What is Birdshot Retinopathy?
Birdshot chorioretinopathy (BCR) is a type of eye disease that affects both eyes and lasts for a long time. It is connected with a certain variant of a gene (HLA-A29) that our bodies use to maintain immunity. This disease often affects people in middle age, and women are more likely to get it than men. Early on, the symptoms can be mild, which might delay treatment and eventually cause permanent changes to vision.
BCR is enduring, long-term, and worsens overtime. As a result, it can cause permanent harm to the eyes.
The term “Birdshot chorioretinopathy” was first used in 1980. Before that, the illness was reported in 1949 as “candle wax spot chorioretinopathy” when there were small white color changes within the eye. Its characteristic signs include a white, painless eye with little inflammation but deep-seated cream-colored spots, leakage from the blood vessels in the retina (the layer of tissue at the back of the inner eye that processes visual information and sends it to the brain), and vitritis (an inflammation inside the eye).
Since this disease was defined and described further, doctors have made advances in its treatment and patient outcomes have improved significantly. One of the major breakthroughs was understanding how the disease triggers the immune system.
What Causes Birdshot Retinopathy?
The exact cause of this condition is still a mystery, but it’s believed to be connected to an autoimmune disease. An autoimmune disease is a condition in which your immune system mistakenly attacks your body. This connection is suspected because a certain genetic marker, called HLA-A29, has been found in a very large proportion of cases. However, it’s still not clear what triggers this autoimmune response.
Risk Factors and Frequency for Birdshot Retinopathy
Birdshot chorioretinopathy is a rare form of eye inflammation. Because it’s not very common, it’s hard to get reliable numbers on how many people have it. That said, studies from both Europe and the United States estimate that it makes up between 0.5% and 1.5% of the cases of uveitis – another type of eye inflammation – seen by specialists. Though it can occur in anyone, it’s most often seen in middle-aged people and appears to be slightly more common in females.
- Birdshot chorioretinopathy is a rare cause of eye inflammation.
- It represents 0.5% to 1.5% of uveitis cases seen by specialists.
- It’s more commonly seen in middle-aged people.
- It appears to be slightly more common in females.
- The average age of onset is around 53 years old.
- 54.1% of patients are female.
Moreover, Birdshot chorioretinopathy is most commonly found in White populations, especially those of Northern European ancestry. There are only rare instances of the disease among Latino-Hispanic, African-American, and Japanese individuals. The distribution among ethnicities is somehow linked to the HLA-A29 gene, with different subtypes of the gene observed among patients having different rates of prevalence.
Signs and Symptoms of Birdshot Retinopathy
Birdshot eye disease comes with symptoms that develop over time. You may initially notice things like floating spots in your vision, blurry vision, and a general decrease in your sight. As the disease progresses, patients often experience additional symptoms, which can include difficulty seeing in low light, problems with distinguishing between different levels of light and dark, and trouble distinguishing colors.
Doctors can often diagnose this disease through an examination of the back of your eye (fundus examination). This can show signs of inflammation and numerous tiny yellow-white spots beneath the optic nerve – the part of your eye that sends visual information to the brain. These spots are usually 500 to 1500 micrometers across. The way these spots appear and spread in the eye is what gives the disease its name, ‘birdshot’. Over time, these spots can merge and form linear patterns around the veins in your eyes, giving a more worn-out appearance.
Testing for Birdshot Retinopathy
If you’re suspected of having Birdshot Chorioretinopathy (BCR), fluorecein angiography, which is a diagnostic procedure to look at the blood vessels and flow of blood through the retina and choroid, might show leakage from the blood vessels in the retina and the optic nerve head, which is the part where the optic nerve exits the back of the eye. The leakage could cause a swelling in the macula (the area of the retina responsible for sharp central vision) and is often believed to be the main cause of vision loss in patients with BCR.
