Abstract
BACKGROUND: Upper-eyelid hollowing can be treated with hyaluronic acid (HA) or poly-L-lactic acid (PLLA), which differ in onset and durability; objective comparative data are limited. OBJECTIVES: The aim of this study was to compare 9-month efficacy and safety of HA vs PLLA based on objective image-based metrics and patient-reported outcomes. METHODS: This single-center, prospective, nonrandomized cohort study enrolled patients who chose HA (single session) or PLLA (three sessions, 4 weeks apart) after standardized counseling.Three co-primary image-derived metrics-hollow area, mean curvature of the superior sulcus, and arc/chord ratio-were assessed at baseline and at 3, 6, and 9 months after the last treatment (T1-T3). Linear mixed-effects models estimated between-group differences(fixed: group, time, group × time, random: participantwith eye nested), with Holm adjustment for family-wise error.FACE-Q and Upper-Eyelid Hollowing Severity Scale (UEHSS) were secondary endpoints and safety used the full sample. RESULTS: Thirty-six participants (72 eyes) were enrolled, and 66 eyes completed follow-up. In the matched cohort (n = 48 eyes), at T1, HA outperformed PLLA across all co-primary metrics (Holm-adjusted P < .001). At T2, HA remained superior for hollow area and mean curvature (P < .01) with no difference in arc/chord ratio. By T3, PLLA showed greater improvement in all 3 metrics (P < .001). FACE-Q scores at T3 were comparable, whereas UEHSS slightly favored HA (odds ratio, 1.45; 95% CI, 1.02-2.06). Transient swelling and tenderness were more frequent with PLLA, whereas small lumps occurred only with HA, and no severe adverse events were observed. CONCLUSIONS: HA provides greater early improvement, whereas PLLA yields superior outcomes by 9 months, supporting pathway-based treatment selection.