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Anatomy of the Vitreous
Anatomy
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81. Clinical Analogy - The Vitreous as a Structured Hydrogel
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1Imagine a firm, transparent jelly dessert moulded perfectly inside a glass bowl (the eye). At the centre it is soft and fluid; at the periphery and over the gel surface it is denser, almost leathery. The jelly is held in shape not by a rigid wall but by an intricate scaffold of type-II collagen fibrils cross-linked by hyaluronic acid chains - like steel rebar embedded in a water-gel matrix. Shake the bowl gently and the jelly oscillates with characteristic after-movement (vitreous lag). With age, the scaffold collapses, water pools (synchysis), and the surface membrane can peel off the retina - causing the entire clinical spectrum of PVD, floaters, tractional tears, and macular holes.
2. Gross Anatomy
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1Volume and Shape
- The vitreous body (corpus vitreum) is the largest single structure of the eye by volume: ~4.0 mL (range 3.5–5.5 mL).
- It occupies the posterior segment (posterior to the lens–zonule–ciliary body plane). Shape: ovoid, with a concave anterior surface (the patellar fossa or hyaloid fossa) that cradles the posterior lens.
- Dimensions: Axial ~16.5 mm, transverse ~17 mm at equator.
- Weight: ~4 g.
- Refractive index: 1.336 (very close to aqueous humor; optically negligible).
Zones Within the Vitreous Body
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1| Zone | Location | Characteristics | Clinical Relevance |
|---|---|---|---|
| Cortex (vitreous cortex) | • Peripheral 100–300 µm shell | • High collagen density • Hyalocytes present • Anterior cortex thinner | • Plane of posterior vitreous detachment (PVD) separation • Scaffold for proliferative membranes |
| Vitreous base | • Straddles ora serrata • 2 mm anterior • 3 mm posterior | • Strongest vitreoretinal attachment • Collagen fibrils interdigitate with retinal internal limiting lamina | • Usually remains attached in posterior vitreous detachment (PVD) • Site of traction-related peripheral retinal tears • Vitreous-base shaving may be used in selected vitrectomy procedures |
| Central vitreous (vitreous body) | • Core gel | • Less dense • Liquefaction begins centrally and increases with age | • Pocket of vitreous liquefaction • Asteroid hyalosis deposits suspended throughout vitreous cavity |
| Cloquet's canal | • Sinus-like tract from patellar fossa to area of Martegiani | • Remnant of primary vitreous (hyaloid artery) | • Seen on optical coherence tomography (OCT) • Persistent hyaloid vessels may persist abnormally as developmental remnants |
| Area of Martegiani | • Ring around optic disc • ~2 disc diameters | • Funnel-shaped widening of Cloquet's canal | • Weiss ring forms here in posterior vitreous detachment (PVD) • Prepapillary vitreous traction |
| Zone | Location | Characteristics | Clinical Relevance |
|---|---|---|---|
| Cortex (vitreous cortex) | • Peripheral 100–300 µm shell | • High collagen density • Hyalocytes present • Anterior cortex thinner | • Plane of posterior vitreous detachment (PVD) separation • Scaffold for proliferative membranes |
| Vitreous base | • Straddles ora serrata • 2 mm anterior • 3 mm posterior | • Strongest vitreoretinal attachment • Collagen fibrils interdigitate with retinal internal limiting lamina | • Usually remains attached in posterior vitreous detachment (PVD) • Site of traction-related peripheral retinal tears • Vitreous-base shaving may be used in selected vitrectomy procedures |
| Central vitreous (vitreous body) | • Core gel | • Less dense • Liquefaction begins centrally and increases with age | • Pocket of vitreous liquefaction • Asteroid hyalosis deposits suspended throughout vitreous cavity |
| Cloquet's canal | • Sinus-like tract from patellar fossa to area of Martegiani | • Remnant of primary vitreous (hyaloid artery) | • Seen on optical coherence tomography (OCT) • Persistent hyaloid vessels may persist abnormally as developmental remnants |
| Area of Martegiani | • Ring around optic disc • ~2 disc diameters | • Funnel-shaped widening of Cloquet's canal | • Weiss ring forms here in posterior vitreous detachment (PVD) • Prepapillary vitreous traction |
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Keep reading Anatomy of the Vitreous
22 more sections are included with the Clinical plan.
- Microscopic Structure - The Molecular Scaffold
- Hyaluronic Acid (HA)
- Hyalocytes
- Opticin & Other Proteoglycans
- Vitreoretinal Interface (VRI)
- Anomalous PVD and Vitreoschisis