In a third of cases, it is caused by glands in the eyelids, which secrete oils. The problem occurs when these oils are too thick and waxy - it's usually an age thing.
As a result, the layer of water that coats the eyes evaporates too quickly, leaving them dry and inflamed. Symptoms include a chronic stinging and a gritty, burning, and itching feeling.
The new Blephasteam goggles deliver steam directly into the eyes, melting the waxy oil in the eye to improve its natural oil secretions.
Their inventor, the British eye specialist John Fuller, came up with the idea when he was persuaded to try a steam bath while visiting his brother Tom in New Zealand.
Tears are formed of three layers, one of which is oily.
"Like all oily substances, when heated this layer melts, creating better lubrication," the Daily Mail quoted Fuller as saying.
Fuller persuaded Tom, who was a design engineer, to create the prototype for the Blephasteam goggles that were then used in clinical trials at Dorset County Hospital, in Dorchester (where Fuller is consultant ophthalmic surgeon).
That was in 2001. Soon afterwards the goggles were being jointly produced by a UK company, Spectrum, and Laboratoires Thea in France.
They look a bit like swimming goggles but are made from medical-grade rubber and cost 200 pounds.
Because of the low heat, the amount of moisture produced doesn't steam up the lenses so user can watch TV or read while wearing them.
"The great bonus is that the goggles deliver therapy naturally, without the need for chemicals," Fuller explained.
Fuller, who trained at Moorfields Eye Hospital, says he has used the device on hundreds of his patients, with good results.