Anatomical study of the extraocular check ligament system

To clarify the gross anatomy structure of the check ligament of the palpebra superior in relation to congenital blepharoptosis operation.

Seven fixed and three fresh cadavers of Chinese adults (between 53 and 76 years old; 5 males and 5 females) were used. Gross dissection was performed on fourteen eyes in seven cadavers. In three fixed cadavers, six bulbus oculi received histological sections for immunohistochemical tests.

Below the levator upon the superior rectus, the check ligament described by Lockwood is found. It extends bilaterally and attaches to the orbital wall behind the inner and lateral canthus tendon. Between the inferior obliquus and the inferior rectus, we also found a sheath structure similar to the check ligament extending bilaterally to the orbital wall. These two structures form an annular fascial system surrounding the eyeball. The medial half of the fascial sheath is tenacious, and the immunohistochemical test proves that smooth muscle cells are found in this part.

We call this whole fascial sheath surrounding the circumocular muscle the Extraocular Check Ligament System (ECLS), and it plays a restricting and checking role in the movement of the eyeball. Surgeons should be aware of the ECLS when performing ptosis or other blepharal surgery.