Spontaneous NLD resolution in infants coincides with duct expansion

The authors studied changes in the dimensions of the nasolacrimal duct (NLD) in relation to the orbit and nose in children between 2 weeks and 34 months of age by retrospectively viewing consecutive series of facial computed tomography (CT) scans. They found that increases in NLD height, diameter and volume occur primarily before six months of age.

They conclude that spontaneous resolution of NLD obstruction in normal infants is coincident with elongation, limited radial extension and the resulting volume expansion of the NLD. The authors propose that increased hydrostatic pressure resulting from volume expansion of the NLD combined with central cavitation of the epithelial core underlies the spontaneous resolution of congenital NLD obstruction.

They reviewed records for consecutive cases with CT facial series with 0.50- to 0.625-mm resolution and no history of NLD abnormalities seen at one pediatric craniofacial clinic during a 16-month period. They identified 38 children for inclusion in the study.

The authors found that the height of the bony NLD increases 1.8-fold, the average diameter increases 1.4-fold and the volume increases 4.6-fold between 2 weeks and 34 months of age. NLD dimensional increases are nonlinear, with most of the increase occurring in the first six months of life. The increase in height of the NLD is highly correlated with postnatal growth of the maxilla.

The results may explain the resolution of congenital NLD. However, the authors do not mention how many CTs were performed for each patient and at what intervals. Their results are actually an extrapolation of their findings. The CTs were performed for various orbital disorders, such as cranial synostosis, which may have some effect on NLD development.