[The value of digital subtraction dacryocystography].

Dacryocystography is a standard technique for the visualization of the lacrimal pathways. In 1974, Lloyd et al. first described manual subtraction of dacryocystograms. Digital subtraction dacryocystography has definite advantages compared to the conventional dacryocystograms and manual subtraction. Besides the clearly superior topographic display, it also provides information about the functional status of the nasolacrimal pathway. Even though slightly more time consuming, this examination is well justified by the superior quality of the depiction of fine topographic details. Other advantages are the kinetic evaluation of tear flow, digital image analysis and the relatively low radiation dose.