What is Chorioretinitis?
Chorioretinitis is an eye condition where the back part of the eye, specifically the choroid and the retina, become inflamed. This is a form of uveitis, which generally refers to an inflammation of the parts of the eye known as the uveal tract, but it can also involve nearby structures such as the retina, the blood vessels in the retina, the vitreous (the clear gel that fills the space between the lens and the retina), the head of the optic nerve, and the sclera (the white part of the eye). The Standardization of Uveitis Nomenclature, a group focused on classifying uveitis, sorts the condition into different categories. These depend on where in the eye the inflammation occurs – anterior (front), intermediate (middle), or posterior (back). It also classifies it based on characteristics like whether the inflammation is granulomatous (formed by immune response) or not, and how it occurs, whether suddenly or slowly, ongoing or recurring. Chorioretinitis falls into the posterior category. The choroid, which lies between the retina and the sclera, provides blood supply to the outer layers of the retina. When these layers become inflamed, it can pose a threat to your vision.
What Causes Chorioretinitis?
Uveitis, a condition involving inflammation in the eye, has many possible causes. Depending on the cause, it can be classified as either infectious or noninfectious. Sometimes, it’s present from birth or develops later in life; it can occur for no apparent reason or may be linked to an injury.
Infectious causes of uveitis include things like:
* Toxoplasmosis, a parasitic infection often contracted from cats
* Various viruses such as cytomegalovirus (CMV), herpes simplex, rubella, lymphocytic choriomeningitis virus, and West Nile virus
* Eye diseases related to HIV
* Tuberculosis
* Toxocara, another type of parasitic infection
* Syphilis
* Bartonella, bacteria often transmitted by ticks and fleas
* Fungal infections, specifically those caused by Candida spp.
* Other types of fungal diseases, such as coccidioidomycosis and histoplasmosis
There can also be noninfectious causes of uveitis. Some are linked to other body-wide conditions:
* Sarcoidosis, a disease that leads to inflammation in various body tissues
* Behcets disease, a disorder causing blood vessel inflammation
Other noninfectious causes are not linked to any body-wide conditions:
* Multifocal choroiditis and panuveitis
* Punctate inner choroidopathy
* Multiple evanescent white dots syndrome
* Unilateral acute idiopathic maculopathy
* Birdshot choroidopathy
* Serpiginous choroidopathy
Uveitis can also be caused by cancers like lymphoma or by disorders related to cancer. Conditions like Sympathetic ophthalmia and Vogt Koyanagi Harada syndrome involve inflammation in the layer of blood vessels in the eye. In some cases, posterior scleritis, a condition characterized by severe eye pain and fluid buildup, can mimic the symptoms of uveitis.
Risk Factors and Frequency for Chorioretinitis
Uveitis, an eye condition, is quite widespread, with various studies suggesting a count of 52 to 341 cases per 100,000 people every year in the US. This condition is linked to a significant percentage of blindness cases in the US, ranging from 2.8% to 10%. The most common cause of a specific type of uveitis (posterior uveitis) globally is Toxoplasma chorioretinitis. This disease is more prevalent in tropical nations with hot, humid climates. In the US, it accounts for a quarter of posterior uveitis cases.
In the US, nearly 20% of people carry antibodies to Toxoplasma, an organism that primarily affects people with AIDS. As people age, the occurrence of uveitis increases. This condition results in around 30,000 new cases of legal blindness every year in the US, contributing to 10% to 15% of all instances of total blindness in the nation. Women, particularly during their childbearing years, are more likely to be affected by eye inflammatory conditions than men.
- Uveitis occurs between 52 to 341 per 100,000 people in the US every year.
- The condition contributes to 2.8% to 10% of blindness cases in the United States.
- Toxoplasma chorioretinitis, mostly found in tropical regions, is the leading cause of posterior uveitis.
- In the US, Toxoplasma chorioretinitis accounts for 25% of posterior uveitis cases.
- Nearly 20% of US residents possess antibodies to Toxoplasma, posing a significant threat to individuals with AIDS.
- The likelihood of developing uveitis increases with age.
- Each year, uveitis causes around 30,000 new cases of legal blindness.
- The condition contributes to 10-15% of total blindness cases in the US.
- Women, especially of childbearing age, are more likely to experience eye inflammatory disorders than men.
Signs and Symptoms of Chorioretinitis
People with this condition often experience symptoms such as suddenly seeing floaters or blurred vision, losing their vision or seeing distortions. There might also be a mark in their vision, known as a scotoma, or inflammation causing pain and redness. When these issues happen far from the center of the eye, people might not even notice them. In some cases, they might also see symptoms throughout their body.
