Periocular refers to the externally visible region of the face that surrounds the eye socket. This feature-rich area can provide accurate identification in unconstrained or uncooperative scenarios, where the iris or face modalities may not offer sufficient biometric cues due to factors such as partial occlusion or high subject-to-camera distance. The COVID-19 pandemic has further highlighted its importance, as the ocular region remained the only visible facial area even in controlled settings due to the widespread use of masks. This paper discusses the state of the art in periocular biometrics, presenting an overall framework encompassing its most significant research aspects, which include: (a) ocular definition, acquisition, and detection; (b) identity recognition, including combination with other modalities and use of various spectra; and (c) ocular soft-biometric analysis. Finally, we conclude by addressing current challenges and proposing future directions.

翻译：眼眶周围区域指面部环绕眼窝的外部可见部分。这一特征丰富的区域在非约束或非协作场景中能够提供准确的识别，当虹膜或人脸模态因部分遮挡、被摄体与相机距离过远等因素无法提供足够生物特征线索时，其优势尤为突出。COVID-19疫情进一步凸显了该区域的重要性——即使在受控环境中，因口罩的广泛使用，眼部区域成为唯一可见的面部区域。本文论述了眼眶周围生物特征识别技术的最新进展，提出了涵盖其最重要研究领域的整体框架，包括：(a) 眼部区域定义、采集与检测；(b) 身份识别（含与其他模态的融合及多光谱应用）；(c) 眼部软生物特征分析。最后，我们总结了当前面临的挑战并展望了未来研究方向。