Sarcoidosis is a systemic inflammatory disease that causes the immune system to form small, inflammatory cell clusters called granulomas in various organs. When these granulomas develop in the eye, the condition is known as ocular sarcoidosis. Eye involvement is a frequent feature of the disease, and its presence can be the first sign of the broader systemic condition for many individuals.
Common Eye Manifestations
Uveitis, or inflammation of the uvea, is the most common way sarcoidosis affects the eyes, occurring in 30-70% of cases. The uvea is the middle layer of the eye, rich in blood vessels. Inflammation is categorized based on the specific part of the uvea affected. Anterior uveitis involves inflammation in the front part of the eye, leading to granulomatous keratic precipitates—cellular deposits on the cornea—and nodules on the iris.
Intermediate uveitis affects the vitreous humor, the gel-like substance filling the eyeball, and can cause characteristic “snowballs,” which are clumps of inflammatory cells. Posterior uveitis involves the retina and choroid in the back of the eye. Panuveitis is a term used when inflammation is present in all parts of the uvea. Each type of uveitis can present differently and affect vision.
Another common sign is the development of conjunctival nodules. These are small, pale, yellow bumps that form on the conjunctiva, the clear membrane covering the white part of the eye. These nodules are often asymptomatic and can be an important site for biopsy to confirm a diagnosis, as they represent clusters of granulomas.
Sarcoidosis can also impact the lacrimal glands, which produce the watery component of tears. Inflammation in these glands can disrupt tear production, leading to keratoconjunctivitis sicca, commonly known as dry eye syndrome. This condition can cause significant discomfort and affect the health of the cornea. Inflammation of the lacrimal drainage system can also cause excessive tearing, or epiphora.
More severe, though less frequent, manifestations include optic nerve and retinal disease. Granulomatous inflammation can directly affect the optic nerve sheath or the blood vessels of the retina. This can lead to complications like optic neuropathy or retinal neovascularization, where new, fragile blood vessels form and can bleed into the vitreous.
Recognizing the Symptoms
The symptoms of ocular sarcoidosis are related to the specific part of the eye that is inflamed. An individual with uveitis often experiences eye redness and pain, ranging from a dull ache to more intense discomfort. This inflammation can also cause significant sensitivity to light, a condition known as photophobia.
Vision changes are a primary indicator of ocular sarcoidosis. Blurred or decreased vision is a frequent complaint and can result from inflammation in the vitreous or macular edema. Patients may also notice floaters, which appear as dark spots or lines drifting through their field of vision. These floaters are often a sign of intermediate uveitis, caused by inflammatory cells casting shadows on the retina.
When the lacrimal glands are affected, a person might experience symptoms of dry eye, including a dry, gritty, or burning sensation. Paradoxically, some individuals may experience excessive watering of the eyes, known as epiphora. This can occur if the tear drainage system becomes blocked by inflammation.
The Diagnostic Process
Diagnosing ocular sarcoidosis can be a complex process because its symptoms often overlap with other eye conditions. The first step is a comprehensive eye examination by an ophthalmologist. During this exam, a slit lamp is used to provide a magnified view of the eye’s structures, allowing the doctor to identify signs of inflammation such as keratic precipitates, iris nodules, or vitreous cells.
Because ocular issues are often part of a systemic disease, a thorough systemic evaluation is necessary to support the diagnosis. This involves looking for evidence of sarcoidosis in other parts of the body. A chest X-ray or CT scan is commonly ordered, as granulomas are frequently found in the lungs and lymph nodes. Blood tests measuring angiotensin-converting enzyme (ACE) levels may also be conducted, although elevated levels are not exclusive to sarcoidosis.
The most definitive method for diagnosing sarcoidosis is a tissue biopsy that reveals the presence of noncaseating granulomas. These are the characteristic inflammatory cell clusters of the disease. Whenever possible, the biopsy is taken from the most accessible and least invasive site, such as the skin or lymph nodes.
Treatment Approaches
The primary goal of treating ocular sarcoidosis is to control inflammation, prevent structural damage to the eye, and preserve vision. Corticosteroids are the first-line treatment for managing the inflammation. Depending on the location and severity, they can be administered as topical steroid eye drops for anterior uveitis or as local injections for more persistent inflammation. For severe disease, systemic corticosteroids taken orally are prescribed.
For individuals who do not respond adequately to corticosteroids or who experience side effects from long-term use, immunosuppressive medications are a second-line treatment. Drugs such as methotrexate are used to modulate the immune system’s inflammatory response. These medications help reduce the reliance on steroids and provide long-term control.
Biologic drugs have emerged as a therapeutic option for severe or refractory cases of ocular sarcoidosis. These medications are more targeted, working on specific components of the immune pathway to reduce inflammation. Their use is reserved for situations where other treatments have failed to control the disease.
Managing ocular sarcoidosis requires a long-term commitment to treatment and consistent monitoring. Regular follow-up appointments with an ophthalmologist are necessary to assess treatment effectiveness, adjust medications as needed, and watch for potential complications. This ongoing care is essential to manage the condition and protect against vision loss.