Understanding ICAA and Its impact
Here’s how it works: The front part of the eye has two important parts called the iris and the cornea. The iris is the colored part of the eye, like the blue or brown part, and the cornea is the transparent, curved surface that covers the front of the eye. Where these two parts meet, there’s a tiny area that drains a fluid called aqueous humor. Aqueous humor is a transparent fluid produced in the eye that maintains eye pressure and provides nutrients to the eye. This fluid is crucial because it keeps the pressure in the eye at a healthy level.
It’s like a water balloon inflating too much
In severe cases of ICAA, this drainage area can malfunction significantly, causing the fluid to build up and leading to high pressure in the eye. It’s like a water balloon inflating too much. Consequently, this pressure damages the retina, the light-sensitive layer at the back of the eye that captures what your dog sees, and the optic nerve, the cable that carries those images to the brain. This high pressure is known as primary acute glaucoma. If not diagnosed and treated preventively, severe ICAA can cause irreversible blindness.
How Carlotta’s light went out
This happened with Carlotta. Shortly after her normal eye exam (without gonioscopy), which showed “eyes-clear” and a normal eye pressure of 15mmHg, something went terribly wrong. One night, Carlotta became restless and didn’t know where to lie down. Chiara tried to comfort her and noticed that Carlotta’s left blue eye had lost its brightness. The pupil was dilated compared to the other eye, and the white part had turned red. Carlotta also had her third eyelid, a protective membrane in the inner corner of the eye, showing in both eyes due to pain. As a vet since 1997, Chiara immediately recognized this as glaucoma. She phoned the ophthalmologist, who examined Carlotta right away. Unfortunately, they were already too late: her left eye pressure was extremely high (50 mmHg), and it was damaged within a very short time, becoming blind.
Determining the type of glaucoma
The day after that horrible night, Chiara wanted to determine if Carlotta had primary or secondary glaucoma. Secondary glaucoma can develop from other eye issues such as inflammation, cataracts (clouding of the lens), lens luxation (displacement of the lens), trauma, or tumors. It has a better prognosis because it typically affects only one eye. In contrast, primary glaucoma, which is more common in our breed and directly linked to Iridocorneal Angle Abnormality (ICAA), affects both eyes. In Severe-ICAA dogs, primary acute glaucoma almost always occurs during the night because pupillary dilation can cause complete closure of the iridocorneal angle, leading to a significant increase in eye pressure.
Carlotta’s eye after the acute glaucom
Using UBM for a detailed examination
Although they diagnosed severe ICAA with gonioscopy, Chiara and the ophthalmologist chose UBM to ensure that glaucoma was not developing in Carlotta’s right eye also. While both eyes have ICAA, glaucoma affects one eye first. The other eye has a significant risk of developing glaucoma within 6-12 months. Using preventive medication (eye drops) in the “healthy eye” can delay the onset of glaucoma in the second eye. It was important to know if Carlotta’s right eye could be saved.
Revealing crucial insights with UBM
UBM provides a more detailed view than gonioscopy, and it was important for a thorough examination. It uses high-frequency sound waves to create detailed images of the eye’s interior. It shows the front part of the eye, including the cornea (the transparent, curved surface), the iris (the colored part), the ciliary body (a part that helps the eye focus and produces the aqueous humor), and the drainage angle (where eye fluid flows out). This technique helps identify problems in these areas, such as ICAA, glaucoma, tumors, and other abnormalities. The UBM results showed that Carlotta’s right eye was not developing glaucoma yet, and preventive treatment was needed to postpone it. Eye drops are not effective in lowering the pressure in the eye with primary glaucoma, but they are effective in delaying the appearance of glaucoma in eyes severely affected by ICAA.
Early Detection: The key to preventing vision loss
Glaucoma has symptoms like redness, pain, a cloudy appearance in the eye, and sudden vision loss, as seen with Carlotta. In contrast, ICAA itself has no symptoms. Severe cases of ICAA are like a Trojan horse, predisposing the eye to build up pressure without showing any signs to the dog’s owner. Carlotta even had two regular eye exams without detecting the defect because her eye pressure was at the normal level of 15 mmHg.
ICAA is like a Trojan horse, building up eye pressure without showing any signs to the dog’s owner.
The key to preventing vision loss lies in early detection of ICAA. This is where a specialized exam called gonioscopy comes in. During this painless procedure, your ophthalmologist uses a special contact lens to directly visualize the drainage area at the front of the eye (iridocorneal angle). This allows for early identification of ICAA, crucial for preventing the development of glaucoma.
