The anatomical relationships between the lower eyelid retractors and the lacrimal caruncle: a microscopic study

To characterize the microscopic relationships between the lower eyelid retractors and the lacrimal caruncle and to define the possible role of the caruncle in the lacrimal drainage process.

Observational anatomic study.

Twelve eyelids with their orbital tissues (6 right and 6 left), fixed in 10% buffered formalin, were studied in 10 Asian cadavers (mean age at death: 77.1 years, age range: 62-92 years). An oblique incision in the harvested tissue specimen passed through the lower eyelid retractors and the lacrimal caruncle. The sliced specimens were stained with Masson's trichrome.

In all specimens, the lower eyelid retractors were shown to have direct connections to the lacrimal caruncle at the level of the medial horn of the lower eyelid retractors and to reach the medial rectus capsulopalpebral fascia. At this level, smooth muscle fibers were abundant both in the lower eyelid retractors and in the medial rectus capsulopalpebral fascia, which were symmetrically situated to the caruncle.

The lower eyelid retractors have direct connections to the lacrimal caruncle, at a level that is rich in smooth muscle fibers. These anatomic findings may confer functional advantages to the lacrimal drainage system.