INTRODUCTION
Lateral canthoplasty is a procedure in which the lateral canthus is fixed (anchored)
to the lateral orbital rim after surgical division (lateral cantholysis). It is usually
performed with lower blepharoplasty in order to correct the laxity and malposition
of the lower lid [1]. Lateral canthoplasty also can control the position of the lower lid in order to
produce the desired shape of the eyelid fissure [2]. It is performed to change the eye slant [3] or lengthen the eyes [4] depending on the position of the fixation. In the West, the procedure is carried
out to uplift the downward slant of the eyelid, which is usually caused by aging [3]. However, Asians do not favor this because an upward slant makes the eyes seem smaller
and has a strong appearance. Therefore, cosmetic lateral canthoplasty is commonly
carried out in Asia. This procedure lengthens the palpebral fissure and lowers the
eye slant by moving the lateral canthus posterolaterally or posterolaterally downward.
This causes the lateral scleral triangle to increase in size, making the eyes appear
larger and leaving a smoother appearance.
Cosmetic lateral canthoplasty mostly includes lateral canthotomy and lateral cantholysis
[[4]
[5]
[6]
[7]]. However, this destroys the lateral canthal angle, and the scarring from this can
lead to a variety of deformities [8]
[9]
[10]
[11]. Therefore, the authors have designed and carried out a lateral canthoplasty which
preserves the canthal angle.
In this article, we introduce a method of lateral canthoplasty which preserves the
canthal angle, and discuss methods for preventing complications of cosmetic lateral
canthoplasty.
SURGERY RELATED ANATOMY
Lateral canthal tendon
The lateral canthal tendon (LCT) has a superficial component and a deep component.
The superficial component is a continuous extension from the orbicularis oculis muscle
that is inserted into the lateral orbital rim through the thickening of the overlay
whereas the deep component of the LCT diverges from the lateral end of the tarsus
and adjoins Whitnall's tubercle of the lateral orbital rim [1]
[12]. However, there is controversy surrounding the naming and the anatomical relationship
of the surrounding tissue [1]
[13]
[14]. The deep portion mainly serves to provide lateral canthal support; therefore, the
detachment and division of the deep portion is not recommended for ordinary cosmetic
lateral canthoplasty. Instead, the superficial component should be sufficiently detached
to allow the movement of the lateral canthus without tension.
METHODS
Preoperative evaluation
It is essential that the distance from the lateral canthus to the orbital rim and
the canthal tilt be checked before surgery ([Fig. 1]). If the goal of the surgery is the lengthening of the palpebral fissure, the lateral
canthus to orbital rim distance is important, and if the goal is change to the degree
of eye slant, the canthal tilt is important. In fact, however, there are many cases
in which the operation has both goals. Therefore, it is very important to conduct
a preoperative evaluation of both measurements when performing cosmetic lateral canthoplasty.
Fig. 1 Preoperative evaluation
(A) Lateral canthus to orbital rim distance. (B) Canthal tilt.
Operative technique
The surgical design is as shown in the picture ([Fig. 2A]). The design is composed of three incision lines, a lower eyelid incision, an upper
eyelid incision, as well as an incision for VY advancement. The lower incision line
is drawn 2 mm below the cilia, and the upper incision line is drawn following the
gray line directly below the cilia. The VY advancement incision is designed to allow
the elevation of the V-shaped flap from the grey line to the palpebral conjunctiva.
In some cases, the lower incision may be omitted, in which case surgical vision can
be ensured by further extending the upper incision towards the lateral canthus.
Fig. 2 Surgical design and surgical procedure diagram
(A) Surgical design. The tip of the V-shaped flap (X) and the tip of lateral canthus
(O) is indicated. (B) After the skin incision, detachment is carried out on the orbicularis
oculi muscle, the superficial canthal tendon, and the pre-periosteal tissue. (C) As
shown in the picture, after detachment, the lateral canthus, including the lateral
canthal angle, is able to move without tension. (D) The lateral canthus is affixed
at the appropriate position of the lateral orbital rim. (E) Defects of the upper eyelid
are sutured by VY advancement, and surgery is concluded with the suturing of the remaining
incision site.
Surgery is carried out under local anesthesia. After making a skin incision, a submuscular
dissection is conducted using Tenotomy Scissors and a bipolar coagulator ([Fig. 2B]). After this, the exposed superficial canthal tendon is sufficiently detached. The
pre-periosteal tissue should be appropriately detached, leaving a portion of tissue
at the orbital rim. After this, the lateral canthus is able to move without tension
as seen in the illustration ([Fig. 2C]). Next, the lateral canthus is fixed to the lateral orbital rim ([Fig. 2D]). Then, by precisely passing a needle through the tarsal plate of the lower eyelid
lateral end or through the canthal tendon attached to it, and by similarly passing
a needle through the periosteum and pre-periosteal tissue of the orbital rim, the
sutures are tied.
