Posterior Uveitis: Protecting Your Vision From Inflammation
Understanding Posterior Uveitis
The uvea is the middle layer of the eye. It includes the iris at the front, the ciliary body in the middle, and the choroid at the back. Posterior uveitis refers to inflammation in the back part of the uvea. This mainly involves the choroid and sometimes the retina or optic nerve. The choroid supplies blood and nutrients to the outer layers of the retina, so inflammation here can directly threaten vision.
Posterior uveitis is different from anterior uveitis, which affects the front of the eye. Anterior uveitis typically causes more noticeable redness and pain. Because the retina and choroid lack pain-sensing nerves, posterior uveitis may develop with few obvious symptoms at first.
Posterior uveitis can be divided into two broad categories: infectious and non-infectious. Infectious posterior uveitis is caused by organisms such as parasites, bacteria, or viruses. Non-infectious posterior uveitis results from the body's own immune system attacking eye tissues. In the developed world, non-infectious forms are generally more common. However, infections remain a leading cause worldwide.
In non-infectious choroiditis, there are at least two main ways inflammation harms the eye. In the first, inflammatory cells infiltrate the stroma (the supportive tissue of the choroid). In the second, inflammation targets the choriocapillaris (the fine network of blood vessels closest to the retina). This causes areas of poor blood flow. Both mechanisms can damage the Bruch membrane and retinal pigment epithelium complex. Together these structures form the outer blood-retinal barrier. When this barrier breaks down, fluid can leak under the retina. Abnormal new blood vessels called choroidal neovascularization may also develop.
Who Is Affected and Risk Factors
In the United States, the prevalence of noninfectious uveitis in adults is approximately 121 cases per 100,000 persons (Gritz and Wong, Ophthalmology, 2004). Posterior uveitis is the second most common form of uveitis overall. It accounts for roughly 4.7% to 30% of all uveitis cases depending on the study population (Retina Today, 2017). Uncontrolled inflammation from uveitis is estimated to be responsible for about 10% of blindness in the United States.
People with certain autoimmune or systemic inflammatory diseases face a higher risk of developing posterior uveitis. Conditions associated with choroiditis include:
- Sarcoidosis, a disease that causes clusters of inflammatory cells in various organs
- Behcet disease, a condition causing blood vessel inflammation throughout the body
- Vogt-Koyanagi-Harada (VKH) syndrome, an autoimmune disease affecting pigmented tissues including the choroid
- Birdshot chorioretinopathy, a chronic inflammatory condition of the retina and choroid
- Multifocal choroiditis, seen most frequently in women ages 20 to 60
Infections are among the most common causes of posterior uveitis worldwide. Toxoplasmosis, a parasitic infection, is a leading cause. It can produce retinal scarring that may cause lasting vision loss. Other infectious triggers include herpes viruses, cytomegalovirus (CMV), tuberculosis, and syphilis. A thorough evaluation is needed to identify or rule out infectious causes. Treatment differs significantly from treatment for non-infectious forms.
A history of eye infections or prior episodes of uveitis increases the likelihood of recurrence. People with weakened immune systems may be more vulnerable to infectious forms. This applies whether the immune weakness comes from medication or underlying conditions. Posterior uveitis can occur at any age. Certain subtypes are more common in specific age groups and demographic populations.
Signs and Symptoms
The symptoms of posterior uveitis often develop gradually and can affect one or both eyes. Common complaints include:
- Blurry or hazy vision
- Floaters, which appear as spots, strings, or cobwebs drifting across the field of vision
- Blind spots or dark areas in vision
- Sensitivity to light, also called photophobia
Unlike anterior uveitis, posterior uveitis often does not cause significant pain. This is because the retina and choroid lack pain-sensing nerves. Some people may notice mild redness, a dull pressure-like discomfort, or light sensitivity. Many experience only visual changes. The absence of pain can be misleading and may delay diagnosis. Any unexplained change in vision deserves prompt evaluation.
