AN ANATOMICAL BASIS FOR PRIMARY ACQUIRED NASOLACRIMAL DUCT OBSTRUCTION

Objective: To measure any sex size differences in the bony nasolacrima l drainage Systems in a normal, age-matched population. Methods: A ret rospective study of axial cut maxillofacial computed tomographic scans was conducted. Three levels of the bony nasolacrimal duct (NLD) syste m on the right and left sides were measured along the anteroposterior diameter. The data were analyzed using 2-tail t test, analysis of vari ance, and linear regression methods. Results: Scans from 71 adult pati ents (36 men and 35 women) were reviewed. Women were found to have a s maller bony diameter at the level of the lower fossa (P=.01) and the m iddle NLD (P=.06) compared with those of men. The adult inferior bony fossa increased in size with age in both men and women, while the midd le NLD increased in size in men only. No significant size difference w as found between the right and left side at any level. Conclusions: Si ze differences are found in measurements of bony nasolacrimal excretor y systems in men vs women. Women have significantly smaller dimensions in the lower nasolacrimal fossa and the middle NLD. The anteroposteri or dimension of the bony nasolacrimal canal at the fossa level enlarge d in both sexes, with age coinciding with osteoporotic changes through out the body. These quantitative anatomical observations preside a con tributory factor to explain the increased prevalence of primary acquir ed NLD obstruction in women.