In very rare cases following a unilateral eye injury, a condition called sympathetic ophthalmia can develop. This condition presents itself as a form of uveitis (eye inflammation), and it occurs when the body’s own immune system attacks first the injured eye and then the healthy one. At the time when sympathetic ophthalmia was first documented and named by 19th-century ophthalmologist William MacKenzie, it was generally treated by the application of leeches to the inflamed eye. This condition is indeed rare—no more than three cases occur out of any ten million penetrating eye injuries. To put it another way, sympathetic ophthalmia (or SO) occurs in 0.2 to 0.5 percent of non-surgical eye wounds, and less than .01 percent of surgical wounds. Despite its rarity, sympathetic ophthalmia has claimed the sight of a few notable people, possibly including Louis Braille, inventor of the braille system of writing now used by blind people all over the world. At the age of three, Braille injured his left eye while playing with an awl in his father’s workshop, and the infection that resulted from the wound spread to his right eye in a way that, to modern doctors, is suggestive of SO.
What Causes Sympathetic Ophthalmia, and How Does It Progress Over Time?
The cause of SO is not well understood, but it is believed that certain types of eye trauma (usually penetrating injury) bring parts of the eye into contact with the bloodstream in a way that excites the immune system. Under normal circumstances, the immune system does not come into contact with these tissues, and so it never “learns” to recognize them as part of the body. Within a few months following the trauma to one eye (or sometimes only a few days, or as long as a few years), the second eye will be attacked by the immune system, which responds to it as though it were foreign tissue, and both eyes will become inflamed. When a patient is attacked by his or her own immune system, it is called an autoimmune response. The eye that sustains the initial injury is known as the “exciting eye,” and the eye that develops the sympathetic inflammation is called the “sympathetic eye.” The inflammation generally attacks the uveal layer of the eye, causing pain and vision loss.
What Are Some Signs and Symptoms I Can Look for When Sympathetic Ophthalmia Develops?
There is usually no pain when this condition first sets in, but the individual suffering from SO will begin to experience blurred vision as the eye loses its ability to focus properly. Eventually the symptoms progress to include:
• Severe eye pain and redness in both eyes
• Extreme sensitivity to light (a condition known as photophobia)
• “Floaters” in the visual field
• Watery eyes
• Visual impairment, eventually leading to blindness
Under a microscope examination, the doctor may see clumps of inflammatory cells on the posterior corneal surface. These are called “mutton-fat” keratic precipitates. While there is no test that can detect the presence of SO with absolute certainty, these signs, combined with a medical history that includes the right kind of injury to the other eye, can give a doctor good reason to suspect sympathetic ophthalmia.
What Are My Treatment Options for Sympathetic Ophthalmia?
Enucleation—the removal of the entire injured eyeball—will be considered if the sight in the injured eye has been irretrievably lost. This extreme step will only be taken if it is deemed necessary to save the sight in the remaining eye. If the injured eye is removed within a week or two following the injury, the autoimmune response that causes sympathetic ophthalmia can be prevented. Once SO has started, however, there is no longer anything to be gained by removing the injured eye. If the sight of the injured eye can be preserved, or if medical intervention does not come in time to prevent the autoimmune response, then corticosteroids may be used to attempt to control the inflammation, and immunosuppressive therapy may ultimately be considered. This may include the use of T-cell inhibitor drugs such as Cyclosporine, which partially suppress immune system activity.