[Dacryocystography--conventional technic or digital subtraction technic?].

The lacrimal drainage systems of 92 patients were examined by a digital subtraction technique; 30 patients were examined additionally by a conventional technique, using films obtained during screening for the contrast injection. The digital subtraction dacryocystogram provided excellent demonstration of the lacrymal sac and of the tear ducts, but there is little diagnostic gain when compared with the conventional technique. Both methods are highly reliable. In view of its low radiation dose and rapid and simple course, conventional dacryocystography is regarded as the method of choice for routine examinations. The digital subtraction technique should be reserved for special problems.