Comparison of asymmetric Z‐plasty and Stallard Z‐plasty in correction of epicanthus

To investigate the clinical effect of asymmetric Z‐plasty with central axis inward displacement and stallard Z‐plasty in the correction of epicanthus.


| INTRODUC TI ON
Epicanthus is a flap-skin that covers the inner canthus epicanthus, and it can cover the lacrimal caruncle of the inner canthus, making the eyes appear less bright and lacking in aesthetic appeal, with a higher incidence in Asian populations. 1 Based on the characteristic of epicanthus formation in oriental, various skin flaps are applied to correct the epicanthus, open the canthus, and increase the palpebral fissure, to achieving the effect of improving the appearance of the eyelids.It has become one of the important cosmetic surgeries for eyelid plastic surgery in Asian people. 2 At present, there are many surgical methods for correction, with the most classic surgical methods being "Z" plasty, "V-Y" plasty, "L" shaped skin excision, Mustarde's ectropion correction, etc.
However, each method has its own advantages and disadvantages, and there is no universally recognized best method. 3,6The most common postoperative complications are obvious scars, bilateral asymmetry, and insufficient correction, 2 with scar formation being the main reason for poor postoperative results. 4Since 2009, the author has been using the asymmetric Z-plasty with central axis inward displacement method to correct epicanthus and achieved good results.To objectively evaluate the effects of the two methods of epicanthal plasty, we retrospectively compared the cases of this method and the classic stallard Z-plasty by the author.

| Preoperative design
Group A patients were treated with asymmetric Z-plasty with central axis inward displacement, the incision design is shown in Figure 1: This forms the asymmetric Z-plasty incision, with the line CB as the central axis, CA as the upper arm and BD as the lower arm of the "Z".Group B patients were treated with classic stallard Z-plasty, the incision design is shown in Figure 2: Firstly, set a new inner canthus point A, which represents the projection point of the innermost end of the inner canthus angle on the skin.The starting point of upper eyelid epicanthus is B, the ending point of the free edge of lower eyelid epicanthus is C, and pull the epicanthus to the nasal side to fully expose the inner canthus, Point D corresponds to point A, so that the length of AB line is equal to the length of DC line, that is, two dual triangular flaps are formed on the outside of ABC and the inside of DCB.

| Evaluating indicators
Postoperative photographs will be taken to observe wound healing after 7 days.At 6 months post-surgery, photographs will be taken to assess scar concealment and the recurrence of inner canthal redundant skin.

| Statistical analysis
All statistical analyses were performed using SPSS22.0statistical software, Independent sample t-tests and Mann-Whitney U tests were used for intergroup comparisons.Chi-square tests were used for compare the enumeration between groups.p-Values <0.05 were considered statistically significant.

| Wound healing
In group A and group B, the incision of epicanthal plasty patients healed at grade A 7 days after operation, without infection or poor wound healing.

| Postoperative scar concealment
In Group A, 81 cases had completely hidden scars, 44 cases had partially hidden scars, and zero cases had visible scars.In Group B, zero cases had completely hidden scars, 21 cases had partially hidden scars, and 47 cases had visible scars.The comparison between the two groups showed a statistically significant difference (p < 0.05) (Table 1).For patients with mild scar hyperplasia, corresponding anti-scar treatments such as beauty skin care

| Recurrence
In Group A, 122 cases had no retraction of epicanthus, three cases had mild retraction, and zero case had complete retraction.In Group B, 63 cases were persistent, five cases had mild retraction and zero case had obvious retraction.There was no significant difference between group A and B (p > 0.05).(Table 2).

