The medial canthal tendon (medial palpebral ligament) connects the tarsal plates of the upper and lower eyelids to the medial orbital wall. It has an anterior limb (attaching to the anterior lacrimal crest of the maxilla) and a posterior limb (attaching to the posterior lacrimal crest of the lacrimal bone), with the lacrimal sac lying between these two limbs. The medial canthal angle is maintained by the tendon and determines the position of the inner corner of the palpebral fissure.
Anchors the medial ends of both tarsal plates to the medial orbital wall, maintains medial canthal position, and forms the Y-shaped structure that cradles the lacrimal sac between its anterior and posterior limbs.
Medial canthal tendon laxity or detachment produces telecanthus (increased intercanthal distance) and medial canthal drift, seen in trauma, tumour resection, and aging. Canthoplasty re-anchors the tendon to the medial orbital wall. In dacryocystorhinostomy (DCR) for nasolacrimal duct obstruction, the medial canthal tendon is identified and the lacrimal sac is identified between its limbs. Transnasal or external DCR both require knowledge of the anterior limb attachment at the anterior lacrimal crest.
NOE complex fractures detach the medial canthal tendon from the anterior lacrimal crest producing traumatic telecanthus with increased intercanthal distance and rounded medial canthal angle; transnasal canthopexy with a wire suture through the nasal bones posterior to the lacrimal sac restores canthal position.
