BACKGROUNDBlepharophimosis ptosis epicanthus inversus syndrome (BPES) is a rare congenital ophthalmic disorder, characterized by congenital eyelid malformation including bilateral ptosis, shortening of the horizontal eyelid fissure, epicanthus inversus, and increased distance between the inner canthi. In this research, we studied the histological structure and ultrastructure of medial canthal ligament of patients with BPES.

METHODSThirty patients with BPES who received plastic surgery at the Zhongshan Ophthalmic Center from March 2006 to January 2008 were studied. There were 17 males and 13 females with an average age of (8.73 +/- 3.37) years (3 - 31 years). The medial canthal ligaments of patients were collected during the plastic surgery to analyze the histological structure by hematoxylin and eosin (HE), Congo red, van Gieson's (VG), Masson trichrome and aldehyde-fuchsin staining. The ultrastructures of the medial canthal ligaments were also analyzed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fifteen samples of medial canthal ligament from healthy persons with an average age of (9.02 +/- 3.12) years (6 - 30 years) were collected as a control group.

RESULTSMorphological and histological study showed that the medial canthal ligaments of BPES patients were composed of collagen fibers, a few elastic fibers and striated muscles. The collagen fibers assemblies were disorganized and the fibrous connective tissues were undergoing hyaline degeneration. The karyopycnosis of fibroblasts was located among the collagen fibrils and the numbers of fibroblasts were decreased. Ultrastructural study with SEM showed that the collagen fibers were larger than normal, irregular and loose. Parts of the collagen fibers were broken and had a coarse surface. Ultrastructural study with TEM showed that the fibroblasts had less cytoplasm, fewer organelles and the nucleus displayed pyknosis.

CONCLUSIONSThe medial canthal ligament in BPES patients is composed chiefly of collagen fibers. The collagen fibers of medial canthal ligaments in BPES patients are disorganized and hyaline degeneration is present. The study revealed that the medial canthal ligament of BPES patients might have congenital dysplasia.