The vitreous humor is a transparent, colorless, gelatinous mass that fills the space in the eye between the lens and the retina.

Collagen fibrils attach the vitreous at the optic nerve disc and the ora serrata[1] (where the retina ends anteriorly), at the Wieger-band, the dorsal side of the lens.

The vitreous also firmly attaches to the lens capsule, retinal vessels, and the macula, the area of the retina which provides finer detail and central vision.

It is composed mostly of phagocytes, which remove unwanted cellular debris in the visual field, and hyalocytes, which turn over the hyaluronan.

Despite having little solid matter, the fluid is substantial enough to fill the eye and give it its spherical shape.

This contrasts with the aqueous humour, which is more fluid, and the lens, on the other hand, which is elastic in nature and is tightly packed with cells.

Central vitreous liquefies, fibrillar degeneration occurs, and the tracts break up (syneresis).

Similarly, the gel may liquefy, a condition known as synaeresis, allowing cells and other organic clusters to float freely within the vitreous humour.

[15][16][17] The metabolic exchange and equilibration between systemic circulation and vitreous humour is so slow that vitreous humour is sometimes the fluid of choice for postmortem analysis of glucose levels or substances which would be more rapidly diffused, degraded, excreted or metabolized from the general circulation.