Written by Vet

Iris Bombe In Dogs: Symptoms, Causes, and Diagnosis

  • Written by:Dr. Margarita Boyd, BVSc MRCVS
Iris bombe is a health condition commonly seen in both dogs and cats. When it comes to dogs, any breed can be affected by this condition. Moreover, it can appear in dogs of any size and age. Discover why the Iris bombe is a serious condition and how it can affect your dog's health.

Iris bombe occurs when the iris, the circular colored ring of the eye, becomes abnormally attached to other parts of the eye.

It’s most common for the iris to get stuck and form adhesions to the lens of the eye.

Iris bombe in dogs is a serious and painful condition, which can quickly cause irreversible damage to the dog’s eye or even result in blindness. An affected dog will often have a red, sore eye which may appear to bulge out more than normal.

In this article, we will take an in-depth look at the iris bombe in dogs, including the symptoms, underlying causes, diagnosis, and the treatment options.

We will also learn a little about the normal structure of the dog’s eye and cover some common eye terminology, so you can be fully knowledgeable about your dog’s eyes!

If you think your dog is showing signs of a painful eye or is suffering from the iris bombe condition, then you should take him to your veterinary clinic immediately. Unfortunately, eye problems can be pretty serious!

The Normal Dog Eye

A dog’s eye looks and functions in a very similar way to a human eye. The eye is able to adjust the amount of light that it lets in, focus on objects and constantly send messages to the brain to allow vision. That is pretty amazing, right?!

The MSD vet manual provides a lot more detail on the anatomy of the dog’s eye if you want to read more about it. Some of the basics include:

  • Light passes through the cornea, the transparent front layer of the eye.
  • The iris is the circular, colored part of the eye. It controls the amount of light that enters the eye by making the pupil larger or smaller.
  • The pupil is the black area in the middle of the eye. When it’s dark, the pupil gets bigger to let in more light; when it’s bright the pupil becomes smaller, to let less light in.
  • The lens sits behind the iris and can change shape to help focus light onto the special layer at the back of the eye called the retina.
  • The retina contains special cells that sense light and allow the dog to see images.
  • The optic nerve sends electrical signals from the retina to the brain, to allow the dog to see.

What Is Iris Bombe?

Iris bombe is a painful condition caused by abnormal adhesions, or synechiae, between the iris and other parts of the eye.

The iris can either move forward and attach to the fluid near the cornea or more commonly move back slightly and become attached to the lens of the eye.

The most common presentation is when the iris becomes fully stuck to the lens all around the pupil border, causing the iris to change shape and bow forward slightly.

These changes can prevent the normal movement of fluid within the eye, causing a blockage and build-up of pressure. The increase in pressure within the eye is known as glaucoma, a serious consequence of iris bombe in dogs.

Symptoms Of Iris Bombe In Dogs

The signs of this condition can vary from dog to dog, but the condition becomes more serious and obvious the longer the dog has had the condition. Common signs of iris bombe in dogs include:

  • Squinting or keeping the eye closed
  • Corneal ulcers
  • Excessive tears
  • Change in the iris color or appearance
  • Change in pupil shape
  • Eye appears cloudy
  • Eye appears red and inflamed
  • Decreased sight/bumping into things
  • Decreased reaction to light
  • Blood vessels on the whites of the eye
  • Rubbing the eye
  • Eye appears bigger or bulging

What Causes Iris Bombe In Dogs?

The adhesions between the iris and the lens can be caused by a variety of different conditions. Usually, they are caused by inflammation or an increase in pressure within the eye.

Inflammation is part of the body’s normal response to harmful stimuli, such as bacteria, viruses, irritants, foreign bodies such as wood splinters, trauma or injury.

It’s a protective response to bring lots of immune cells, white blood cells, and blood vessels to the area to eliminate the cause of the inflammation, get rid of any damaged cells and try to repair the tissue.

Let’s take a look at some common causes of iris bombe in dogs:

1. Uveitis

The uvea is part of the eye made up of the iris, the ciliary body (produces the fluid inside the eye) and the choroid (the dark middle layer of the eye).

Uveitis is an inflammation of one or all of these structures and is a common cause of iris bombe.

Uveitis in dogs has many different causes including bacterial, viral, fungal or parasitic disease, diabetes, injury to the eye, cancer, high blood pressure, or sometimes the cause is never identified (idiopathic).

2. Trauma

Iris bombe may develop after the dog has had a trauma or eye injury. Common injuries include cat scratches, or foreign objects piercing the eye such as wood splinters or broken glass.

3. Glaucoma

Iris bombe may develop due to glaucoma in the dog’s eye. Glaucoma is an increase in the intraocular pressure inside the eye, leading to damage to the retina and optic nerve, and possible blindness.