| DISCUSS ION
Epicanthus is semi-moon shaped web fold that is slanted or vertically distributed in front of the inner canthus.Based on the orientation and direction, it can be divided into upper eyelid shape, inner canthus shape and lower eyelid shape. 6According to Wang  3).
Since 2000, We began to learn how to use the classic stallard Zplasty to correct epicanthus.By 2009, We had mastered it skillfully, and because the author had used asymmetric Z-plasty with central axis inward displacement after 2009, there was no case of using stallard Z-plasty.In this study, the author's operation case in 2019 was selected as group A, which also considered that the author had used asymmetric Z-plasty with central axis inward displacement method for 10 years and could use it skillfully.The results showed that there was no significant difference in wound healing between group A and B 7 days after operation, and there was no infection or poor wound healing.The difference of scar hidden between group A and group B was statistically significant.The incision scar of group A was more concealment than that of group B, but the difference of retraction was not statistically significant.Therefore, compared with stallard Z-plasty, the asymmetric Z-plasty that we have devised incorporates a pivotal advancement, wherein the central axis of the "Z" is repositioned towards the inner aspect of the epicanthus.This departure from the traditional practice of utilizing the epicanthus margin as the central axis marks a significant innovation, meanwhile the incision scars of asymmetric Z-plasty are concealed more effectively.

| CON CLUS ION
In a word, the understanding of the anatomical causes of epicanthus gradually tends to be consistent.The key principle for different types of epicanthus is to correct epicanthus while minimizing scarring and concealing it.Based on this principle, we designed asymmetric Zplasty with central axis inward displacement, which has achieved good surgical results in clinic.However, each surgical method has its The epicanthus margin as the central axis.
Eye Shape Adjustment Easily forming fan-shaped double eyelids.Easily forming parallel-shaped double eyelids.

Strengths
Retaining the advantages of Z-plasty for axis elongation by relieving tension while avoiding the drawback of external scarring on the nasal side.
Easy to understand and design.
Limitations Beginner find it challenging to comprehend.Nasal side scar.

A
total of 338 patients who underwent epicanthal plasty in the Department of Plastic Laser Cosmetology of Hunan Provincial People's Hospital from 2009 to 2019 were retrospectively analyzed, including 238 patients of epicanthus were treated with asymmetric Z-plasty with central axis inward displacement in 2019 and 100 patients with classic stallard Z-plasty in 2009.The patients who underwent asymmetric Z-plasty with central axis inward displacement were defifined as group A, and those who underwent classic stallard Z-plasty were defifined as group B. Acrroding to the inclusion and exclusion criteria, 125 patients in group A and 68 patients in group B were finally included in this study.Group A comprised 125 patients, including eight males and 117 females, with an average age of 26.73 ± 5.28.Referring to Wang 5 for grading of epicanthal folds, there were 95 cases of mild epicanthus, 20 cases of moderate epicanthus, and 10 cases of severe epicanthus.Group B comprised 68 patients, including four males and 64 females, with an average age of 26.46 ± 5.10, there were 33 cases of mild epicanthus, 27 cases of moderate epicanthus, and eight cases of severe epicanthus.There was no significant difference in age and grading of epicanthal folds between groups A and B (p > 0.05).
photos taken at the time of suture removal 7 days after surgery and at 6 months postoperatively.Exclusion criteria: (1) Patients who cannot follow-up for more than 6 months after operation; (2) Patients who have received other cosmetic treatments such as entocanthion injection after operation; (3) Patients who have other systemic or local diseases after operation, affected the entocanthion morphology; (4) patients with failed epicanthal plasty; (5) patients with scar constitution.

First
, confirm the new medial canthus point A, which represents the innermost projection of the inner canthus angle on the surface skin.Pull the redundant skin towards the nose side to fully expose the inner canthus, and mark point B corresponding to point A. The point C is where the upper eyelid crease intersects with the inner canthal fold.Point D is located 1 mm from the lower eyelid margin.Next, connect points CA and CB along the curved upper eyelid line, and connect points BD 1 mm from the lower eyelid margin.Ensure that CA, CB, AB, and BD are equidistant.Two lines are formed, from point C to point A and from point C to point B. A line from points B to D is spaced 1 mm closer to the palpebral edge of the lower eyelid.

