Saliva Gland Helps Dry Eyes -- Research Summary
STEVENS-JOHNSON SYNDROME: Stevens-Johnson syndrome is a poorly understood allergic problem, where the body generates antibodies that cause side effects. In most cases, the outer lining of the body (the skin) and also the lining covering the eyes are affected. Many patients end up with damage to this lining, which results in scarring and even vision loss. The tiny ducts that bring tears from the tear gland onto the surface of the eye become scarred and closed off, losing function. Tears are made, but cannot get to the eyes, resulting in severely dry eyes.
DANGERS OF DRY EYES: Severely dry eyes are uncomfortable for the patient, as they easily become scratched and sore. More importantly, the surface of the eye allows light to get to the back of the eye (the retina) where the sensory cells are located. For that to happen, the light has to be able to fully go through the membrane in the front of the eye. But if there is scarring, the light becomes fuzzy, losing focus as it travels through. Those with exposed, dry eyes can have a gradual erosion of their vision due to a loss of ability to transmit the light into the actual eye socket. For patients, it means impaired vision and even eventual blindness. Loss of tear duct function can mean the eye loses its ability to protect itself. Tears have a cleansing function, as they flush out dust and debris. Without that cleansing, the eye can become infected and deteriorate.
TREATMENT: Surgical intervention could be done to allow the light to properly reach the retina. However, the eyes must be moist for it to work.
NEW FIX: Doctors at Washington University School of Medicine in St. Louis have performed what they say is the first procedure in the country that transplants a salivary gland to the eye. The gland under the jaw produces 15 percent to 20 percent of one's saliva and poses the fewest risks to transplant. The operation can be complicated and time-consuming because when tissue is transferred from one place in the body to another, it must have a blood supply. Doctors must find certain blood vessels, dissect them and keep them as a unit with the gland. The duct that normally brings saliva from the gland to the mouth must be removed but kept attached to the gland. Doctors create a little pocket in the temple area with an incision above the forehead. They remove some non-essential muscle to make a space for the gland and install it in the temple area. A slight bulge is created that hair can cover. Then, doctors can make a tunnel under the skin that allows the duct to get to the top of the eye. They make a small incision in the lining of the eye and attach the duct so that the secretions spill out onto the surface of the eye. Their last step is hooking up the blood vessels. The salivary gland has a nerve that tells it to make saliva when a person is hungry. That nerve is not transferred. Therefore, "saliva tear" production does not increase when a person is hungry, but the downside is that saliva production may be low because nothing is telling the gland to make it. However, Washington University otolaryngologist Randal Paniello, M.D., says there seems to be a suitable baseline rate of steady saliva production with the remaining glands in the mouth.
SUCCESS: Washington University doctors have now performed the procedure on two patients. It's been done on a limited basis in four other countries and, so far, has shown about a 90-percent success rate. The procedure can also potentially improve vision, as moisture in the eye can make a difference in the eye's tissue properties. More importantly, it opens up the chance of having sight-restoring surgery that needs moisture in the eye to be done successfully.
SAFETY: Dr. Paniello says saliva in the duct is sterile and clean. It only becomes contaminated when "it gets into the dirty mouth." He says people may wonder if there are components in the saliva that are bad for the eye. He says although there is an enzyme in the saliva that is believed to start the digestive process, it appears to be mild enough so that it would not potentially digest the eye surface.
CANDIDACY: Although Dr. Paniello says the implications of this procedure are very exciting, he cautions it is not for every patient with severely dry eyes. He says some conditions that cause dry eyes also cause dried-up saliva.
This article was reported by Ivanhoe.com, who offers Medical Alerts by e-mail every day of the week. To subscribe, go to: /newsalert/.
If you would like more information, please contact:
Diane Duke Williams
Washington University School of Medicine
4444 Forest Park, Campus Box 8508
St. Louis, MO 63108-2212