The immune system is central to almost every aspect of human health and disease, with tissues accepted as the determinative site of immune cell function. Biopsies have provided valuable insight but remain static snapshots that miss the critical temporal dynamics of immune responses. The ultimate aspiration would be to observe real-time, unperturbed, immune cell behaviour deep within the tissues of patients. The eye can realise this goal, as the transparent ocular tissues are inherently suited for repeated in vivo imaging across time.