2
Group A: After routine disinfection, 2% lidocaine and 1:100 000 unit adrenephrine fluid were used for local infiltration anesthesia.After the local anesthesia took effect, a No. 11 scalpel blade was used to sequentially incise the BD, BC, and AC along the marked line.Then, surgical scissors were used to fully separate the subcutaneous layer in the medial canthal area, cut the adhesions between the skin and muscle layer, and remove the white fibrous adhesion tissue on the surface of the medial canthal muscle layer.After sufficient separation, the BD skin incision split open, and the ACB flap naturally retracted to the BD skin incision area.The medial canthus point B was basically located at the new medial canthus point A, and a slight "cat ear" was trimmed on the outer side of the ABC flap as needed during the procedure.The B and A points were sutured with 7-0 nylon thread, and suture each incision with skin tension-free alignment sutures.If double-eyelid blepharoplasty is performed simultaneously, the double eyelid line is connected to line CA immediately after surgery, as shown in Figure 3(A).The surgical operation is shown in Supplemental Video File.Group B: After routine disinfection, 2% lidocaine and 1:100000 unit adrenephrine fluid were used for local infiltration anesthesia.After the local anesthesia took effect, a No. 11 scalpel blade cut along the design line to form two triangular flaps on the outside and inside respectively.Then, the subcutaneous layer of the inner F I G U R E 1 Asymmetric Z-plasty.(A) Design of the skin incision.(Upper) Canthus pulled position.(Middle) Natural position.(Underneath) Immediately postoperative; (B) Preoperative design.Stallard Z-plasty.(A)Design of the skin incision;(B) Preoperative design.canthus angle area was fully separated with surgical scissors, and the adhesion between the skin and the muscle layer was cut off, so that the skin naturally retracted and the inner canthus ligament was exposed.The skin was sutured with 7-0 nylon thread immediately after surgery, as shown in Figure 3(B).Apply a dressing for 2 days after operation, with cold compresses for the first 2 days.Remove the dressing after 2 days and clean with saline solution before applying chlortetracycline eye ointment twice daily.Remove the medial canthal area sutures after 7 days postoperatively.

1 .
Scar concealment: a. Well concealed: Scars are located within the inner canthus and are not prominently visible.b.Partially concealed: Some scars are exposed outside the inner canthus.c.Not concealed: Scars are entirely exposed outside the inner canthus and are visibly noticeable.2. Recurrence of epicanthus: a.No retraction: The lacrimal caruncle is completely exposed, and there is no retraction of epicanthus.b.Mild retraction: the epicanthus retracts less than 1/3 of the preoperative extent.c.Obvious retraction: the epicanthus retracts equal to or more than 1/3 of the preoperative extent.

1
and external patches were given to gradually fade and improve the scars.Through the comparison between the two groups, the author thinks that the incision of inner canthus in group A is more hidden, and has the advantage of scar concealment compared with group B. Typical results from these cases are shown in Figure 4. F I G U R E 3 (A) Immediately after asymmetric Z-plasty; (B) Immediately after stallard stallard Z-plasty.Comparison of postoperative scar concealment between group A and group B.

