After detaching medial canthal ligament, the periosteum over the lacrimal crest is divided to enter lacrimal fossa.
In external DCR, there is an external nasal scar and the possibility of injury to medial canthal ligament and orbicularis muscle.
Background: Rupture of the medial canthal ligament can be caused by many events.
The medial canthal ligament plays an important role in maintaining shape and function of the eyelids.
4) demonstrated in a cadaver study that the superficial buccal branches of the facial nerve pass around the inferior nasal margin of the orbicularis oculi muscle and cross over the medial canthal ligament
to innervate the procerus, the corrugator supercilii, and the orbicularis oculi muscles in the nasal periorbit in 94% of the specimens.
Medially, the canthal ligament splits and surrounds the lacrimal apparatus.
The lateral and medial canthal ligaments hold the lid to the surface of the anterior eye.
An 8 mm incision is made over the medial canthal ligament
close to the bridge of the nose and the ligament dissected carefully.
Through a modified medial canthal ligament
approach, a left radical ethmoidectomy and drainage of the orbital abscess were performed.
Endonasal endoscopic DCR has well known advantages over the standard external DCR like it avoids facial scarring, division of the medial canthal ligament
and disruption of the pump action of the lacrimal sac.
In the external DCR the medial canthal ligament
needs to be excised which is involved in the pumping action, affecting the lacrimal drainage system.
The mucoceles of the frontal sinus may disrupt the medial canthal ligament
and the orbital roof in which surgical interventions should include the reconstruction of these anatomic structures (9, 10).