The canthal tendons maintain the shape of the palpebral fissure and also maintain lid apposition to the globe, important for proper corneal lubrication and tear drainage.

The medial canthus has origins at the anterior and posterior lacrimal crests that fuse temporal to the lacrimal sac, enveloping the lacrimal sac. The medial canthus then divides into upper and lower segments that attach to the tarsus of the upper and lower lid.

The medial canthus is involved in the lacrimal pump mechanism and intimately associated with the lacrimal sac.

The lateral canthal tendon originates at the lateral orbital tubercle 4 to 5 mm posterior to the lateral orbital rim. This provides a posterior vector opposing the lid to the globe. The lateral canthal tendon then splits into superior and inferior segments that attach to the tarsal plates (FIG 1).

The lateral canthal tendon inserts approximately 2 mm higher than does the medial canthal tendon. This creates a superior tilt to the palpebral fissure moving laterally.

The orbital septum overlies the lateral canthus as it approaches the orbital rim and acts as a “superficial lateral canthus,” which can be used for suspension in mild cosmetic defects.¹

Common conditions that may cause eyelid laxity or malposition including congenital facial clefting (ie, Tessier 2 to 12 clefts), amniotic band syndrome, congenital eyelid malposition, or deformities resulting from other etiologies including trauma and cancer resection or from craniofacial manipulation (iatrogenic)

Eyelid laxity is both a cosmetic and a functional problem.

Uncorrected, lower lid laxity may cause exposure keratopathy, epiphora, or problems with the lacrimal pump mechanism.

Lower eyelid laxity

Canthal dystopia

Poor eyelid snap back test: This test refers to evaluating the time for the eyelid to return to normal position after pulling the lower lid down and away from the globe. It is graded from 0 (brisk snap back) to IV (severe laxity).

Eyelid distraction—5 mm of eyelid distraction often considered excessively lax.

Dry eye including exposure keratopathy or punctate epithelial erosions

CT imaging of the face is appropriate in the evaluation of congenital craniofacial abnormalities. In the setting of orbital trauma, CT imaging is useful to assess for nasoorbital-ethmoid fractures.

In patients not bothered by the cosmetic defect, scheduled application of lubricant artificial tears may provide the necessary corneal protection to defer or prevent surgery in mild cases.

Careful attention must be made to prevent deprivation amblyopia by constant application of ointments, taping the eyelid shut, or patching of the eye.

If the cosmetic defect is bothersome or the patient is symptomatic, canthopexy, canthoplasty, or both may be performed to correct the eyelid abnormality.

Medial canthopexy in the absence of nasal fractures may be performed either with or without wiring as adapted from Mustarde³ and Callahan,⁴ respectively.