Abstract
Vitreous humour is a biologically weak immune cavity of the eye, and is in some way isolated from pathogens of the rest of the organism due to a series of special immunological privileges. However, it is a place where processes of varied ethiology (immune, infectious or neoplastic) can develop indirectly due to leakage or release of molecules or even cells into the vitreous chamber, or may be the receptacle of molecules derived from processes developed in other organs in close contact with the vitreous (such as the retina or other underlying layers such as the choroid), which makes the vitreous body an accessible place for diagnosis and with less potential for side effects for analysis than other adjacent eye structures. This article reviews the most frequent pathologies that requires vitreous diagnosis, the most commonly used approaches for sampling and the diagnostic tests that can be performed on vitreous samples.