Numerized analysis of intubation dacryocystography of results in normal subjects

268 cases of normal lacrimal drainage systems（LDS）in 134 subjects were investigated with intubation dacryocystography（IDCG）and the results were evaluated for the first time in the way of numerized analysis.The normal ranges of X-ray anatomy of the main parts of LDS were presented and they may be used as a reference in clinical practice. It was shown by the results that LDS changes with age which are more obvious in the female especially in the elderly group,tending to develop narrowness or obstruction of LDS and include shortening of the distance between the canalicula and the vertex of the lacrimal sac,the narrowing of the diameters of the lower opening of the lacrimal sac,especially in the narrowest parts of both bony and membranous nasolacrimal canal. In the paper,the possible mechanism of the higher incidence of narrowing LDS in female was also discussed.