The vitreous humour is normally a transparent substance that occupies the vitreous cavity. It is the biggest structure of the eye in terms of volume. Its primary purpose is to maintain the structural stability of the eye and also to assume a damping function if outside pressure is applied. It is partially attached to some eye structures such as the retina, papilla and the dorsal side of the lens. If the vitreous humour becomes cloudy with age or due to pathological changes, this results in light scatter and hence lower visual acuity, since the light that hits the retina is less focused. However, the exact function of the vitreous humour has not been fully clarified.