When children are born with this condition, known as congenital toxoplasmosis, they may be born early or incredibly small. They might also have symptoms including yellow skin or eyes (jaundice), an enlarged liver or spleen, a rash, eye lesions, an abnormal buildup of cerebrospinal fluid in the brain (hydrocephalus), abnormal deposits in the brain, a smaller head, seizures, or a low vision. Other symptoms in children might include rapidly moving eyes (nystagmus), misaligned eyes (strabismus), or a white pupil reflex (leukocoria). Sometimes, these infections can be linked to having pets.
- Sudden onset of floaters
- Blurred vision
- Loss of vision
- A scotoma (vision mark)
- Distorted vision
- Pain and redness (with inflammation)
- No symptoms (when the issue is in the peripheral vision)
- Body-wide symptoms
- Various symptoms in children (with congenital toxoplasmosis)
- Possible link to having pets
The infections can be identified visually as they have characteristic features. Retinitis often shows up as a white patch with fuzzy borders, whereas inflammation of the choroid (choroiditis) is displayed as yellow patches with regular borders. Over time, these lesions become more sharply defined and may cause pigmentation. However, in many cases, both the retina and choroid are inflamed, which results in chorioretinitis.
Testing for Chorioretinitis
Treating uveitis, an inflammation of the eye’s middle layer, often involves looking at a patient’s overall health, as it can be linked to various other health conditions. To diagnose uveitis, doctors use procedures called direct and indirect ophthalmoscopy to examine the back of the eye. Diagnosis also takes the overall manifestations of the condition into account, which then helps plan a personalized approach for tests based on patients’ individual symptoms and medical history.
In addition, there are more advanced methods to aid in the diagnosis, like fundus fluorescein angiography (FFA), indocyanine green angiography (ICG), B scan ultrasonography, optical coherence tomography (OCT), and fundus autofluorescence.
FFA helps doctors capture images of the back of the eye for diagnosis, keeping track of the disease, and identifying if a lesion is active or inactive. ICG adds on to FFA’s information, focusing on conditions in another layer of the eye, the choroid, which FFA might miss.
OCT uses near-infrared light to create detailed images of the eye. It helps to identify changes to the macula, a part in the center of the retina. B scan ultrasonography is used to get images of the back of your eye when a clear view is hard to get, maybe due to small pupil size or cloudiness in the front of the eye.
Evaluating a patient for uveitis often involves ruling out other health conditions, like syphilis and sarcoidosis. Lab tests, like analyzing eye fluid for certain DNA and measuring levels of antibodies in the blood, are helpful in identifying if the uveitis is due to an infection or not. These tests also help to determine if the infection is new or chronic. For tracking infections in newborns, different types of antibodies are measured, as the mother may pass some antibodies to the baby.
Treatment Options for Chorioretinitis
The aim of treatment for posterior uveitis, an inflammation at the back part of the eye, is to maintain vision. This is achieved by getting rid of any existing infection and reducing the inflammation in the eyes. If an infection is present, antibiotics or antiviral medications are given in combination with drugs that reduce inflammation. These anti-inflammatory drugs are usually started 2 to 3 days after beginning the antimicrobial treatment. For inflammation without infection, the primary treatment is steroids and medications to suppress the immune system. These can be given in a variety of ways, such as eye drops, injections around or into the eye, or pills taken orally. It’s also crucial to treat any underlying health conditions that may be causing the inflammation.
In cases of ocular toxoplasmosis, an eye infection caused by a parasite, the treatment involves antiparasitic drugs combined with systemic corticosteroids, a type of anti-inflammatory drug. The antiparasitic medication Pyrimethamine is usually given with a loading dose for 1-2 days, then taken daily for about a month. It’s given with folinic acid to prevent a deficiency in folate, an essential nutrient. Sulfadiazine is usually taken in combination with Pyrimethamine for about a month. The corticosteroids are typically started 3 days after starting the antimicrobial therapy. If the patient is allergic to sulfonamides, potential replacements include clindamycin or azithromycin. Another combination could be Sulfamethoxazole-trimethoprim. Atovaquone is also an option and is taken for 4 to 6 weeks. For pregnant patients, Spiramycin is the safest antiparasitic drug.
If the uveitis is not caused by an infection, treatment mainly involves systemic steroids like oral Prednisolone. If the uveitis threatens vision, especially if it affects the optic nerve head or the macular/foveal (central) areas of the retina, intravenous methylprednisolone may be given for 3 days, followed by decreasing doses of oral Prednisolone.
