Uveitis, or inflammation of the uveal tract (iris, ciliary body, and choroid), is the most common ophthalmic sign of sarcoidosis.
If the inflammation is intense, the conjunctiva around the corneal border may be red ("ciliary flush"). But the inflammation is usually so indolent that the patient has minimal symptoms and there are no signs except with the slit lamp biomicroscope.
Biomicroscopy shows manifestations of disruption of the blood-aqueous barrier. Protein and lymphocytes leak into the anterior chamber of the eye. The high protein content makes the biomicroscope beam smokey rather than clear.
As the lymphocytes float into the beam, they produce a sudden glint of light ("Brownian movement"). The floating lymphocytes may alight on the back surface of the cornea to form gray-white clumps that resemble mutton fat ("").
As inflammation continues, the iris sticks to the anterior surface of the crystalline lens ("") or to the trabecular meshwork ("anterior synechiae") in the anterior chamber angle where the aqueous drains out. These adhesions, or synechiae, may be visible with a penlight as distortions of the normally round pupil. Sometimes granulomas form as round nodules on the iris surface.
If the choroid is attacked in sarcoidosis, lymphocytes appear in the vitreous cavity, and if the retina becomes involved, .
Other ophthalmic signs
Lacrimal gland infiltration is found in about 15% and conjunctival granulomas in 5%. The optic nerve can be involved as a part of a meningitis, as can the ocular motor nerves.
What to do?
The eye is a good place to look for signs of sarcoidosis because it, or its surrounding tissues, will be involved in 25% of cases. (After the lungs and lymph nodes, it is the third most commonly involved organ.)
Rarely are the ocular manifestations dramatic enough to bring the patient to the doctor before a systemic diagnosis is suspected.
Untreated, these ocular abnormalities can lead to blindness.
Treatment of uveitis consists of topical and systemic corticosteroids. Do not order a conjunctival biopsy to confirm a diagnosis of sarcoid in patients without any visible ocular manifestations because it has a negligible yield.