Posterior uveitis is an inflammatory condition affecting the back of the eye’s middle layer, the uvea. This inflammation specifically targets the choroid, a vascular layer providing oxygen and nutrients to the retina, and can also involve the retina itself. As this condition directly impacts structures responsible for vision, prompt medical evaluation is necessary to manage inflammation and preserve visual function.
Symptoms and Manifestations
Individuals experiencing posterior uveitis often notice changes in their vision. A common symptom is “floaters,” dark, string-like or spot-like shapes that drift across the field of vision. Vision may also become blurred or hazy, making it difficult to see clearly. Blind spots (scotomas) can develop, indicating specific areas of retinal involvement.
Unlike some other forms of uveitis that affect the front of the eye, posterior uveitis typically presents with minimal or no eye pain. Redness of the eye is often absent, which can sometimes delay seeking medical attention. The specific symptoms depend on the inflammation’s location, which may include choroiditis (choroid inflammation), retinitis (retina inflammation), or chorioretinitis (inflammation affecting both layers).
Associated Causes and Systemic Diseases
Posterior uveitis often arises from broader health conditions affecting the entire body. Non-infectious or autoimmune conditions represent a significant category of causes. For example, sarcoidosis, a disorder characterized by the growth of inflammatory cells in various organs, can lead to ocular inflammation. Behçet’s disease, a rare disorder causing blood vessel inflammation, often involves the eyes, leading to recurrent episodes of posterior uveitis. Vogt-Koyanagi-Harada (VKH) syndrome is another autoimmune condition where the body’s immune system mistakenly attacks melanin-producing cells, affecting the eyes, ears, skin, and brain.
Infectious diseases also account for many posterior uveitis cases. Toxoplasmosis, caused by the parasite Toxoplasma gondii, is a prevalent infectious cause and often results in chorioretinal scars. Tuberculosis, a bacterial infection primarily affecting the lungs, can disseminate and cause ocular inflammation, including posterior uveitis. Syphilis, a sexually transmitted bacterial infection, is another known cause of uveitis, sometimes presenting with a characteristic “salt-and-pepper” appearance on the retina. In 25% to 40% of cases, a specific underlying cause cannot be identified, and these are termed idiopathic cases.
The Diagnostic Examination
Diagnosing posterior uveitis begins with a comprehensive clinical assessment. A detailed patient history is gathered, including any symptoms experienced, their duration, and any relevant medical conditions or exposures. A dilated fundus examination is then performed using an ophthalmoscope, allowing the ophthalmologist to view the back of the eye (retina, choroid, and optic nerve) to identify signs of inflammation such as retinal swelling, lesions, or hemorrhages.
Specialized imaging tests provide further insights into the extent and nature of the inflammation. Optical Coherence Tomography (OCT) is a non-invasive imaging technique that generates high-resolution cross-sectional images of the retina, showing retinal swelling, fluid accumulation, or structural changes. Fluorescein Angiography involves injecting a dye into a vein, which circulates to the eye, allowing for detailed visualization of blood vessels and detection of leakage or abnormal blood flow patterns in the choroid and retina. To identify underlying systemic or infectious causes, blood tests and other laboratory investigations, such as chest X-rays or spinal fluid analysis, are often performed.
Therapeutic Interventions
Controlling inflammation and preserving vision are the primary objectives of treating posterior uveitis. Corticosteroids serve as the first line of treatment due to their potent anti-inflammatory effects. These medications can be administered orally, through local injections around the eye, or via long-acting surgical implants that slowly release medication over several months. The specific route and dosage depend on the severity and location of the inflammation.
For severe, chronic, or corticosteroid-unresponsive cases, additional therapeutic approaches are employed. Immunosuppressive medications, such as methotrexate or azathioprine, can be used to dampen the body’s overactive immune response. Biologic therapies, including agents like adalimumab or infliximab, target specific inflammatory pathways and are used for more challenging cases. If an infectious cause is identified through diagnostic tests, specific antimicrobial treatment, such as antibiotics or antiparasitic drugs, is initiated to eliminate the pathogen.
Potential Ocular Complications
Chronic or poorly controlled inflammation in posterior uveitis can lead to several long-term ocular complications. Macular edema, swelling of the macula (the central part of the retina responsible for sharp vision), is a frequent and vision-threatening complication. Sustained inflammation can also contribute to glaucoma, a condition characterized by increased eye pressure that can damage the optic nerve.
Cataracts, clouding of the eye’s natural lens, can also arise as a complication, often accelerated by inflammation and long-term corticosteroid use. In more severe instances, the chronic inflammation can weaken the retina, potentially leading to a retinal detachment, a serious condition where the retina pulls away from its underlying support tissue. Regular, long-term monitoring by an ophthalmologist is necessary to detect and manage these issues, helping to maintain ocular health.