Uveitis is commonly categorized into different types based on the part of the eye where the inflammation is concentrated.
- Anterior Uveitis: This is the most common type. The primary inflammatory activity occurs in the front part of the eye, the anterior chamber (the structure of the eye). Anterior Uveitis is also known as iridocyclitis. It typically presents with symptoms such as eye pain, light sensitivity, redness, and blurred vision.
The likelihood of recurrence within the first year after the initial episode is 24%. Anterior Uveitis can sometimes lead to adhesions between the iris and the lens, distorting the pupil.
The causes of Anterior Uveitis are diverse. The most common cause is idiopathic (meaning unknown) and accounts for about 40% of cases. The second most common cause is related to systemic diseases, particularly those in the group called spondyloarthropathies, which are chronic inflammatory diseases affecting the joints, especially in the spine and pelvis. Additionally, there may be manifestations in the eyes, skin, heart, and other organs. A significant number of patients carrying the genetic marker HLA B27 are prone to this type of uveitis. HLA B27 can also be found in healthy individuals but is much more common in those with spondyloarthropathies. Furthermore, HLA B27 is present in about half of the patients with acute anterior uveitis, even if they do not have any joint disease. Recurring attacks of acute anterior uveitis are typical in individuals with the HLA B27 marker, and each episode may affect a different eye
Other causes of anterior uveitis include infections, including viral infections like herpes viruses. Additional, but rare, infectious causes in Western countries are syphilis and cat-scratch disease. Another rare cause of anterior uveitis is drug-induced uveitis, specifically associated with medications used to treat osteoporosis, known as bisphosphonates. It is essential to identify these cases as stopping the medication usually leads to the resolution of uveitis
Pediatric Anterior Uveitis: Even children can develop uveitis, and the most common cause is juvenile idiopathic arthritis (JIA), which is more prevalent in girls. - Intermediate Uveitis: In this form of uveitis, the inflammatory response primarily affects the vitreous humor and often the peripheral retina as well. This condition has a chronic, prolonged course, often lasting for years. It typically presents with bilateral blurred vision or "floaters." Intermediate uveitis is characterized by vitreous, which involves cells and floaters in the vitreous humor. The primary reason for visual impairment is cystoid macular edema.
The causes of Intermediate Uveitis include infections like Toxocara canis (rare in Israel), cat-scratch disease, and autoimmune diseases, with sarcoidosis being the most common. Another rare but important cause is intraocular lymphoma, which can masquerade as uveitis. In these cases, a diagnostic workup would include MRI, lumbar puncture, and a vitreous biopsy.
When the cause of Intermediate Uveitis remains unknown, it is referred to as idiopathic, and the term Pars Planitis is used to describe the condition. - Posterior Uveitis: This type of uveitis primarily affects the back part of the eye, involving the choroid and retina. Posterior Uveitis is generally more severe and requires intensive treatment. One of the common causes of Posterior Uveitis is infection by the parasite Toxoplasma gondii, known as Toxoplasmosis. The infection can be acquired or congenital, and it tends to recur. Treatment involves a combination of antibiotics and steroids.
- Panuveitis: Panuveitis is an inflammation of all layers of the uvea and involves all parts of the eye. It is often associated with severe inflammation and can be vision-threatening. The causes, as in other types of uveitis, can be infectious, various autoimmune diseases, and more. In some cases, despite intensive investigation, the cause may remain unidentified.
Uveitis is a diverse group of inflammatory eye conditions that can impact various parts of the eye. Accurate diagnosis and identification of the underlying cause are crucial for appropriate management and treatment.