go to a specialist. They will be able to perform an ocular ultrasound, aesthesiometry, or an electroretinogram if needed.

Iris cysts rarely cause vision impairment so most cases do not need medical correction. If it does impair his vision, your dog may need surgery to aspirate it or to have it surgically removed. In most cases the cyst is typically a free floating hollow structure that causes no side effects. If your dog does need surgical correction, you will need to take him to a specialist. Eyes are very delicate and most general veterinarians do not have the amount of experience the specialists do.

If the iris cyst is not causing any issues for your dog and therefore no treatment is needed, your dog will probably be just fine. However, if he did get some type of surgical correction, recovery is pretty straight forward. Depending on what procedure was performed, your dog will need to be on kennel rest for the first week or so to ensure he doesn’t accidentally hurt himself. His eye may need to be covered until healed so he will need a little time to adjust to his temporary one eye view. 

He may also be sent home with medications specifically for his eye and for his system overall. He may need eye drops or ointment for a little while to ensure proper lubrication of the eye. He may also receive antibiotics as a precaution to prevent infection from developing and pain medication to help with any inflammation or irritation. Every veterinarian has their own protocol they like to follow and will recommend specific medications to send home with your dog. 

In most cases, dogs recover very well from development of an iris cyst. As stated earlier, since they typically do not cause problems, surgical correction is not recommended unless there is an issue. Since the eye is such a delicate instrument, the less treatment needed, the better.