Saliva gland operation that could ease dry eyes
07:43 GMT, 29 May 2012
Transplanting saliva glands from the mouth to the eye could provide relief for severe dry eye syndrome.
The condition, also called keratoconjunctivitis sicca, is caused when the eye doesn’t produce enough of the protective layer called the tear film or it evaporates too quickly.
The tear film is made up of water, fats, proteins and infection-fighting cells — it lubricates the eye as well as keeping it clean and free of dust.
Red eyes: Transplanting saliva glands from the mouth to the eye could provide relief for severe dry eye syndrome
Without tear film, the eye surface dries out and can become inflamed and sore.
Vision may blur, and in very severe cases ulcers may start to form on the cornea, the transparent cover of the eye, causing it to tear or perforate.
Around one in 13 people in their 50s will experience dry eye syndrome, according to NHS statistics, with up to a third of those over 65 affected.
In many cases, there is no single identifiable cause, though hormonal changes linked to ageing and certain medications — such as some antidepressants, anti-histamines and beta-blockers — are known to make the condition worse.
Many sufferers are helped by a wide range of therapies including hot compresses, which can unblock tear ducts that may have become clogged, and eye drops (or artificial tears).
However, in severe cases the patient produces no tears at all — the new procedure has been developed to help them.
Saliva has a similar composition to the tear film, though it is slightly stickier and contains enzymes to help with the digestion of foods.
Whether these enzymes cause any adverse effect long-term is not yet known.
There are six saliva glands, around the size of a walnut, just under the jaw (the saliva is then carried up to the mouth through long tubes, or ducts).
During the surgery, one of these glands and sections of the duct are removed — the surgeon also takes some of the tiny arteries and veins that keep the gland nourished with blood and oxygen.
This gland is then implanted near the outer corner of the eye, close to the temple, where the tear glands are located.
'Vision may blur, and in very severe cases ulcers may start to form on the cornea, the transparent cover of the eye, causing it to tear or perforate'
The saliva gland duct is routed to the edge of the upper eyelid, along the same path as the tear ducts.
The operation takes six hours — research shows fluid starts to flow within 30 minutes of reconnecting the blood supply to the gland.
Once transplanted, the glands produce saliva to keep the eyes moist.
A clinical trial is underway at the Federal University of Sao Paulo, Brazil, where the therapy is being given to 19 patients with severe dry eyes.
Early research has shown that the surgery can be successful. A study of five patients at Washington University showed that symptoms were eased within a month of the procedure.
As a result of the surgery, one patient reduced the number of vials of artificial tears they used from 69 a day to one or two.
Three patients also found they were able to ‘milk’ the saliva gland by pressing their temple to get more lubricating fluid.
A team of surgeons from Napoli University and other centres in Germany, who treated patients with a severe form of dry eye linked to a type of conjunctivitis, also had good results.
‘Having dry eyes can be difficult and tiring,’ says Clara Eaglen, campaigns manager at charity Royal National Institute of Blind People (RNIB).
‘It is important to let your GP know if your eyes are feeling dry, gritty and sore. Though they can’t cure it, there are some treatments that can help.
‘Ongoing research is making steps towards finding treatments such as transplanting saliva glands, and we will follow developments with interest.’