Sarcoidosis is a systemic inflammatory disease that causes the formation of small, abnormal clusters of immune cells called granulomas throughout the body. These granulomas can develop in any organ, but they most frequently affect the lungs, lymph nodes, and skin. The eyes are one of the most common sites for this condition outside of the chest, impacting a significant number of patients. When the eyes are involved, the condition is referred to as ocular sarcoidosis, which can range from mild irritation to severe, vision-threatening inflammation. Recognizing and managing this inflammation swiftly is important for preventing permanent damage and preserving vision.
How Sarcoidosis Affects Eye Structures
The underlying pathology of ocular sarcoidosis involves the characteristic non-caseating granulomas, which are clusters of inflammatory cells that infiltrate and disrupt normal tissue function. These granulomas can form in nearly any part of the eye and its surrounding structures, leading to a variety of clinical presentations. The most frequent manifestation is uveitis, which is inflammation of the uvea, the middle layer of the eye (iris, ciliary body, and choroid).
Inflammation in the front of the eye, known as anterior uveitis, affects the iris and ciliary body, often causing symptoms like a red eye and light sensitivity. When the inflammation occurs in the back of the eye, it is termed posterior uveitis, involving the choroid and retina. Posterior involvement is concerning because the delicate tissues of the retina process light and transmit visual information.
A more severe, diffuse inflammation affecting all layers is called panuveitis, which carries a higher risk of complications. Sarcoidosis can also cause retinal vasculitis, where the blood vessels of the retina become inflamed, appearing as white cuffing or “candle wax drippings” around the vessels. Additionally, the disease can affect the optic nerve, causing an optic neuropathy that compromises the pathway connecting the eye to the brain.
Granulomas can form in the deeper layers of the eye, such as the choroid, or on the optic nerve head, leading to direct tissue destruction. Sarcoidosis can also involve the lacrimal gland, which produces tears, resulting in dry eye syndrome. Granulomas may also appear on the conjunctiva, the clear membrane covering the white of the eye and the inner eyelid.
Recognizing Symptoms of Ocular Sarcoidosis
The symptoms experienced by a patient depend heavily on the location and severity of the inflammation, and they can be either sudden or slow to develop. Anterior uveitis typically causes noticeable symptoms like eye redness, pain, and increased sensitivity to light (photophobia). Patients may also notice excessive tearing or general discomfort.
When the inflammation is located in the back of the eye, a person may experience floaters, which appear as small specks, dots, or strings drifting across the field of vision. These are caused by inflammatory cells and debris accumulating in the vitreous, the gel-like substance that fills the eye. Blurred vision is a common complaint resulting from inflammation clouding the vitreous or from swelling in the macula, the center of the retina.
Severe vision loss can occur if the optic nerve is involved or if the inflammation leads to swelling of the retina, called cystoid macular edema. Symptoms can be acute (appearing suddenly) or chronic (developing gradually). Some individuals also experience dry, burning, or gritty sensations due to reduced tear production from lacrimal gland inflammation.
Confirming the Diagnosis
Confirming that eye inflammation is due to sarcoidosis requires a comprehensive ophthalmic examination alongside evidence of the systemic disease. An ophthalmologist uses a slit lamp to examine the eye’s internal structures for characteristic signs. A classic finding is the presence of large, waxy deposits of inflammatory cells on the inner surface of the cornea, referred to as “mutton fat” keratic precipitates.
The specialist may also look for nodules on the iris or in the drainage angle of the eye, which are visible clusters of granulomas. For the posterior segment, a dilated fundus examination is performed to look for inflammation of the retinal veins (periphlebitis) or the presence of snowball-like opacities in the vitreous. Advanced imaging tools, such as fluorescein angiography or Optical Coherence Tomography (OCT), detect subtle vascular leakage or macular swelling.
Since ocular sarcoidosis is a manifestation of a systemic disease, the diagnosis is supported by tests looking for involvement elsewhere in the body. Systemic tests often include a chest X-ray or CT scan to look for enlarged lymph nodes (bilateral hilar lymphadenopathy), a common sign of sarcoidosis. Blood tests measuring Angiotensin-Converting Enzyme (ACE) or serum lysozyme can also be supportive, though they are not definitive alone.
The most definitive way to confirm sarcoidosis is through a biopsy showing the non-caseating granulomas, although this is not always performed on the eye itself. If visible, a biopsy of a conjunctival or skin lesion is less invasive and provides the necessary tissue confirmation. In many cases, the diagnosis of ocular sarcoidosis is made by combining characteristic eye findings with strong evidence of systemic involvement, even without a tissue biopsy.
Treatment Strategies for Eye Sarcoidosis
The primary goal of treating ocular sarcoidosis is to reduce inflammation, prevent structural damage, and preserve vision. The strategy is tailored to the location and severity of the inflammation, starting with the least invasive options. For inflammation limited to the front of the eye (anterior uveitis), the first-line treatment involves topical corticosteroid eye drops, administered frequently to suppress the immune response.
These drops are effective for surface inflammation but may not penetrate deeply enough to treat posterior involvement. For inflammation in the back of the eye, such as posterior uveitis or optic nerve involvement, systemic treatment is required. This often begins with oral corticosteroids, such as prednisone, which are powerful anti-inflammatory medications that reach the deeper structures of the eye.
Higher doses of oral steroids may be necessary to manage severe conditions, like inflammation of the optic nerve. However, because long-term steroid use carries a risk of complications (like glaucoma and cataracts), doctors aim to reduce the dosage quickly. To achieve this, steroid-sparing immunosuppressive agents are often introduced for patients with chronic or severe disease.
Medications help control the immune response, allowing the systemic steroid dose to be lowered or discontinued. These include:
- Steroid-sparing immunosuppressants (e.g., methotrexate, azathioprine, or mycophenolate mofetil).
- Biologic agents (e.g., TNF-alpha inhibitors like infliximab or adalimumab) for cases unresponsive to conventional immunosuppressants.
Specific complications like cystoid macular edema may also be treated with regional therapies, such as corticosteroid injections directly into or around the eye.