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Degeneration of the Iris in the Eye in Dogs / Iris Atrophy

What Is Iris Atrophy in Dogs?

Iris atrophy in dogs refers to a condition where the iris muscle, responsible for regulating the size of the pupil, undergoes thinning. Analogous to a camera, the iris adjusts the pupil size to control the amount of light entering the eye. In bright conditions, the iris constricts the pupil; in dim environments, it dilates the pupil to maximize light intake. The iris, visible as the colored part of the eye, may exhibit irregularities due to atrophy, appearing misshapen or moth-eaten.

Primary iris atrophy, the more prevalent form, typically manifests in older dogs. Conversely, secondary iris atrophy occurs when inflammation increases pressure within the eye, leading to muscle thinning.


Symptoms of iris atrophy in dogs can vary, and some dogs may not exhibit any noticeable signs. However, sensitivity to light can develop as the iris loses its ability to adequately close the pupil in brighter environments. Additionally, in cases of secondary iris atrophy, you may observe your dog squinting or winking more frequently as a response to discomfort.


The primary cause of (or geriatric) iris atrophy in dogs remains unknown. It often occurs spontaneously as part of the aging process, without any specific identifiable cause. While small toy breed dogs might have a higher predisposition, iris atrophy can affect dogs of any breed.

In certain instances, uveitis, characterized by inflammation of the uvea layer in the eye, can lead to iris atrophy. Uveitis can stem from various factors, spanning from systemic diseases to ocular trauma.


Veterinarians commonly diagnose iris atrophy during routine ophthalmology examinations. Using a light source, they inspect the eye for irregularities such as holes in the iris or abnormal pupil shapes. Additionally, vets may conduct a pupillary light reflex test by shining a bright light into the eye to observe the pupil’s response. Any abnormal or delayed reaction may indicate iris thinning.

If there’s suspicion of an underlying condition like uveitis or glaucoma, your vet may conduct further diagnostic tests. In cases where trauma might be a contributing factor to iris atrophy, X-rays may be recommended to assess the extent of injury.


Treatment options for primary iris atrophy in dogs are limited, as it is a natural aspect of aging and cannot be reversed. Fortunately, in many cases, primary iris atrophy doesn’t significantly impact a dog’s vision, though they may experience increased sensitivity to light.

On the other hand, secondary iris atrophy requires treatment aimed at addressing the underlying cause, typically uveitis or possibly glaucoma. By treating the underlying condition, veterinarians can help manage secondary iris atrophy effectively.

Living and Management

Dogs affected by iris atrophy can generally maintain normal lives. Unfortunately, there’s no known method to stop the advancement of the condition, though it seldom results in noticeable symptoms.

Iris Atrophy in Dogs FAQs

Is iris atrophy painful for dogs?

No, iris atrophy does not cause pain for dogs.

Can iris atrophy in dogs be corrected?

Iris atrophy in dogs cannot be treated or corrected.

Will a dog become blind due to iris atrophy?

Iris atrophy does not lead to blindness. While the dog’s eye may have challenges adjusting to light changes, it does not impair the dog’s overall vision.

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