Microscopic findings of lateral tarsal fixation in Asians

To identify microscopically lateral tarsal fixation in Asians.

Specimens from 19 postmortem lateral eyelids and orbits of 11 Asians (11 right, 8 left; aged 45-96 years at death) were used. Samples damaged on sectioning and samples without tarsal plates were excluded. The samples were fixed in 10% buffered formalin and examined under a microscope. Two levels of tarsus were observed in the upper and lower eyelids, suggesting the possibility of different means of fixation. The first and second sections, which were incised parallel to the eyelid margin, were obtained at 1 mm and 5 mm from the upper eyelid margin, and at 1 mm and 3 mm from the lower eyelid margin. The sections were stained with Masson trichrome.

The first sections of all upper eyelids and those of the lower eyelids except one showed tarsal fixation by both the lateral rectus capsulopalpebral fascia (lr-CPF) and the tendon-ligament complex of the lateral canthal tendon (LCT), which in several cases received the muscle of Riolan. The second sections of all upper eyelids showed fixation by the lr-CPF and the ligamentous part of the LCT. The second sections of the lower eyelids were mostly similar to the second sections of upper eyelids, though some showed only ligamentous fixation. The lr-CPF in all cases included a small amount of smooth muscle fibers.

The lateral aspect of the tarsus is supported by the lr-CPF and the LCT, which in some cases includes the muscle of Riolan.