Microscopic anatomy of the lower eyelid in asians.

PURPOSE: To study the microscopic anatomic relation of the capsulopalpebral fascia, orbital septum, and tarsus of the lower eyelid in Asians. The anatomic differences between the Asian and non-Asian upper eyelid have been well described by various authors, but the differences of the lower eyelid have not been well characterized microscopically. The microscopic anatomy of the lower eyelid in non-Asians was well studied, but in Asians, despite the presence of gross differences, there were very limited studies on the microscopic anatomy. A thorough knowledge of the Asian lower eyelid anatomy is essential for surgical exploration of the eyelid. It may also explain the higher prevalence of eyelid disorders such as epiblepharon and entropion in Asians.

METHODS: Ten normal Asian lower eyelids from 10 formalin-fixed cadavers (mean age, 67.5 years) were harvested and studied with light microscopy after staining with Masson trichrome.

RESULTS: There was no fusion of the orbital septum and the capsulopalpebral fascia at the lower border of the tarsal plate in 7 specimens and a very limited fusion of these tissues in 3 specimens. The average distance from the inferior tarsal border to the first observable smooth muscle nuclei of the inferior retractors was 1.44 mm. The average tarsal plate thickness was 1.36 mm and the average tarsal plate height was 4.12 mm.

CONCLUSIONS: The Asian lower eyelid anatomy differs from its non-Asian counterpart. There was no consistent fusion between the capsulopalpebral fascia and the orbital septum inferior to the inferior tarsal border. No extension of the capsulopalpebral fascia to the skin was observed. The average distance between the inferior retractors and the inferior tarsal plate was 1.44 mm in the normal Asian lower eyelid.