The lateral canthal tendon (lateral palpebral ligament) connects the lateral ends of the upper and lower tarsal plates to the lateral orbital wall at Whitnall tubercle, approximately 2-4 mm inside the lateral orbital rim. It is a Y-shaped structure whose upper and lower arms receive the upper and lower tarsal plates and fuse to attach to the tubercle. It maintains the lateral canthal angle and the position of the outer corner of the palpebral fissure.
Anchors the lateral ends of the tarsal plates to the lateral orbital wall, maintains lateral canthal position and the lateral canthal angle, and provides lateral support to the lower eyelid preventing ectropion.
Lateral canthal tendon laxity is the primary cause of involutional ectropion and lower eyelid malposition in the elderly. Lateral canthal tightening procedures (lateral tarsal strip, lateral canthoplasty) shorten and re-anchor the tendon to the lateral orbital wall at Whitnall tubercle. In lower eyelid reconstruction after tumour resection, the residual lateral canthal tendon stump is used to anchor the reconstructed lower lid. Orbital decompression for Graves orbitopathy may require lateral canthotomy and cantholysis of the inferior limb of the lateral canthal tendon.
Age-related attenuation of the lateral canthal tendon allows the lower lid margin to evert from the globe, producing ectropion with chronic exposure keratopathy and epiphora; lateral tarsal strip canthoplasty shortens the tendon and re-anchors it posterior to the lateral orbital rim restoring lower lid apposition.
