Inclination of the superomedial orbital rim in relation to that of the nasolacrimal drainage system.

The influence of the height of the superomedial orbital rim on the ease of nasolacrimal intubation has not been investigated. The authors measured the inclination of the height of the superomedial orbital rim and the nasolacrimal drainage system in 46 sides of Japanese cadavers. The inclinations to the coronal plane of the lacrimal sac and the nasolacrimal duct were measured. A straight probe was inserted into the lacrimal sac and allowed to rest on the superomedial orbital rim. The angle made by this probe and the coronal plane, defined as the inclination of the height of the superomedial orbital rim, was measured. The lacrimal sac was inclined 27.2 degrees +/- 7.6 degrees, the nasolacrimal duct was inclined 22.5 degrees +/- 9.7 degrees, and the height of the superomedial orbital rim was inclined 26.1 degrees +/- 9.1 degrees. For the height of the superomedial orbital rim-nasolacrimal duct angle, there were 33 sides with the anterior type and 13 sides with the posterior type. These results indicate that the height of the superomedial orbital rim may affect the ease of nasolacrimal intubation.