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.

眼睛平衡的免疫反应对于保护视力至关重要。由于其组成组织具有所谓的“免疫特权”，长期以来，眼部免疫系统一直被认为是独特的。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，例如揭示了眼部各种组织中免疫细胞群的专门化。随着对角膜和视网膜免疫细胞表型的了解不断发展，人们已经确定了其与全身免疫系统以及中枢和周围神经系统的联系。通过活体成像，最近发现 T 细胞驻留在健康的人类角膜中，并积极巡逻。与视网膜变性有关的疾病相关视网膜小胶质细胞也已被发现。这篇综述提供了眼部免疫系统的最新指南，强调了目前对稳态和特定患病眼部组织中存在的免疫细胞的了解，以及它们与全身性疾病关系的证据。此外，我们还讨论了新兴的活体成像技术，这些技术可用于可视化活体人眼中的免疫细胞形态和动态，以及如何应用这些技术来增进对人类免疫系统的了解。