2
,5 the severity of epicanthal folds can be classified as follows based on the degree of epicanthus covering lacrimal caruncle: (1) Mild, where the epicanthus covers less than half of the lacrimal caruncle and width is less than 2 mm; (2) Moderate, where the epicanthus covers more than half of the lacrimal caruncle but not all of it, and width is 2-4 mm; (3) Severe, where the lacrimal caruncle is completely covered and the epicanthus width is more than 4 mm.Most epicanthus were congenital, and a few were caused by postnatal causes such as trauma and burn.It is reported that the incidence of epicanthus is 74.9% in China, especially in northern China, which is as high as 90.7%.2At present, it is generally accepted that the formation mechanism of congenital epicanthus is caused by the abnormal attachment of anterior branch of medial canthus ligament and the action of orbicularis oculi muscle with orbital anterior dislocation on the thin skin.7 The epicanthus covers the lacrimal caruncle of the inner canthus, which shortens the appearance of the palpebral fissure and widens the distance between the inner canthus.Even the most perfect double eyelid plasty will be inferior because the epicanthus is not well treated.With the development of the cause, classification and anatomy of epicanthus, its correction methods have also experienced an evolutionary process, from simple skin resection to advancement method and skin-flap method,8 but the key points are in two aspects, one is to release the adhesion between ectopic orbicularis oculi muscle and connective tissue, so as to relieve the abnormal traction force.On the other hand, the extension Vertical line increases vertical skin.Zplasty is one of the most widely used methods in epicanthoplasty.In Stallard's design, the epicanthus margin was used as the central axis, with both arms being of equal length, forming two symmetrical triangular flaps.Therefore, it is known as the Stallard Z-plasty.Its typical feature is that the epicanthus margin serves as the central axis.Due to the flexibility in designing the lengths and angles of the two arms, various modified Z-plasty techniques have emerged in clinic.WangH9 thinks that although Z-plasty and improved Z-plasty are different in design details, the basic principle is to exchange positions through the cross between adjacent flaps, to solve the problem of skin shortage in a certain axis direction, so as to reduce the skin tension at the incision and reduce the degree of scar.In stallard Z-plasty, the vertical axis of the epicanthus was extended and the defect of the vertical skin was eliminated.The epicanthus was well corrected.Therefore, the stallard Z-plasty has become a classic method for epicanthus correction and has been widely used.The author has used this method for many years, but the design feature of the Z-plasty is that the epicanthus edge is the central axis, the two flaps cross each other and the incision will cross the epicanthus edge.After suturing, F I G U R E 4 Asymmetric Z-plasty.(A) Preoperative, (B) Six months after operation.Stallard Z-plasty, (c) Preoperative (d) Six months after operation.Comparison of epicanthus retraction between group A and group B. incision was formed on the nasal side of the inner canthus, and a more obvious scar was formed after healing.In order to reduce the obvious incision scar, we designed Z-plasty as asymmetric Z-plasty with central axis inward displacement.The innovative asymmetric Z-plasty we have designed involves a key innovation where the central axis of the "Z" is moved towards the interior of the epicanthus, breaking away from the conventional constraint of using the epicanthus margin as the central axis.In order to avoid scar formation on the nasal skin surface of the inner canthus, we changed the design of the classic Stallard Z-plasty method with the epicanthus edge as the central axis to the epicanthus edge as the central axis, which starts from the double eyelids line and ends at the innermost end of the inner canthus angle.In addition, the Z-shaped upper arm is designed to follow the double eyelids line, which ensure the smooth, natural double eyelids line and the inner canthus angle.The lower arm is close to the lower palpebral edge, which can hide the early incision scar.Although the medial flap was transposed to the lower palpebral edge, part of the incision was outside, because the tension of the lower eyelid incision had been completely relieved.Even if there were some incision scars in the early stage, they would subside in the later stage.Its primary advantage lies in retaining the advantages of Z-plasty for axis elongation by relieving tension while avoiding the drawback of external scarring on the nasal side.(Table advantages and limitations.It should be analyzed comprehensively according to the aesthetic demands of the patient's actual situation, which varies from person to person.TA B L E 3 Comparison of the key steps of the two technologies.Asymmetric Z-plasty with central axis inward displacement Stallard Z-plasty Preoperative design The new inner canthus point A is the projection point on the surface skin of the innermost point B of the inner canthus.Point C is the intersection of the upper eyelid crease arc line and the inner canthal fold.Point D is located 1 mm below the eyelid margin.Then, connect CA and CB along the upper eyelid crease arc line, and connect BD 1 mm below the lower eyelid margin.CA, CB, and BD are equidistant.The point A is the inner projection point on the surface skin of the innermost point of the inner canthus.Point B is the starting point of the upper eyelid epicanthus, and point C is the endpoint of the lower eyelid epicanthus.The excess skin is pulled towards the nose side to fully expose the inner canthus, point D corresponding to point A, AB=DC, thus forming two symmetric triangular skin flaps, one on the outside (ABC) and one on the inside (DCB).Design schematic Differences in the central axis The central axis starts at the upper eyelid line and ends at the innermost corner of the medial canthus.