A regular eye exam done by an ophthalmologist typically does not include gonioscopy. Since ICAA often appears later in life, schedule your dog’s first gonioscopy at 1 year old. If the initial gonioscopy shows the dog is ICAA-unaffected, follow up with checkups every 3 years (at ages 1, 4, and 7). ICAA-affected dogs may require closer checks, on the advice of the ophthalmologist, to see if their condition worsens.
Understanding your dog’s ICAA Severity
When your ophthalmologist performs a gonioscopy, they will look for several key things:
Angle Width: This can be normal, narrow, or closed. A normal angle allows for proper drainage of eye fluid, while narrow or closed angles can cause drainage problems, increasing the risk of glaucoma.
Pectinate Ligament: The pectinate ligament is like a tea strainer; if the holes are too small, they can easily become blocked, leading to acute glaucoma. This tiny structure helps drain fluid from the eye. The vet will check its shape and how the fibers are spaced. If the fibers are too large or too close together, they can block drainage.
The assessment of the angle width, along with the condition of the pectinate ligament, helps determine the grade of ICAA (mild, moderate, or severe).
Explaining ICAA grading schemes
Understanding your dog’s ICAA severity is important for their health now and in the future. Most grading schemes classify ICAA as mild, moderate, or severe. Here’s what each grade means and what you should do.
Mild ICAA (Grade 3)
- Normal (open) angle with minor abnormalities in the pectinate ligament
- Low risk of glaucoma
- Next checkup on the advice of the ophthalmologist to verify if the condition progresses to moderate or severe ICAA
- Breeding only with an ICAA-free (unaffected) partner
Moderate ICAA (Grade 2)
- Open or narrow angle with more significant abnormalities in the pectinate ligament
- Medium risk of glaucoma
- Next checkup on the advice of the ophthalmologist to verify if the condition progresses to severe ICAA
- Breeding only with an ICAA-free (unaffected) partner and advise to test offspring for ICAA
Severe ICAA (Grade 1)
- Narrow or closed angle with severe abnormalities in the pectinate ligament
- High risk of glaucoma
- Regular eye-pressure check to ensure that’s always below 20 mmHg and need for preventive medical therapy
- No breeding
Searching for the mutation
ICAA is not part of the multi-ocular eye defect. Its unknown if its inherited in a straightforward way, like those that need two copies of the same gene (homozygous) or just one copy (heterozygous). An ICAA-affected dog can be MOD-free. It’s also unclear if it is inherited in the same way as cataracts, which are suspected to be autosomal recessive and require two copies of the defective gene to show the disease.
Cambridge researchers are in need of more DNA-samples but collecting them from affected dogs is proving to be a challenge.
Let’s face it, it would be a breeder’s dream to have a DNA test for ICAA. The good news is that researchers at the University of Cambridge are eager to work on this. They are focused on developing a breed-specific DNA test, similar to their success with Border Collies. However, to find the mutation, they need more DNA samples, especially from dogs older than 4 years. At this age, if they are affected, their ICAA grade won’t change anymore. Collecting these samples is proving to be a challenge.
Luckily, one country in Europe, the Czech Republic, has been conducting gonioscopy for years. That’s remarkable because many countries in Europe still don’t require regular eye exams. Carlotta lost her sight in September 2022, and since then, Chiara has made it her mission to bring this issue to the attention of breeders. This effort paid off when a breeder from the Czech Republic remembered her veterinarian mentioning ICAA during an eye exam in 2018.
Raising awareness
Since Carlotta developed glaucoma, awareness of ICAA has been growing very slowly. Only a handful of people outside countries like the Czech Republic, Slovakia, and Poland perform gonioscopy. There are not many cases of primary glaucoma registered by ECVO (European College of Veterinary Ophthalmologists) and ACVO (American College of Veterinary Ophthalmologists).
Even for Chiara, it took some time and persuasion to get Carlotta’s result certified by ECVO. The ophthalmologist said, “I’ll prepare it for you next week.” But it ended with, “What do you need the ECVO certificate for if she’s now blind? You can’t breed her, so there’s no point in recording it with the ECVO.” In January 2023, Chiara finally received the certificate with Carlotta’s glaucoma noted.
Mandatory gonioscopy for ECVO Certification
Chiara’s dedicated efforts to raise awareness about ICAA have been recognized by the ECVO. From June 2024, our breed is on the list requiring ophthalmologists to perform gonioscopy during regular eye exams for ECVO certification. This change isn’t solely because of Carlotta, but because our breed has been at risk for affected dogs for years.
Many people still think that there are no blind dogs in our breed
Many people still think that there are no blind dogs in our breed, but Chiara decided to have Carlotta’s eyes tested after reading a story on Facebook. This post was about a dog who had to have both its eyes enucleated, which means surgically removed, for reasons that were not published. This dog was a relative of Carlotta, and Chiara was worried because of this connection. The vet in her urged her to test her own pet too. Cases like these were posted in Facebook groups from time to time, with owners hardly realizing why their dogs became blind.
