A canthoplasty is a surgical procedure whereby the terminal portion of the lower lid is secured to the bone of the outer orbit.  In essence THE LID IS TIGHTENED.In reconstructive surgery the tarsus (the cartilage skeleton of the eyelids) is typically trimmed and sutured to the periosteum (tissue lining the bone).  In cosmetic surgery less disruptive techniques have been developed so that distortion of the canthal angle (angle where the eyelids meet) is not distorted.  A canthoplasty, or its more simplistic cousin (the canthopexy) is often performed in cosmetic lower lid surgery (blepharoplasty) to help maintain the normal position and shape of the lower lid.  Poor canthoplasty surgery is one of the most difficult eyelid problems to correct.  This is a topic of a different discussion which I will review in a later blog.

Before getting into the canthoplasty procedure itself it is important to understand canthal terminology and anatomy.

  1. The lateral canthal angle is the angle formed where the outer part of lids meet.  It is typically almond shaped and slightly higher than it matching angle where the lids meet medially (near the nose)
  2. The lateral commissure is the point where the lids meet (the apex of the angle)
  3. The lateral canthal tendon or lateral palpebral ligament (interchangeable terms) is the band of tissue which connects the lids to bone.  This is one of the structures which is tightened and/or shortened when a canthal suspension is performed.

When the canthus is manipulated surgically the canthal angle and lateral commissure may or may not be incised, but the tendon is always cut, shortened or tightened.

Below is axial cut (view from above) through the eye, eye muscles and bone around the eye (orbit) demonstrating the lateral canthal tendon.  The drawing is from my new textbook “Master Techniques in Blepharoplasty and Periorobtal Rejuvenation”which will be in press by October 2011. The tendon has an anterior reflection and attachment (AT), a posterior reflection and attachment (PT) and a point of attachment to bone (A).  The important landmarks are the(PT) which by its location assures the lid hugs the eye before attaching to bone.   The point of attachment (A) is at a bone outgrowth called Whitnall’s tubercle.  As you can see it is behind the tip of the bone which directs the lid to hug the eye (as we discussed) so that the lid and eye are always in contact.  If this attachment was more anterior (forward) there would be a space between the lid and the eye (which occurs in certain eyelid problems or after previous complicated surgery with complications)

VERY IMPOTANT POINT.  When performing canthoplasty correctly it is critical to recreate the normal lid attachments to bone (as described above).  If this is not performed correctly problems in lid shape and position can occur.  Make sure an eyelid specialist performs this procedure to avoid such problems.