4. Infection

Infection within the eye may be caused by bacteria, viral, fungal or parasites. They may enter the eye from a scratch or trauma on the cornea, or from the inside of the body via the bloodstream.

If the iris becomes inflamed or damaged, then the iris bombe condition could occur.

5. Surgery

Unfortunately, the iris bombe may occur as a possible complication following eye surgery. An example of common eye surgery in dogs is cataract surgery, and the iris bombe is a possible complication of this procedure.

A cataract is an opacity or whiteness of the lens, which often causes blindness in dogs.

6. Lens Luxation

Lens luxation is when the lens moves out of its normal position and moves either forward or backward. If it moves forward it can become abnormally attached to the iris.

How Is Iris Bombe Diagnosed In Dogs?

A veterinarian will make a diagnosis of the iris bombe after completing a full clinical examination of your dog. Usually, the vet will use a few tools to help them examine your dog’s eyes including:

Ophthalmoscope

This handheld device allows the vet to shine a light into your dog’s eyes, and change the magnification, so they can check different parts of the eye including the cornea, lens, iris, and retina.

During this examination, the vet will check the appearance, color, and location of the iris.

Tonometer

A tonometer is a small pen-like device used to measure the intraocular pressure in your dog’s eyes. It won’t hurt your dog and it is simple for the vet to perform. The intraocular pressure will be higher than normal if your dog has an iris bombe.

The normal pressure inside a dog’s eye is usually between 15-25 mmHg. Higher intraocular pressure than normal is a sign of glaucoma, can quickly cause blindness in dogs.

Fluorescein

Fluorescein is a bright yellow/green dye that is used to check for corneal ulcers or abrasions on your dog’s eyes. The vet will place one drop of this stain in each of your dog’s eyes and then use the ophthalmoscope to check the cornea.

Schirmer’s Tear Test (STT)

The STT checks the levels of tear production in the eye. This allows the vet to check if the dog is producing a normal tear film, or if the eye is drier than normal.

This test involves placing a small strip of special filter paper in the lower lid of the dog. It won’t hurt at all, but obviously some dogs may need a bit of comforting and encouragement.

Other Tests

The vet may recommend other tests to check the overall health of your dog including routine blood tests, urinalysis, ultrasound of the eye or x-rays. These will help to rule out other underlying problems.

How Is Iris Bombe Treated In Dogs?

The treatment options will vary depending on the severity of the signs and the underlying cause of iris bombe, but some common options include:

Pain Relief

Iris bombe is thought to be a painful condition therefore the dog will benefit from some pain relief. This is often given as an injection in the vet clinic and the dog may be prescribed pain relief medication in the form of tablets or liquid to take at home as he recovers.

Topical Corticosteroids

Topical corticosteroids work well to reduce inflammation in the eye, e.g. in cases of uveitis. These eye drops will need to be applied regularly to the dog’s affected eye.

They should not be used if the dog has a corneal ulcer present or an infectious cause of inflammation in the eye, as they may prevent healing and make infections worse!

Antibiotics

If the dog has a bacterial infection in the eye(s), or the dog is at risk of developing one, then topical or oral antibiotics may be advised.

You should try to strictly follow your vet’s advice on how frequently to give antibiotics, and it is important to finish the full course.

Glaucoma Treatment

If a dog has glaucoma (elevated intraocular pressure) then a topical eye drop or oral medication will be used to try to decrease the pressure inside the eye.

If a dog with glaucoma doesn’t have treatment, then he will probably quickly go blind. Surgery may be required for better long term control of this condition.

Surgery And Laser Treatment

Surgery or laser therapy may an option to remove the adhesions which form in iris bombe, between the iris and the lens.

Iridotomy, surgical removal of part of the iris, may also be necessary in severe cases. In cases of lens luxation, the lens is usually surgically removed or a less invasive approach using ultrasound to break down the lens may be offered.

These types of complicated procedures would be performed by a board-certified veterinary ophthalmologist.

Enucleation

Enucleation is the surgical removal of the eye. Unfortunately, this is sometimes the best option for some dogs with painful and blind eyes. Many dogs go on to quickly adjust and live normal and good quality lives with only one eye.

Iris Bombe In Dogs – Conclusion

Iris bombe is a serious condition in dogs that can potentially lead to blindness. If you think your dog is showing any signs of this condition, then it’s important to go to your veterinary clinic immediately.

Waiting around to see if your dog gets better by himself, is extremely risky and your dog could end up losing his sight or his eye! Iris bombe in dogs may require surgical correction or long term medical treatment (or both!).

Regular check-ups with your vet are an important part of the recovery process.

Eye conditions can change quickly, so if you notice any negative changes then it’s important to consult your veterinarian, who may change the treatment or medication. With this condition, the sooner you take your dog to the vet, the better the chance of a full recovery.