Certain symptoms suggest a serious complication such as retinal detachment or severe inflammation. See a retina specialist or go to the emergency room immediately if you experience any of the following:
- A sudden curtain or shadow falling over part of your vision
- Severe or sudden blurring of vision
- A rapid increase in floaters
- Sudden loss of vision in one eye
Diagnosis and Testing
A retina specialist will begin with a detailed dilated eye examination. This involves widening the pupil with eye drops so the back of the eye can be viewed clearly. The specialist looks for signs of inflammation. These may include white or yellow spots on the choroid or retina, fluid under the retina, blood vessel changes, and scarring. Both eyes are examined because some forms of posterior uveitis affect both sides.
Advanced imaging helps the retina specialist assess the extent of inflammation and monitor the response to treatment. Common imaging tests include:
- Optical coherence tomography (OCT), which creates detailed cross-sectional images of the retina and can detect swelling, fluid, or structural changes
- Fluorescein angiography (FA), a test using dye injected into an arm vein to photograph retinal blood flow and reveal leaking or blocked vessels
- Indocyanine green angiography (ICG), which provides images of choroidal blood flow and is useful for detecting inflammation beneath the retinal pigment epithelium
- Fundus autofluorescence, a non-invasive method that highlights areas of damage to the retinal pigment epithelium
Because posterior uveitis is often linked to systemic disease or infection, blood tests and other laboratory studies may be necessary. Testing can screen for sarcoidosis, tuberculosis, syphilis, toxoplasmosis, and autoimmune markers. In some cases, a retina specialist may coordinate with a rheumatologist or infectious disease specialist. This helps identify or manage the underlying cause.
Treatment Options
Corticosteroids are a cornerstone of treatment for non-infectious posterior uveitis. They work by reducing inflammation quickly. For posterior and panuveitis, intravitreal corticosteroids (injected directly into the eye) tend to be more effective than periocular corticosteroids (injected around the eye). Periocular delivery, such as sub-Tenon triamcinolone acetonide, avoids certain risks. These include vitreous hemorrhage, endophthalmitis (a severe eye infection), and retinal detachment.
Ozurdex (dexamethasone intravitreal implant) is an FDA-approved option for non-infectious uveitis affecting the posterior segment. It releases medication gradually over approximately three to four months. Oral corticosteroids may also be used for severe or bilateral disease. However, they carry systemic side effects with long-term use.
For chronic conditions such as birdshot chorioretinopathy, retinal vasculitis, or multifocal choroiditis, corticosteroid-sparing therapy is typically started soon after diagnosis. Immunosuppressive medications can take several months to reach full effectiveness. Early initiation helps reduce long-term steroid dependence.
The FAST (First-Line Antimetabolites as Steroid-Sparing Treatment) uveitis trial found important results. Approximately 67% of patients taking methotrexate achieved steroid-sparing disease control at six months. About 57% in the mycophenolate mofetil group achieved the same (FAST Trial, 2020). The results showed the two drugs were comparable in effectiveness.
Adalimumab is currently the only FDA-approved biologic medication for noninfectious intermediate, posterior, and panuveitis. It works by blocking tumor necrosis factor (TNF), a protein involved in the inflammatory response. Adalimumab is typically used when other immunosuppressive therapies have not provided adequate control. It may also be chosen when patients cannot tolerate those medications.
When posterior uveitis is caused by an infection, the primary treatment targets the specific organism. For toxoplasmosis, this may involve antiparasitic medications. For tuberculosis-related uveitis, a full course of anti-tuberculosis drugs is necessary. Antiviral medications are used for herpes-related or CMV-related inflammation. Treating the infection is essential before or alongside anti-inflammatory therapy to avoid worsening the infection.
When posterior uveitis leads to choroidal neovascularization (abnormal new blood vessel growth), anti-VEGF (vascular endothelial growth factor) injections may be used. These medications block the signals that drive abnormal blood vessel growth and leakage. Avastin (bevacizumab), which is FDA-approved for cancer treatment and used off-label for eye conditions, has been used to manage inflammatory choroidal neovascularization. Other anti-VEGF agents such as Eylea (aflibercept) or Lucentis (ranibizumab) may also be considered.
What to Expect
Treatment for posterior uveitis is often a long-term process. Frequent follow-up visits with a retina specialist are necessary to monitor inflammation and check for medication side effects. Imaging tests such as OCT may be repeated at each visit to track changes in the retina. Some patients require treatment for months or years, particularly those with autoimmune-related choroiditis.