Managing Carlotta’s sight
It’s always difficult when a new disease is found in our breed. But with a simple test, it’s easy to prevent cases like Carlotta. Primary glaucoma is a chronic disease with no cure, but effective management can significantly improve your dog’s quality of life. The key goals are controlling intraocular pressure (IOP) to prevent optic nerve damage and vision loss, managing pain, and preserving remaining vision whenever possible.
Chiara handling the tonovet to control Carlotta’s eye pressure
Chiara has been managing Carlotta’s sight for almost 2 years now. It’s a true battle, and thanks to her experience as a vet, she has the tools to help her girl live a comfortable life. Carlotta is fortunate to have Chiara as her owner because most pet owners would find it challenging to handle a Tonovet and provide the same level of care. A Tonovet is an instrument commonly used to measure eye pressure, and Chiara has been trained to use it at home. She monitors Carlotta’s eye pressure every day, both morning and evening. Additionally, she administers preventive eye drops twice a day in the right eye to ensure the intraocular pressure always remains below 20 mmHg.
Race against high eye pressure
If the intraocular pressure rises above 20-25 mmHg, Carlotta will need to be taken as quickly as possible to an ophthalmologist specialized in applying a gonioimplant. This small tube, placed inside the eye, has a valve that opens when the intraocular pressure increases, helping to save the eye for approximately one year.
The challenge is that the nearest ophthalmologist who can perform this surgery is 500 km away from where Carlotta lives. It will be a race against time, as an eye pressure of 50 mmHg can cause permanent blindness within 6 hours as happened with her left eye.
From a Facebook post to action
Pictures of Carlotta’s eyes were widely shared on social media. The goal was not to blame breeders but to educate people in our breed that we can prevent glaucoma with simple testing and smart breeding decisions. Chiara reached out to an Italian breeder who contacted her for help with testing. They drove together to test the breeder’s dogs. The drive proved worthwhile.
Thanks to Chiara’s ongoing efforts to raise awareness about ICAA and glaucoma, at least one dog’s vision has been saved. The breeder immediately started preventive glaucoma treatment to keep his eye pressure under control and to prevent glaucoma. These eye drops work by reducing the production of aqueous humor, the fluid in the eye, which is produced by a part of the eye called the ciliary body. In severe ICAA cases, eye drops are used preventively even when the eye pressure (intraocular pressure, IOP) is normal. It’s crucial to keep the IOP as low as possible, even within the normal range, to prevent glaucoma from developing. In ICAA-severe cases, the eye pressure usually remains normal (below 20 mmHg) until glaucoma appears and causes an increase. Once primary glaucoma develops, no eye drops can reduce the IOP anymore.
Don’t talk, just test
Chiara’s life is deeply affected by Carlotta’s condition. People who think a blind dog can have a happy and good life may not fully understand what glaucoma entails. Glaucoma can be very painful due to increased pressure inside the eye. Additionally, it’s challenging to prevent glaucoma from affecting her “good” eye.
People who think a blind dog can have a happy and good life may not fully understand what glaucoma entails
It’s a constant challenge to keep the pressure in her blind eye below 40 mmHg to prevent pain. Many people ask why she doesn’t remove Carlotta’s blind eye. However, the surgery requires general anesthesia, and some of the drugs used can cause pupil dilation. This dilation could increase eye pressure in ICAA-severe dogs, potentially triggering acute primary glaucoma in her “good” eye. Therefore, owners of ICAA-affected dogs need to be especially cautious.
Chiara’s battle to save Carlotta’s vision
Chiara dedicates her life to preserving Carlotta’s sight. By measuring the eye pressure in both eyes with a Tonovet, she discovered that taking Carlotta to the mountains at altitudes above 1600 meters keeps the pressure in her left eye with glaucoma below 40 mmHg. To maintain this benefit, Carlotta spends at least 2-3 days a week in the high mountains. On the other days, Chiara treats her with lymphatic drainage massages of the head and neck twice a day. Unfortunately, the beneficial effect is diminishing, and the ophthalmologist has warned Chiara that primary glaucoma always wins. Carlotta’s left eye will likely need to be enucleated soon to control the pain. Carlotta is only 6 years old, but her battle against glaucoma has already lasted nearly 2 years.
While there are more severe issues in our breed, such as autoimmune diseases and lymphoma, glaucoma is currently preventable through testing. By testing all breeding dogs and not breeding severely affected dogs, we can prevent this painful condition. We managed this before with DNA testing for EIC, PCD, and CA. So let’s use gonioscopy as a tool to prevent ICAA and glaucoma!