Three-dimensional Stereoscopic Evaluation and Quantitative Gray Scale Assessment of the Nasolabial Fold and Its Application in Injection Therapy

Abstract

With the growing demand for aesthetic enhancements, particularly filler injections for nasolabial folds (NLFs), there is a need for more objective and quantitative assessment methods beyond the traditional subjective scales like the Wrinkle Severity Rating Scale (WSRS). This study introduces a novel evaluation method combining 3-dimensional (3D) imaging and grayscale analysis to objectively assess NLF severity and treatment outcomes. A total of 100 healthy participants (86 females, 14 males; mean age 41.85±11.53 years) were assessed using WSRS scores and quantitative 3D measurements. The results demonstrated a significant positive correlation between WSRS scores and gray values (r=0.985, P < 0.05). Significant differences in gray values and 3D linear measurements were observed across WSRS score groups, with high intra-rater reliability confirmed by intraclass correlation coefficients. In addition, 54 patients (mean age 42.9±8.9 y) with moderate to severe NLFs received hyaluronic acid injections. One month post-treatment, WSRS scores significantly decreased (from 3.74±0.45 to 1.63±0.59, P < 0.05), and significant improvements were observed in several 3D measurements. The average gray value also decreased significantly (P < 0.05), indicating a reduction in wrinkle depth. These findings were supported by representative photos showing patient satisfaction and no severe complications. This study validates the use of 3D imaging and grayscale analysis as reliable tools for objectively assessing NLF severity and monitoring treatment efficacy, potentially improving the precision and reliability of aesthetic evaluations in clinical practice.