The immune system is involved in many age-related pathological changes, also plays an important role in tissue regeneration after injury. But no immune involvement has been discussed regarding cataract since it is presumed that lens has no source of immune cells as an avascular zone. Latest research has challenged the longstanding view of the lens as an immune-privileged tissue, revealing the presence of resident immune cells and active immune responses within the lens. Thus, we summarized the immune involvement in maintaining lens homeostasis, which may be a deleterious role in the induction of lens opacification if inappropriately activated. Furthermore, bioengineer-based immunomodulatory therapies to fine-tune the micro immune environment within lens may be future strategies for in situ lens regeneration, as a novel treatment for cataract.