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Lateral canthoplasty: A core procedure to treat lower eyelid conditions
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The appearance of the eyelids is one of the primary factors of human facial beauty. Going past the cosmesis, eyelids have a functional role and, as such, indirectly become an integral part of the underlying globe. They act like curtains to the globe, protecting it. In addition, they play a significant role in the overall health of the ocular surface and are responsible for spreading the tear film from the lower eyelid tear meniscus to the entire ocular surface, hence contributing to optimal vision. Any compromise to the normal function and anatomic resting position of the eyelids can have a deleterious effect on overall facial cosmesis and potentially cause tissue degradation, including corneal epithelial breakdown, corneal melt and perforation.
Lateral canthoplasty may be considered as one of the most valuable oculoplastic surgical procedures to correct lid abnormalities. The indications include ectropion, entropion, lateral canthal dystopia, horizontal lid laxity, lid margin eversion, lid retraction with or without soft tissue deficiency, paralytic lagophthalmos and aesthetic improvement. This procedure is a valuable adjunct to lower blepharoplasty, in the delivery of orbital tumors and in the prevention of some of the above-mentioned entities.
In this column, Swapna Vemuri, MD, and Jeremiah Tao, MD, FACS, describe their technique for lateral canthoplasty.
Thomas “TJ” John, MD
OSN Surgical Maneuvers Editor
Lateral canthoplasty is a core oculoplastic procedure that treats an array of lower eyelid malposition conditions such as ectropion and retraction. The eyelid tightening effect also makes canthoplasty an important adjunct in many cosmetic lower eyelid procedures.
In brief, the lateral canthal angle is deconstructed, and the lateral eyelid is re-anchored to the periosteum of the lateral orbital rim. Whether a part of a cosmetic or a functional procedure, a secure and well-positioned lateral canthus allows the eyelids to look and function normally.
An understanding of the indications and limitations is important in lateral canthoplasty. A thorough preoperative clinical assessment delineates the vectors acting on the lower eyelid.
The lid distraction and snap-back tests assess lower eyelid laxity (Figure 1). When these findings are present, horizontal eyelid shortening and re-anchoring may be beneficial; however, there are cases in which these techniques alone would be inadequate. The first is in the presence of a “negative vector,” as seen with globe prominence, in which simply tightening the lower eyelid would worsen lower eyelid retraction due to a tendency for the lid to slip below the globe (Figure 2). A second is a patient with midface ptosis or cicatricial (scar) disease in whom vertical vectors will likely overcome the single lateral suture anchoring. A “two-finger test” is useful to identify these problematic scenarios. In this test, one finger simulates lateral canthal fixation. If a second finger is necessary to further correct malposition of the central lid (Figure 3), then lateral canthoplasty alone may be insufficient. Additional procedures may include implants, spacer grafts, midface advancement or a combination of these, which is beyond the scope of this article. Lastly, it is critical to evaluate for facial nerve paresis because these patients often need additional procedures to treat eyelid malposition.
Figure 1. Lid distraction test (a). Snap-back test (b).
Figure 2. If only a lateral canthoplasty and canthopexy are performed in an individual with a prominent globe, the lid slips under the globe.
Images: Vemuri S, Tao J
Figure 3. The two-finger test in which one finger simulates lateral canthal fixation (a) and the second elevates the central lower eyelid (b), indicating the need for additional vertical eyelid support.
Figure 4. A No. 15 blade is used to make a horizontal lateral canthotomy skin incision (a). Straight scissors complete the lateral canthotomy (b). An inferior cantholysis is performed (c).
Surgical technique
A No. 15 blade is used to make a horizontal lateral canthotomy skin incision (Figures 4a to 4c). Straight scissors complete the incision. The scissors are then turned inferomedially to locate and sever the inferior crus of the lateral canthal tendon. An adequate cantholysis is confirmed when the lateral lid distracts freely away from the globe, also known as a “swinging eyelid” (Figure 5). The amount of redundant eyelid is determined, and the lid is resected or a tarsal strip procedure is performed in which the anterior lamella, mucocutaneous junction and posterior conjunctival epithelium are dissected off of the tarsus. If there is a significant disparity in length of the upper and lower eyelids, a similar tarsal strip can be performed on the upper eyelid. A 4-0 polyethylene or polyglactin suture is then passed through the tarsus. If both the upper and lower lids are shortened, the same suture can then be passed through the upper lid tarsal strip (Figure 6a). The 4-0 suture then anchors the lid(s) to the inner rim of the lateral orbital wall to achieve appropriate globe apposition (Figure 6b).
Figure 5. Swinging eyelid demonstrating a complete inferior cantholysis.
Figure 6. A 4-0 Mersilene suture is passed through the tarsus (a). The lid is anchored to the inner rim of the lateral orbital wall in order to achieve appropriate globe apposition (b).
Figure 7. The lateral canthal angle placed too high on the right side.
Anchoring the eyelid too anteriorly may result in tenting of the lid away from the globe, although in individuals with a prominent eye, a slightly more anterior anchoring point on the lateral orbital rim may be necessary to forestall slippage of the lid toward the inferior equator. The lateral canthal angle should be at or above the mid-pupil and usually slightly above the level of the medial canthal angle (Figure 7). After the lower eyelid is secured, an interrupted 6-0 plain gut suture can be passed to align the gray lines of the lower and upper eyelids. The lateral skin incision can be approximated with interrupted 6-0 plain gut sutures.
Lateral canthoplasty is an important tool in both cosmetic and functional eyelid surgery. It is simple and fast. It treats eyelid malposition and can restore normal tone; however, it is critical to recognize the cases in which canthoplasty alone may be inadequate. Remember that patients with prominent eyes, midface ptosis or facial nerve paresis may need additional procedures to support the eyelid.