Balanced immune responses in the eyes are crucial to preserve vision. The ocular immune system has long been considered distinct, owing to the so-called ‘immune privilege’ of its component tissues. More recently, intravital imaging and transcriptomic techniques have reshaped scientific understanding of the ocular immune landscape, such as revealing the specialization of immune cell populations in the various tissues of the eye. As knowledge of the phenotypes of corneal and retinal immune cells has evolved, links to both the systemic immune system, and the central and peripheral nervous systems, have been identified. Using intravital imaging, T cells have recently been found to reside in, and actively patrol, the healthy human cornea. Disease-associated retinal microglia with links to retinal degeneration have also been identified. This Review provides an updated guide to the ocular immune system, highlighting current knowledge of the immune cells that are present in steady-state and specific diseased ocular tissues, as well as evidence for their relationship to systemic disease. In addition, we discuss emerging intravital imaging techniques that can be used to visualize immune cell morphology and dynamics in living human eyes and how these could be applied to advance understanding of the human immune system.

眼睛中平衡的免疫反应对于保护视力至关重要。长期以来，人们一直认为眼部免疫系统是独特的，因为它的组成部分组织具有所谓的“免疫特权”。最近，活体成像和转录组学技术重塑了对眼部免疫景观的科学理解，例如揭示了免疫细胞群在眼睛各种组织中的特化。随着对角膜和视网膜免疫细胞表型的认识不断发展，已经确定了与全身免疫系统以及中枢和周围神经系统的联系。使用活体成像，最近发现 T 细胞驻留在健康的人类角膜中并积极巡逻。还确定了与视网膜变性相关的疾病相关视网膜小胶质细胞。本综述提供了眼部免疫系统的最新指南，重点介绍了存在于稳态和特定患病眼组织中的免疫细胞的当前知识，以及它们与全身性疾病关系的证据。此外，我们还讨论了可用于可视化活人眼中免疫细胞形态和动力学的新兴活体成像技术，以及如何应用这些技术来促进对人类免疫系统的理解。