Without adequate treatment, posterior uveitis can lead to several vision-threatening complications. These include:
- Macular edema (swelling in the central retina), one of the most common causes of vision loss in uveitis
- Choroidal neovascularization, where abnormal blood vessels grow under the retina and can leak or bleed
- Cataracts, which can develop from inflammation or as a side effect of corticosteroid use
- Glaucoma (elevated eye pressure), which can result from inflammation or corticosteroid treatment
- Retinal scarring that may cause lasting blind spots
A 25% loss of visual acuity occurs in 43% of patients with posterior uveitis (Retina Today, 2017). This statistic highlights why early diagnosis and consistent treatment are so important. While some vision loss may be irreversible if scarring has occurred, many patients maintain functional vision with proper management. The goal of treatment is to control inflammation, prevent complications, and preserve as much vision as possible.
Living With Posterior Uveitis
Posterior uveitis often requires ongoing monitoring even when inflammation appears controlled. Flare-ups can occur without warning. A retina specialist may schedule regular check-ups every few weeks to every few months depending on the severity and type of uveitis. Keeping all scheduled appointments is one of the most important steps a patient can take to protect their vision.
Because posterior uveitis is frequently linked to systemic disease, patients may need to see other specialists. A rheumatologist can help manage autoimmune conditions like sarcoidosis or Behcet disease. An infectious disease specialist may be involved if tuberculosis or other infections are identified. Open communication among all treating providers helps ensure a coordinated approach to care.
Patients living with posterior uveitis should be aware of symptoms that may signal a flare-up. These include new floaters, increased blurriness, or light sensitivity. Wearing sunglasses outdoors can help manage photophobia. Taking medications exactly as prescribed is critical, especially immunosuppressive drugs that require consistent dosing. Stopping these medications without guidance from a retina specialist can lead to a sudden return of inflammation.
When to See a Retina Specialist
Any patient with unexplained visual symptoms such as persistent floaters, blurry vision, or blind spots should be evaluated. An optometrist or general ophthalmologist may detect signs of posterior uveitis during a routine eye exam. They can then refer the patient to a retina specialist for further evaluation and treatment. Posterior uveitis requires specialized expertise because the inflammation affects delicate structures at the back of the eye.
Sudden vision changes in a patient with known posterior uveitis should be treated as urgent. A rapid increase in floaters, new flashes of light, a shadow or curtain over part of the visual field, or sudden vision loss in one eye are all reasons to seek immediate care. These symptoms can indicate a serious complication such as retinal detachment or a severe inflammatory flare that needs prompt treatment to prevent irreversible damage.
Questions and Answers
Yes. Some forms of posterior uveitis, particularly those linked to autoimmune conditions like Vogt-Koyanagi-Harada syndrome or sarcoidosis, frequently involve both eyes. Other types, such as toxoplasmosis-related choroiditis, more commonly affect one eye at a time. A retina specialist will examine both eyes during every visit to check for bilateral involvement.
The duration of treatment varies widely depending on the underlying cause. Infectious posterior uveitis may resolve after the infection is treated, though monitoring continues for possible recurrence. Non-infectious autoimmune-related forms often require months to years of immunosuppressive therapy. Some patients need indefinite low-dose treatment to prevent flare-ups. A retina specialist will tailor the treatment plan to each patient's specific situation.
Long-term immunosuppressive therapy does carry risks. These include increased susceptibility to infections and potential effects on the liver, kidneys, or blood cell counts. However, these medications are carefully monitored through regular blood tests. The risk of uncontrolled inflammation causing severe vision loss often outweighs the risks of the medication. A retina specialist will weigh the benefits and risks for each patient and adjust treatment as needed.
Recurrence is common with many forms of posterior uveitis, especially autoimmune types. Some patients experience repeated flare-ups over the course of years. This is one reason why ongoing monitoring is so important even when the eye appears quiet. Early detection of a recurrence allows treatment to begin before significant damage occurs. Patients should report any new visual symptoms to their retina specialist promptly.