Periorbital Structural and Functional Modulation Following Liquid-Type Polycaprolactone Treatment: A Pilot Study

Background: Periorbital aging involves complex structural and functional changes, including decreased eyelid opening and alterations in infraorbital contour. Conventional collagen biostimulators mainly focus on localized volume augmentation and dermal remodeling, with limited considerations for broader tissue interactions within the periorbital region. Objective: To evaluate structural and functional changes following treatment with a liquid-type polycaprolactone (PCL)-based collagen biostimulator. Methods: Three patients were analyzed. Clinical photographs were obtained at baseline, 1 month, and 3 months. Measurements were normalized to iris diameter. Eyelid-related and infraorbital contour parameters, along with canthal tilt angle (CTA), were assessed under neutral gaze and maximal effort. The treatment was performed via upper (forehead) and lower (infraorbital) approaches without direct injection into the upper eyelid. Results: Margin reflex distance 1 (MRD1) showed an overall increasing trend in both neutral gaze and maximal effort conditions, while ΔMRD1 remained relatively unchanged. Medial canthus-to-brow vertical distance (CBVD-M) showed a tendency to increase, whereas brow-to-lid distance (BLD) and lateral CBVD (CBVD-L) did not demonstrate consistent patterns. CTA increased across cases. Upper concavity height (UC), peak protrusion height (PP) and lower concavity height (LC) decreased concurrently. Conclusions: Liquid-type PCL-based treatment was associated with functional and structural changes in the periorbital region. Improved eyelid opening without direct upper eyelid injection may suggest indirect regional effects through contiguous anatomical planes. Changes in lower eyelid contour parameters support broader structural and functional changes.