After being fixed, the eyelid shape should be checked while the patient's eyes are
open. At this time, the patient should be thoroughly observed for any signs of the
occurrence of ptosis or contact between the eyeball and lower eyelid. Once the fixation
is completed, the upper eyelid defect is sutured in a VY advancement manner, and closure
of the remaining skin incision site is performed ([Fig. 2E]).
RESULTS
Representative cases
Case 1
A female patient (26-year-old) presented with facial asymmetry and mild dystopia.
Bilateral lateral canthoplasty was performed. The right side was overcorrected more
than the left. Immediately after surgery, there was noticeable improvement of the
dystopia and the palpebral fissure had been lengthened. Five months after surgery,
good surgical results were still observed without any deformity of the external commissure
([Fig. 3]).
Fig. 3 Case 1
(A) Preoperative front view. (B) Immediate postoperative front view. (C) Postoperative
front view at 5 months.
Case 2
A 24-year-old female patient underwent bilateral lateral canthoplasty. Photos taken
one month and five months after surgery show a lengthening of the palpebral fissure
and a decrease in degree of the eye slant. Deformity of the external commissure was
not observed ([Fig. 4]).
Fig. 4 Case 2
(A) Preoperative front view. (B) Postoperative front view at 5 months.
DISCUSSION
Cosmetic lateral canthoplasty in order to lengthen the small palpebral fissure and
decrease the degree of the eye slant has become prevalent among East Asians. However,
as with conventional lateral canthoplasty, surgical methods that compromise the lateral
canthal angle may be accompanied by complications from the procedure. Common complications
include deformity of the external commissure, recurrence, mucosal exposure, and ectropion.
The first two complications may result in a reduction of the lateral white triangle,
in which case patients feel as if the surgery had no effect or even that their eyes
have gotten smaller [10]. Mucosal exposure and ectropion are aesthetically unpleasant and can cause eye dryness.
In this paper we discuss methods to reduce such complications.
Most lateral canthoplasty methods involve conducting lateral canthotomy in order to
carry out lateral cantholysis. However, the destruction of the canthal angle due to
lateral canthotomy can lead to various deformities, such as webbing or rounding of
the external commissure. Therefore, lateral canthoplasty methods have also been introduced
which preserve the canthal angle, in order to prevent such deformities [8]
[11]
[15]
[16]. On the other hand, it is difficult to use lateral canthoplasty methods that preserve
the canthal angle in cosmetic lateral canthoplasty. In cosmetic lateral canthoplasty,
unlike conventional lateral canthoplasty, mechanical ptosis can be avoided only by
separating the skin of the upper eyelid and lower eyelid because the direction of
the movement of the lateral canthus is posterolateral or posterolaterally downward.
In order to resolve this problem, the authors designed a method of conducting cantholysis
and lateral canthotomy that preserves the lateral canthal angle, and applied this
to cosmetic lateral canthoplasty. The biggest advantage of this method is that, by
preserving the lateral canthal angle, there is almost no occurrence of deformity of
the external commissure.
One disadvantage of this surgery is that a defect of the upper lid remains. However,
as this defect is on an area covered by the cilia, if the size of the V flap is not
designed to be big, it will nearly unnoticeable. In addition, if the suture layer
of the V flap does not match precisely, a trapdoor scar can appear. However, as this
can be fixed easily through cauterization or a simple excision, it could be considered
an insignificant complication compared to a deformity like webbing or rounding. The
authors are currently in the midst of collecting and analyzing patient data, and are
preparing to report the results.
Recurrence, mucosal exposure, and ectropion are mainly brought about by improper fixation.
The tissue that is fixed and the position of fixation are both important for the proper
fixation of the lateral canthus to the orbital rim. In order to reduce the cheese-wiring
effect, it is important that any fixed tissue include the tarsal plate at the lateral
canthus and the periosteum at the lateral orbital rim. However, as the size of the
tarsal plate near the lateral canthus becomes very small [17], it is not easy for the suture material to pass through this tissue, and depending
on the circumstances, the LCT connected to the tarsal plate can be used as a fixation
tissue instead. Because the thickness of the periosteum of the lateral orbital rim
is comparatively thin, leaving pre-periosteal tissue when performing detachment aids
in a secure fixation.
If the fixation position at the rim is too much towards the inner aspect of the lateral
orbital rim, entropion of the lower eyelid can occur, whereas if the position is too
much towards the lateral aspect of the lateral orbital rim, ectropion and mucosal
exposure are likely to occur. In addition, if the fixation position is excessively
downward, it appears unnatural and mechanical ptosis occurs. Keeping such things in
mind, it is possible to prevent unfavorable results and complications stemming from
improper fixation.
In conclusion, the following points should be kept in mind in order to reduce complications.
Before the operation, a precise evaluation of the preoperative anatomy of the patient's
eyelid should be carried out, and based on this, an appropriate surgical plan should
be formulated. In addition, surgical methods should ideally preserve the maximum normal
anatomy of the lateral canthus. The lateral canthus released during surgery should
be securely affixed to the proper area of the orbital rim. If surgery is carried out
taking these points into consideration, a suitable portion of the complications involved
in cosmetic lateral canthoplasty can be prevented.
