Posterior uveitis is a rare type of uveitis. If it is not handled or treated properly and on time, there could be loss of vision. Posterior uveitis can affect people of any age including children and it affects either one eye or both eyes. The eye is one of the most delicate part of the body, any disorder can lead to partial or full blindness. So, any disease, trauma or inflammation that affects the eyes can cause serious complications. Continue reading this article to know all about posterior uveitis, its causes , symptoms and treatment methods.
WHAT IS POSTERIOR UVEITIS?
The uvea is part of the eye with a thick and strong fibrous tissues that surround and protect the eye. It is made up of many blood vessels and tissues. The uvea has three parts which are the iris, the cillary body and the choroid. The iris is the thin, circular and coloured structure of the eye that allows light to enter into the light, it also control the size of the pupil.
The cillary body is responsible for making the fluid that fills the eye while the choroid is the middle layer of the eye that contains vessels and connective tissues. When an inflammation affect any of these structures, then it is known as uveitis. It can affect one or two structures of the uvea.
There are four types of uveitis which are:
- Anterior Uveitis: This is an inflammation that affects the front part of the eye which is the iris. This is the most common type of uveitis that occur in about 80% of cases.
- Intermediate Uveitis: Also known as pars planitis or cyclitis, this is an inflammation that affects the tissues just behind lens and iris.
- Posterior Uveitis or Choroiditis: This is an inflammation of the choroid, it can also affect the optic nerve and can lead to loss of vision.
- Panuveitis: This is an inflammation of the whole eye, it can affect any part. There is no specific area this inflammation is limited to.
Posterior uveitis is very rare but has serious complications. It is common in people who have weak immune system or those with certain genes. However, people with normal and strong immune system can have posterior uveitis.
CAUSES OF POSTERIOR UVEITIS
Uveitis can be caused by factors such as:
- Injury or trauma to the eye
- Toxic material or foreign objects
- Weak immune system
- Infections
Sometimes, inflammation can destroy tissues behind the eyes. There are many causes of posterior uveitis.
Some are caused by:
- Viral infections like herpes simplex virus, herpes zoster virus, cytomegalovirus, measles, rubella, West Nile virus, dengue and chikungunya virus.
- Bacterial infections like syphilis, tuberculosis, endogenous endophthalmitis,
- Parasitic infections like toxoplasmosis,
- Allergies
- Injury or trauma to the eye
- Autoimmune disorders that causes the immune system to fight against itself
- Systematic disorders such as Behcet’s syndrome, ankylosing spondylitis, Lyme disease, sarcoidosis and psoriasis.
Also, there are some factors that can increase the risk of developing posterior uveitis.
- These factors are:
- Weak immune system
- Having a certain gene like HLA-A29
- Having contact with or exposing yourself to contaminated water, animals and raw meat.
SYMPTOMS OF POSTERIOR UVEITIS
Some symptoms of posterior uveitis are:
- Blurry vision
- Difficulty in seeing colours
- Difficulty in seeing in the dark or at night
- Sensitivity to light
- Reduction in the sharpness of vision
- Feeling of small specks in the eye that block vision
- Watering of the eye
- Redness in the eye
- Loss of vision in severe cases.
HOW TO DIAGNOSE POSTERIOR UVEITIS
To diagnose posterior uveitis, the doctor can ask about medical history to know if the inflammation is caused by any underlying disease. Tests are also carried out to know if the symptoms are caused by either infectious or immune conditions, this will help you to the treatment method to use. Blood tests are very important to check for viral, bacterial or parasitic agents. Cheat tests or respiratory examinations are conducted to check for tuberculosis or sarcoidosis. An ophthalmic exam that shows the vitreous humor is also conducted to clearly show the inflammation and structure of the eye. Other eye exams include:
- Ocular Pressure: This is done to measure the pressure of fluid in the eye. It is very important when evaluating eye diseases like uveitis and glaucoma.
