Correspondence on: “Efficacy of high-intensity focused ultrasound for treating upper and lower eyelid sagging”

Dear Sir,

We read with considerable interest the prospective cohort study by Hwang et al.¹ evaluating high-intensity focused ultrasound (HIFU) for upper and lower eyelid laxity. The authors report a statistically significant reduction in average lid length (ALL) of 0.94 mm at 12 weeks, accompanied by favorable clinician- and patient-reported outcomes. In an era marked by increasing demand for minimally invasive periocular rejuvenation, this investigation addresses an area of genuine clinical importance.

The study is commendable for attempting objective quantification in a field often dominated by subjective aesthetic scales. The incorporation of measurable ALL reduction represents a meaningful step toward standardizing outcome assessment in energy-based periocular interventions. Furthermore, the authors’ detailed safety protocol—including corneal shielding and use of a 2.0-mm probe—demonstrates thoughtful procedural design in a region where anatomical precision is paramount.

Nevertheless, several considerations merit further elaboration to contextualize the findings within the broader literature.

First, while statistical significance was achieved, the clinical magnitude of a 0.94 mm reduction in ALL requires careful interpretation. In rater-blinded prospective evaluations of micro focused ultrasound for facial and cervical tightening, improvements have been characterized as modest yet perceptible.² Without a control or sham-treated comparator, however, it remains challenging to distinguish true tissue contraction from photographic variability, transient oedema, or subtle brow recruitment. Inclusion of a randomized or split-face design in future studies would greatly enhance causal inference and strengthen the evidentiary framework.

Second, although the mechanistic basis of HIFU is well established, periocular extrapolation deserves scrutiny. Histologic validation of selective thermal coagulation zones within the superficial musculoaponeurotic system (SMAS) demonstrated controlled collagen contraction without epidermal disruption, thereby providing foundational biological plausibility.³ Yet eyelid tissue differs fundamentally from midfacial and cervical structures in thickness, adnexal density, and proximity to the globe. Dedicated periocular imaging—such as high-frequency ultrasound or optical coherence tomography—could further substantiate targeted tissue effects and reinforce long-term safety claims.

Third, systematic evaluation of HIFU across facial regions confirms overall safety and statistically significant tightening outcomes.⁴ However, pooled analyses also highlight heterogeneity in treatment parameters, outcome metrics, and follow-up intervals. The present study contributes valuable eyelid-specific data, but incorporation of validated global scales such as the Global Aesthetic Improvement Scale (GAIS), together with three-dimensional stereophotogrammetry, would facilitate inter-study comparability and enhance reproducibility.

The exclusive inclusion of Korean women with Fitzpatrick skin types III–IV, while appropriate for internal consistency, limits external generalizability. Ethnic and structural variations in dermal thickness, orbital anatomy, and collagen architecture may influence response profiles. Multicenter investigations incorporating broader demographic representation would strengthen translational applicability.

Importantly, prior ultrasound studies in the periocular region have predominantly focused on brow elevation or wrinkle attenuation rather than direct eyelid laxity measurement.⁵ By specifically targeting upper and lower eyelid tissue and providing quantitative data, Hwang et al. advance the literature beyond surface-level wrinkle analysis. This distinction is clinically meaningful, as eyelid laxity represents a distinct structural entity from periorbital rhytides.

In summary, this study offers encouraging preliminary evidence that HIFU may provide measurable tightening in selected patients with mild-to-moderate eyelid laxity, with a favorable short-term safety profile. The work represents a constructive step toward defining the role of energy-based devices as adjuncts—or in carefully selected cases, alternatives—to surgical blepharoplasty. Future randomized controlled trials with extended follow-up, standardized outcome metrics, and objective imaging correlation will be instrumental in clarifying durability, magnitude of effect, and optimal patient selection.

We congratulate the authors for contributing rigorously collected periocular data to an evolving field and for stimulating further investigation into non-invasive eyelid rejuvenation strategies.

Ethical approval

None.

Declaration of competing interest

None declared.