Fan‐Dotting injection technique: A simple method for infraorbital rejuvenation using injectable Poly‐D,L‐lactic acid

Injectable fillers have been increasing in popularity for non-surgical lower eyelid rejuvenation in recent years.1 We proposed a simple and effective method using injectable poly-D,L-lactic acid (PDLLA; AestheFill; REGEN) recently in Journal of Cosmetic Dermatology.2 The injection method is superficial, wide, and even distribution of PDLLA under eyes using fanning technique.2 However, even distribution is difficult to achieve when performing traditional fanning technique especially for novice practitioners. Any uneven distribution of PDLLA may result in irregularity or nodules formation.3 In this article, we elaborate our modified method, “Fan-Dotting” injection technique, for even distribution of PDLLA over lower eyelids. The injection routines are as usual. For patients who have mild undereye defects, 5–6 ml of sterile water for injection (SWFI) and 1 ml of lidocaine are used for reconstitution a vial of injectable PDLLA. For patients who have moderate-to-severe undereye defects, 3–4 ml of SWFI and 1 ml of lidocaine are used.2 We choose a 1-cc syringe connecting with a 23G cannula as the injector. During injection, the whole cannula is inserted under the dermis from an entry point 1 cm lateral and inferior to the lateral canthus. The injection steps are as follows: inject a dot of PDLLA, pull the cannula slightly out, inject a dot of PDLLA, pull the cannula slightly out, …, until the desired region has been injected. Usually, the volume of a dot is around 0.020–0.033 ml, and the interval between 2 dots is 3–4 mm. This procedure is called as “Linear-Dotting Injection Technique.” (Figure 1) Then, repeat the Linear-Dotting method in different angles using the same entry point until the whole lower lid, and malar regions have been injected. Additional injections are made between 2 Linear-Dotting lines, or over the regions where the product is not enough (Figure 2). Care should be taken not to inject too much product near the entry point. For better understanding of Fan-Dotting technique, see Video S1. Fanning technique is a commonly used method when we want to distribute a product widely and evenly. However, the procedure is technically demanding. Practitioners must push the plunger steadily while pull out the syringe/cannula gradually at the same time. It is not easy to coordinate these two opposite-direction motions. If uneven distribution of the product happens, it may result in post-injection irregularity or nodules formation especially over thin skin regions. To solve these problems, we divide the motions into two parts, “inject, then pull,” and repeat them, as Fan-Dotting method. This procedure is technically easier than Fanning method. For fat graft implantation, usually we need an injection gun because a fat parcel must be small enough (<0.01 ml) to prevent it from central necrosis.4 However, there is no central necrosis problem of PDLLA. Therefore, there is no volume amount limit of each dot. According to our experience, we can distribute PDLLA evenly by 0.020–0.033 ml per dot. Because a 1-cc syringe has the smallest calibration scale of 0.02 ml, this volume can be controlled using a 1-cc syringe by hands. By mathematical calculation, the diameter of a microsphere with 0.020–0.033 ml is 3.4–4 mm. Accordingly, the interval between two dots should be at least 3–4 mm. Due to the cohesivity of PDLLA is low,5 the shape of a dot will become flat by skin compression after injection, and its diameter will become larger. It will cause some product overlap between two dots. Due to these properties, it is easy for us to achieve even distribution of PDLLA using Fan-Dotting injection technique. However, there is no comparative study with other techniques. Further studies should be made to include an objective validation of Fan-Dotting technique and compare with other techniques. In conclusion, PDLLA can be effectively used for lower eyelid rejuvenation. However, the traditional Fanning injection method is technically challenging especially for novice practitioners. We propose a modified method, “Fan-Dotting” injection technique, as a simple and easy method for lower eyelid rejuvenation using PDLLA. The authors specially thank Ella Yi-Hsin Yen for her kindly assistance for the video clip editing and Tung-Hsuan Lin for her kind assistance with the artwork. Dr. Lin J-Y and Dr. Lin C-Y are medical consultants of Jiangsu Wuzhong Aesthetic Biotech and medical directors of REGEN Biotech. The authors confirm that the ethical policies of the journal, as noted on the journal's author guidelines page, have been adhered to. No ethical approval was required as this is a review article with no original research data. Patients provided written consent for the use of their images. Video S1 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.