Quantifiable Improvement in True Downslanting Palpebral Fissure Morphology Following Upper Blepharoplasty: Analysis of Canthal Position and Fissure Inclination

Aim: The objective of this study was to investigate and characterize the phenotypic features of Asian individuals with true downslanting palpebral fissure, analyze the specific anatomic characteristics of their ocular structures, make an attempt to quantify and redefine this type of eye shape, and explore the role of eyelid plastic surgery in correcting this condition and ameliorating the “sad-appearing” facial aesthetic. Methods: An investigation was conducted to characterize the phenotypic features and quantify the structural parameters of patients presenting with the clinical condition referred to as “sad eyes” (defined as a downward-slanting palpebral fissure associated with a melancholic facial appearance). The procedure of upper blepharoplasty was performed through incision. Objective measurements were obtained preoperatively and postoperatively to quantify the following parameters: vertical height difference between the medial and lateral (DH), the acclivity of the palpebral fissure (AX), and the angles between the medial and lateral canthus and the vertical midline (AMV and ALV), respectively. Differences in DH, AX, AMV, and ALV between the preoperative and postoperative groups were analyzed using a paired t test. Results: Asians patients with “sad eyes” exhibited a preoperative DH ≤ 2 mm, AX ＜ 10 degrees, and a downward-slanting contour of the lateral lower eyelid. Postoperatively, all patients exhibited a significant increase in DH, AX, AMV, and ALV compared with preoperative values (all P < 0.05). For the subgroup of “sad eyes” patients diagnosed with concurrent medial epicanthus, a comparative analysis of preoperative and postoperative parameters showed that DH, AX, AMV, and ALV also exhibited a significant postoperative increase (all P < 0.05). Conclusions: In the domain of eyelid plastic surgery, lateral tissue release combined with upper blepharoplasty (via transcutaneous incision) is an effective intervention for patients with “sad eyes”—characterized by preoperative DH ≤ 2 mm, AX ＜ 10 degrees, and a downward-sloping lateral lower eyelid contour. This surgical approach not only significantly increases key structural parameters (DH, AX, AMV, and ALV; all P < 0.05) to correct the downward-slanting palpebral fissure but also alleviates soft tissue tension, restores the eyelid’s natural curvature, and enhances its aesthetic vitality. Notably, the procedure yields consistent therapeutic effects even in the subgroup of patients with concurrent medial epicanthus, further substantiating the scientific validity and clinical efficacy of this surgical technique. Beyond aesthetic improvement, the correction of the “sad-appearing” facial phenotype concomitantly boosts patients’ psychological confidence and willingness to engage in social interactions. Collectively, these findings support the clinical application of lateral tissue release as a reliable, patient-centered strategy for addressing “sad eyes” and optimizing both functional and aesthetic outcomes of eyelid plastic surgery.