In cases where steroids don’t help or can’t be used due to long-term side effects, immunomodulatory agents can be useful. These include cyclosporine, azathioprine, mycophenolate mofetil, and methotrexate. Biological immunomodulators, such as adalimumab or infliximab could be considered when first-line therapies do not work.
In case of complications like choroidal neovascular membrane, treatments may include anti-VEGF agents (like bevacizumab or ranibizumab), corticosteroids, or photodynamic therapy. Surgical treatments, including vitrectomy (surgery to remove the vitreous gel from the eye), cryotherapy, or laser photocoagulation could be necessary for handling these complications.
What else can Chorioretinitis be?
There are a variety of health conditions that can cause posterior uveitis, an inflammation of the back of the eye, that sometimes can look a lot like one another. For example, sometimes eye issues related to aging, multiple central serous retinopathy (a condition where fluid builds up under the retina), posterior scleritis (inflammation of the wall of the eye), and eye cancers can appear similar to posterior uveitis. Certain infections that cause inflammation and damage to the retina and choroid (layers at the back of the eye) can look significantly different from conditions characterized by white dots on the retina, and tests such as Indocyanine Green Angiography (ICGA) and Fluorescein Angiography (FFA) can usually help identify them reliably.
In newborn babies who have an infection from birth, it’s essential to rule out diseases included in TORCHeS, a group of infections that can lead to serious illnesses. Less common infections that look like toxoplasmosis (a disease caused by a parasite) include West Nile virus, acute lymphocytic choriomeningitis (a viral infection that can affect the brain and meninges), and the Zika virus, particularly when the baby has a smaller than normal head size. Tumors such as retinoblastoma (a rare form of eye cancer) and congenital anomalies (birth defects) of the retina or choroid, like retinochoroidal coloboma (a hole in one of the structures of the eye) and persistent hyperplastic vitreous (a condition where the eye maintains its fetal structure), are also things doctors would consider when diagnosing eye conditions in children.
What to expect with Chorioretinitis
The chances of regaining vision after a chorioretinal lesion depend on several factors. These include the location of the lesion, any subsequent recurrences, and any other issues related to the back part of the eye. Lesions that are near the macula and optic nerve can result in severe vision loss (20/200 or worse).
Toxoplasma, a type of infection, tends to reoccur after an active episode. However, the outlook is good for individuals with a healthy immune system, especially if the central part of the macula is unaffected.
Possible Complications When Diagnosed with Chorioretinitis
Uveitis, an inflammation of the middle layer of the eye, can lead to vision loss or even blindness. This can occur due to several reasons, including secondary complications such as:
- Cataract, a clouding of the eye lens
- Secondary glaucoma, an increase in eye pressure
- Choroidal neovascularization, new blood vessels growing under the retina
- Cystoid macular edema, a buildup of fluid in the eye causing blurred vision
- Optic neuropathy, damage to the optic nerve
- Retinal detachment, where the retina pulls away from the back of the eye
- Retinal vascular occlusion, blockage of the blood vessels in the retina
- Hemorrhage, or bleeding in the eye
- Phthisis, or shrinkage of the eye.
In the case of noninfectious posterior uveitis, the most frequent complication is Cystoid macular edema (CME). This is particularly common in conditions like birdshot chorioretinitis, sarcoidosis, and other types of uveitis that cause extensive inflammation inside the eye. Another complication, Choroidal neovascularization (CNV), is more likely to occur when the choroid layer of the eye is involved and the Bruch’s membrane is disrupted. Some conditions that can cause CNV include presumed ocular histoplasmosis syndrome, multifocal choroiditis and panuveitis, serpiginous choroiditis, and punctate inner choroidopathy.
Preventing Chorioretinitis
To prevent infection from Toxoplasmosis – a common disease that can affect anyone, especially pregnant women and people with HIV – it is advised that certain measures be taken. For starters, avoiding the consumption of raw or undercooked meat is necessary. Also, seafood like raw oysters, clams, or mussels can carry this infection, so they should be avoided.
Moreover, the Toxoplasmosis parasite can be eliminated by heating food at 60 degrees Celsius for 15 minutes or by freezing it at -20 degrees Celsius for 24 hours. So, ensure all your meals are thoroughly cooked or frozen properly. It is also recommended to only consume water that has been either well-filtered or boiled.
Since the disease can be spread through cats and their droppings in soil or litter boxes, try and stay away from them. If cat contact is unavoidable, you should wear gloves when possible and wash your hands after touching soil or litter boxes. Plus, remember to peel fruits and wash fruits and vegetables thoroughly before eating them.
Women who get infected with Toxoplasmosis during their pregnancy especially need to understand the risks it poses not just to them but to their unborn child. They are advised to seek expert advice on this matter.