Facial vascular embolism following hyaluronic acid injection is a rare but potentially serious complication that may lead to tissue ischemia, necrosis, and scarring. Early assessment of local tissue perfusion is important for evaluating treatment response and predicting clinical outcomes.

This retrospective observational study aims to evaluate whether indocyanine green angiography (ICGA) can provide objective, real-time information on tissue perfusion in patients with facial vascular embolism after hyaluronic acid injection. The study will review existing medical records, ICGA imaging data, and follow-up information from patients treated at a single center. The main question is whether ICGA findings before and after initial rescue therapy can help assess early perfusion recovery and identify patients who may require additional intervention or develop persistent tissue damage.

This is a single-center, retrospective, observational study. The study will use existing clinical data generated during prior routine care, including medical records, ICGA imaging data, and follow-up documentation. No additional examinations, treatments, or study-specific follow-up visits will be introduced.

The study focuses on patients with facial vascular embolism following hyaluronic acid injection who underwent ICGA assessment before and immediately after initial rescue therapy. ICGA was performed as part of prior clinical evaluation to visualize local tissue perfusion in real time. Quantitative perfusion-related parameters were obtained using imaging analysis software.

The analysis will compare ICGA-based perfusion changes within the same patient before and after initial rescue therapy. The study will also explore whether baseline perfusion status and early perfusion recovery are associated with subsequent clinical management and tissue outcomes. Patients may be descriptively stratified according to whether additional intervention was required after initial rescue therapy.

All data will be collected retrospectively and de-identified before analysis. The study does not alter previous clinical decision-making and does not expose participants to additional physiological risk. The main study-related risk is potential loss of confidentiality, which will be minimized through de-identification, restricted access to study data, and secure data storage.

Inclusion Criteria:

• History of facial hyaluronic acid injection.
• Clinical diagnosis of facial vascular embolism after hyaluronic acid injection, with symptoms or signs such as pain, skin color change, livedo-like discoloration, delayed capillary refill, or tissue ischemia.
• Received initial rescue treatment at the study center.
• Had indocyanine green angiography imaging performed before and immediately after initial rescue treatment as part of routine clinical care.
• Had sufficient medical records and follow-up information available to assess subsequent treatment and tissue outcomes.

Exclusion Criteria:

• Incomplete indocyanine green angiography imaging data.
• Insufficient medical records or follow-up information to assess the main study outcomes.
• Missing key clinical information needed for study analysis.
• Duplicate records or records with concerns about data reliability.
• The patient or legal representative explicitly objected to the use of historical clinical data for this study, if applicable under local ethics requirements.

The study population consists of consecutive patients treated at the Center for Wound Repair and Tissue Regeneration, Plastic Surgery Hospital, Chinese Academy of Medical Sciences, for facial vascular embolism following hyaluronic acid injection between July 2025 and March 2026. Participants will be identified retrospectively from existing medical records, indocyanine green angiography imaging data, treatment records, and follow-up documentation generated during routine clinical care.