Intermediate uveitis is a specific type of eye inflammation that affects the middle layer of the eye, known as the uvea. While it can occur at any age, it is commonly seen in individuals between 20 and 60 years old, including children. If left unaddressed, intermediate uveitis can lead to various complications, potentially affecting vision.
Understanding Intermediate Uveitis
Intermediate uveitis specifically targets the vitreous, which is the clear, jelly-like substance filling the center of the eye, and the peripheral retina, the light-sensitive tissue at the back of the eye responsible for side vision and night vision. It is also known by other terms such as pars planitis, posterior cyclitis, and hyalitis.
Common signs and symptoms associated with intermediate uveitis often include the appearance of floaters, which are small dark spots or lines that seem to drift across a person’s field of vision. Individuals may also experience blurred or cloudy vision. Unlike some other types of eye inflammation, intermediate uveitis typically does not cause significant eye pain or redness. In some instances, particularly in children, symptoms may be mild or even absent.
Identifying Potential Causes
In many cases, the specific cause of intermediate uveitis remains unknown, and it is then referred to as idiopathic intermediate uveitis or pars planitis. This idiopathic form accounts for more than 50% of cases. However, intermediate uveitis can be linked to various underlying systemic conditions or infections.
Systemic diseases frequently associated with intermediate uveitis include multiple sclerosis and sarcoidosis. Multiple sclerosis is a neurological condition, and intermediate uveitis can sometimes be its first manifestation, occurring in about 3% to 27% of patients with multiple sclerosis. Sarcoidosis, an inflammatory disease affecting multiple organs, is another common associate, with approximately 2% to 10% of intermediate uveitis patients developing sarcoidosis. Other systemic conditions that may be linked include inflammatory bowel disease, rheumatoid arthritis, and certain types of lymphoma.
Infectious agents can also trigger intermediate uveitis, though this is less common, accounting for approximately 4% of cases. Examples of bacterial infections linked to the condition include Lyme disease, syphilis, and tuberculosis. Viral causes can involve Epstein-Barr virus, herpes simplex virus, varicella-zoster virus (which causes shingles), and hepatitis C. Parasitic infections such as toxoplasmosis and toxocariasis are also potential culprits.
Diagnostic Methods and Treatment Options
Diagnosing intermediate uveitis involves a thorough eye examination by an ophthalmologist, who will assess the patient’s visual acuity and examine the internal structures of the eye. A slit-lamp examination allows the doctor to view the front of the eye magnified, while ophthalmoscopy, after dilating the pupil, provides a detailed view of the back of the eye, including the retina and vitreous. During this examination, inflammatory cells suspended in the vitreous, sometimes appearing as “snowballs,” and white exudates called “snowbanks” on the pars plana (a part of the ciliary body) may be observed.
Beyond the eye exam, other tests may be necessary to identify an underlying cause, especially if a systemic condition or infection is suspected. These can include blood tests to check for infections or markers of autoimmune diseases. Imaging tests, such as optical coherence tomography (OCT), are used to map the retina and choroid, helping to detect swelling like cystoid macular edema. Fluorescein angiography, which involves injecting a dye into the bloodstream to highlight blood vessels in the eye, can reveal leakage from inflamed vessels. In some complex cases, a diagnostic vitrectomy, a surgical procedure to obtain a sample of the vitreous fluid, may be performed to rule out malignancy or persistent infection.
Treatment for intermediate uveitis focuses on controlling inflammation and preventing vision loss. Corticosteroids are the first-line treatment for non-infectious cases. For localized inflammation, periocular injections (around the eye) or intravitreal injections (directly into the vitreous) of corticosteroids like triamcinolone acetonide or dexamethasone implants are common. Oral corticosteroids, such as prednisone, are used for more widespread or severe inflammation, typically starting at a dose of 0.5-1 mg/kg daily and then gradually tapered.
When corticosteroids alone are insufficient, or if long-term steroid use is a concern due to potential side effects, immunosuppressive drugs may be introduced. These steroid-sparing therapies reduce inflammation. Commonly used immunosuppressants include antimetabolites like methotrexate, azathioprine, and mycophenolate mofetil. Calcineurin inhibitors such as cyclosporine and tacrolimus are also utilized. Biological response modifiers, like adalimumab, are increasingly employed for non-infectious intermediate, posterior, and panuveitis that are resistant to conventional therapies. The choice of treatment depends on the severity of the inflammation, its underlying cause, and the patient’s overall health.
Managing the Condition and Its Impact
Intermediate uveitis is often a chronic condition. Around 60% of cases follow a prolonged course with recurring inflammation. This long-term nature necessitates ongoing monitoring and management to prevent potential complications.
If left untreated, intermediate uveitis can lead to severe ocular complications. One of the most common complications is cystoid macular edema (CME), which is swelling of the macula, the part of the retina responsible for sharp, central vision. CME is a leading cause of vision loss in intermediate uveitis patients.
Other potential complications include cataracts, which are clouding of the eye’s lens and can occur in 15% to 50% of affected eyes. Glaucoma, characterized by increased pressure inside the eye that can damage the optic nerve, can also develop. Less common but severe complications include retinal detachment, vitreous hemorrhage, and epiretinal membrane formation. Regular follow-up appointments, often every three months, are important for early detection and timely intervention for these complications.