- Eye Chart Or Visual Acuity Test: To check how well you see objects, symbols and letters, this test is conducted. It is done using a chart of symbols or letters.
- Slit Lamp Examination: Your doctor uses a bright light to check the insides of the eye for injuries and diseases. It helps the ophthalmologist to get a closer and clearer view of the inside of the eyes and around them as well.
- Scleral Depression: This is a technique that involves using an equipment on as scleral depressor to examine the peripheral retina. You can view the peripheral retina, oral serrata, and pars plana at different angles.
- Fundoscopic Examination: This is the use of ophthalmoscope to see the insides ( fundus) of the eye and other structure. This instrument has small lenses attached to it that allow the doctor to easily examine the eye.
- Imaging: The interior part of the eyes are viewed and a visual representation is made as well. This test can be done using technologies like x-rays, CT scan, mammography and nuclear medicine.
- Intraocular Fluid Evaluation For Polymerase Testing: This exam is conducted to diagnose any infective disease that affects the eye. It is mostly used to detect microorganisms that may have caused diseases like uveitis.
- Optical Coherence Tomography (OCT) Imaging: This exam is done to check for the back of the eye. This test uses reflected light to measure how thick the choroid and retina and if there is inflammation in them.
Your doctor will classify your posterior uveitis based on:
- The number of times it occurs and for how long it lasted
- One eye or both eyes
- Caused by infections or non infections
- Location of the inflammation
- If it has glaucoma
TREATMENTS FOR POSTERIOR UVEITIS
The cause of the eye inflammation will determine the treatment options.
Posterior uveitis can be treated using the following:
1. Corticosteroids
These are used to reduce the activity of the immune system and also reduce how white blood cells and inflammation-causing chemicals are moved to the area of inflammation. They can reduce symptoms like redness of the eye, itching and pain. However, they should not be used on a long term base to avoid complications like infections.
Corticosteroids can be injected directly into the eye, intravitreal (administering the drug into the vitreous humor of the eye), oral or intravenously. You should stick to the prescribed dose and stop taking the drug when required.
2. Immunomodulatory Therapy
This treatment is aimed towards suppressing the immune system and helping the body to fight against infection, and diseases. This is used when the patient is not responding to systematic corticosteroids but needs to continue getting treatment. Some of these drugs for posterior uveitis are Voclosporin, Cyclosporin A, Tacrolimus, Azathioprine, Mycophenolate mofetil, Cyclophosphamide and Chlorambucil.
3. Ocular Gene Therapy
This is a treatment method that can be used to treat eye diseases. It involves injecting small amounts of adeno-associated virus (AAV) and lentivirus. These viruses are like vectors, they carry or help organisms to aubsatmces from place to place. These vectors have anti-inflammatory properties that can treat posterior uveitis.
4. Biologic Response Modifiers (BRM)
These are molecules or xompunds that restrain the activities of the immune system response. They mark or shoot at specific proteins, analogues, cytokines, and interleukins.
5. Medication-Releasing Implant
This is used when other treatment methods do not cure uveitis. It involves implanting a device in the eye, this device releases corticosteroids slowly into the years for two to three years.
It is very important to detect the cause of posterior uveitis and treat it as well as the eye inflammation. Infection should be treated first before any anti-inflammatory therapy or treatment. It is also recommended that patients undergo screening for additional diseases or condition that may prevent the use of certain drugs like examining the liver, haematological status and how well the kidneys work.
CONCLUSION
Posterior uveitis is an inflammation that affects the choroid. The choroid contains vessels and connective tissues, it is the middle layer of the eye. This inflammation can be caused by many factors like infections, injury and trauma, allergies, autoimmune condition and systematic diseases.
Some symptoms of this eye inflammation are blurry vision, sensitivity to light, difficulty in seeing colours or seeing at night, redness of the eyes, pain and itching. To treat this inflammation, the cause of the disease should be treated first. It is very important that you treat posterior uveitis immediately the symptoms show to avoid cataract, glaucoma or loss of vision.