Sarcoidosis is a chronic inflammatory disease that can affect one or more organs and tissues throughout the body. It is characterized by clumps of inflammatory immune cells, called granulomas, that accumulate within affected tissues and organs. This causes further inflammation, with swelling leading to tissue damage and preventing organs from working as they should.
In around 50 percent of sarcoidosis cases, the disease affects the eyes and is called ocular sarcoidosis. Neurosarcoidosis, where the disease affects the nervous system, can also affect vision by damaging the optic nerve.
What is ocular sarcoidosis?
Ocular sarcoidosis can cause inflammation and damage to any part of the eye, due to the buildup of granulomas. Uveitis is the most common type of eye involvement in sarcoidosis. But other complications are known, including:
- Inflammation of the lacrimal glands, or tear-producing glands
- Orbital disease, or inflammation of the muscles, nerves, and blood vessels surrounding the eye
- Changes to the eyelid and eye surface, including a thickening of the lid and the formation of nodules caused by granuloma buildup on the conjunctiva, the membrane covering the eye and lining the eyelid
One of the most common complications of ocular sarcoidosis is uveitis, the inflammation of the middle layer of the eye, or the uvea. The uvea includes the iris, the ciliary body (which controls the shape of the lens), and the choroid (the eye’s blood vessels). Uveitis can also affect surrounding areas, including the lens, retina, optic nerve, and the vitreous (the liquid-filled space inside the eye).
Uveitis can be:
- Anterior, affecting only the front of the eye, such as the iris
- Intermediate, mostly affecting the vitreous
- Posterior, affecting the back of the eye, such as the retina and choroid
- Affecting most or all areas of the eye simultaneously, and called panuveitis
Anterior uveitis is the most common form of uveitis in ocular sarcoidosis, but not the only form. Uveitis may be acute, where it develops suddenly for a limited time, or chronic, with repeated episodes of worsening — for example, a flare once treatment has ended, following a period of inactivity.
Symptoms of ocular sarcoidosis
Common symptoms of ocular sarcoidosis include blurred vision or vision loss, light sensitivity (photophobia), floaters (black spots or lines in vision), dry or itchy eyes, red eyes, burning sensation in the eyes, or pain in the eyes. These may precede or occur alongside other common symptoms of sarcoidosis.
Diagnosis of ocular sarcoidosis
Diagnosis of ocular sarcoidosis can be complex, and multiple tests may need to rule out other conditions.
If a patient has a diagnosis of sarcoidosis and also shows eye symptoms, then ocular sarcoidosis is likely.
A diagnosis will normally involve an eye exam, as there are several characteristics that are frequently present in ocular sarcoidosis. These include nodules on the conjunctiva and iris, clumps of cells referred to as mutton-fat keratic precipitates (KPs) on the eye, or opaque patches also known as “snowballs” in the vitreous.
An eye test called the Schirmer test may be used to confirm the presence of inflammation in the eye, especially in the lacrimal glands. This involves holding a piece of blotting paper to the eye to test for reduced moisture and tear production.
If there are nodules on the conjunctiva, then a small sample (biopsy) may be taken from them for testing, as this can help diagnose ocular sarcoidosis.
Treatment of ocular sarcoidosis
There is currently no cure for ocular sarcoidosis, but there are therapies to manage inflammation and ease symptoms.
Mild anterior uveitis may be treated with eye drops containing corticosteroids, such as prednisone or Durezol (difluprednate), to reduce inflammation. These can also help manage lacrimal gland and orbital inflammation. Medicines called topical cycloplegics, such as cyclopentolate or atropine, work to dilate the pupil and prevent muscle spasms and may be given alongside corticosteroids to reduce pain.
More severe anterior uveitis, and intermediate, posterior and pan-uveitis may be treated with systemic steroids, which can be administered by mouth, through an injection into the eye, or rarely, via a time-release capsule implanted in the eye. This may be accompanied by other therapies to suppress the immune system, as these may reduce the buildup of granulomas.
Patients who are intolerant or not responding to corticosteroids may also be given medications that suppress the immune system and reduce inflammation. However, they can leave the patient vulnerable to infection. Examples include methotrexate, CellCept (mycophenolate mofetil), Imuran (azathioprine), and cyclosporine.
If cataracts have developed, surgery may be required once any inflammation is under control.
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