To confirm if you have BCR, your doctor could carry out tests that include HLA-A29 and syphilis serology, along with examining the amount of angiotensin-converting enzyme (ACE) in your blood. They might also run an interferon-gamma release assay or a Mantoux test if you’re at high risk. Further investigations could include a chest x-ray to look for signs of conditions such as sarcoidosis or tuberculosis, as well as procedures like Indocyanine green angiography, fluorescein angiography, and electroretinography – these are all imaging techniques to carefully examine various aspects of the eye.
In order to be diagnosed with BCR, certain conditions need to be met. These include having the condition in both eyes; having more than three distinct birdshot lesions – these are creamy-colored, irregular spots on the retina that can be seen during an eye examination – located inferior or nasal to the optic disk in one eye; having minimal inflammation in the anterior chamber of the eye; and no more than a moderate level of inflammation in the vitreous, which is the clear gel that fills the space between the lens and the retina of the eye.
Treatment Options for Birdshot Retinopathy
Treatment for this eye condition often employs steroids and therapies that control the immune system. Steroids can either be swallowed or placed directly into the eye through an injection or small device. There is a growing trend of using steroids inside the eye to control the progression of the disease. However, steroids can cause a rise in eye pressure, and if not monitored, it can lead to permanent vision loss. That’s why, when on steroids, it’s essential to regularly check your eye pressure. This issue may not show any symptoms until vision loss has taken place.
Many of the immune-modulating therapies currently in use can have intense side effects. It’s important to discuss these potential side effects in detail with your doctor before starting these therapies. Unfortunately, there isn’t a one-size-fits-all treatment plan that works for everyone. Sometimes, multiple combinations may be necessary to control the eye inflammation. The ultimate goal is to find the smallest amount of medication that successfully controls the inflammation in your eye.
It’s common for a patient to consult with a rheumatologist (a specialist in treating diseases of the joints, muscles, and ligaments) or a nephrologist (a kidney specialist) for testing and management of these immune-modulating therapies. With the use of these therapies, vision quality can remain stable or even improve significantly.
What else can Birdshot Retinopathy be?
There are various conditions that can cause eye problems, which are generally categorized as infectious or non-infectious. Below are some examples of these conditions:
- Infectious:
- Tuberculosis
- Syphilis
- Ocular histoplasmosis syndrome
- Non-Infectious:
- Sarcoidosis
- Vogt-Koyanagi-Harada syndrome
- Sympathetic ophthalmia
- Acute posterior multifocal placoid pigment epitheliopathy (APMPPE)
- Multiple evanescent white dot syndrome (MEWDS)
- Multifocal choroiditis and panuveitis (MCP)
- Punctate inner choroidopathy (PIC)
Among these conditions, it’s worth noting that lymphoma, a type of cancer, can disguise itself to appear like birdshot retinopathy, which is an inflammation of the retina.
What to expect with Birdshot Retinopathy
Birdshot chorioretinopathy is a disease that gets worse over time and may severely affect vision because of physical changes and functional problems in the eye.
Possible Complications When Diagnosed with Birdshot Retinopathy
The main reasons for vision loss in Birdshot Chorioretinopathy (BCR) include persistent cystoid macular edema (CME), macular scarring, the development of new blood vessels beneath the retina, and a condition known as cellophane maculopathy. Widespread retinal dysfunction associated with long-term disease is a noted considerable risk factor for vision loss.
Common Causes of Vision Loss in BCR:
- Persistent cystoid macular edema (CME)
- Macular scarring
- Development of new blood vessels beneath the retina
- Cellophane maculopathy
- Widespread retinal dysfunction over a long disease duration
Preventing Birdshot Retinopathy
Birdshot is a type of eye disease that requires regular monitoring by an eye doctor, known as an ophthalmologist. If you notice any sudden changes in your vision or experience symptoms like pain or discomfort, it’s crucial to see an ophthalmologist immediately. Even when your vision seems fine, you might still need to have an eye exam. This is because the exam can detect even a small amount of inflammation, which isn’t always noticeable. It’s important to have an open discussion with your local ophthalmologist about the steps for your treatment and plan for future visits.
