Vitreous body

The vitreous body, whose name comes from the Latin word for "glassy," is the clear, jelly-like substance that occupies the space between the eye's lens and retina, known as the vitreous chamber. This structure, also called the vitreous humor or simply the vitreous, accounts for about four-fifths of the eyeball's total volume. In a typical adult human eye, it measures roughly 4 mL, though this amount varies widely from person to person, depending on the eye's axial length and refractive condition. For instance, highly myopic eyes, which are longer than average, can hold over 9–10 mL of vitreous, while hyperopic eyes, which are shorter, may contain only about 3–4 mL.

The vitreous humor is a transparent, colorless, gelatinous mass. Near the center, it has a more fluid consistency, while toward the edges it becomes more gel-like. It is encased by a layer of collagen called the vitreous membrane (or hyaloid membrane or vitreous cortex), which separates it from the rest of the eye. This membrane lies in contact with the retina, and collagen fibrils anchor the vitreous at several points: the optic nerve disc, the ora serrata (where the retina ends at the front), the Wieger-band on the back of the lens, the lens capsule, retinal blood vessels, and the macula—the part of the retina responsible for sharp central vision. In rats, aquaporin 4 in Müller cells helps transport water into the vitreous.

The vitreous features several distinct anatomical landmarks. On its surface, the patella fossa is a shallow, saucer-like depression at the front where the lens sits, separated from it by Berger's space. The ligamentum hyaloideocapsulare, or Wieger's ligament, is a circular thickening of vitreous about 8–9 mm in diameter that outlines this fossa. The anterior hyaloid is the vitreous surface in front of the ora serrata; it connects with and wraps around the zonular fibers, extending forward between the ciliary processes. The vitreous base is a denser cortical area firmly attached to the back 2 mm of the pars plana and the front 2–4 mm of the retina. The posterior hyaloid surface lies close against the retina's internal limiting membrane, with firm attachments along blood vessels and at sites of retinal degeneration. The space of Martegiani is a funnel-shaped area over the optic disc with a condensed edge. Cloquet's canal is a narrow, 1–2 mm wide channel running through the vi