Vitreous Humor: The Gel That Maintains Eye Shape

Vitreous Body: Structure and Function

The vitreous humor (vitreous body) is a transparent, avascular gel filling the posterior segment (behind the lens, in front of retina). Composed of:

• 99% water.
• Collagen type II fibrils (structural scaffold).
• Hyaluronic acid (hydration, viscosity).
• Few cells: hyalocytes (phagocytic).

Functions

1. Maintains globe shape and intraocular pressure.
2. Transmits light (refractive index 1.336).
3. Supports retina (tamponade).
4. Metabolic exchange (diffusion).

Aging Changes

• Syneresis (liquefaction) → posterior vitreous detachment (PVD) → floaters, flashes.
• PVD can cause retinal tears → detachment (emergency).

Clinical Procedures

• Vitrectomy: surgical removal for hemorrhage, detachment, macular hole, diabetic traction.
• Intravitreal injections (anti-VEGF, steroids) traverse vitreous.