Aqueous humor

The aqueous humor and vitreous humor are the two major fluids in the eye, and they’re essential for maintaining eye shape, pressure, and internal health—but they’re very different in structure, function, and location.

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💧 Aqueous Humor

📍 Location:

• Found in the anterior segment of the eye:

  • Anterior chamber (between cornea & iris)

  • Posterior chamber (between iris & lens)

🧬 Produced By:

• Ciliary processes of the ciliary body

🔁 Flow Pathway:

1. Secreted into the posterior chamber

2. Flows through the pupil into the anterior chamber

3. Drains through the:

   • Trabecular meshwork

   • Canal of Schlemm

   • Then into episcleral veins

🎯 Functions:

• Maintains intraocular pressure (IOP)

• Provides nutrients (glucose, amino acids) to avascular structures like the lens and cornea

• Removes waste products

• Keeps the anterior chamber optically clear

🧾 Clinical Relevance:

• Glaucoma: Increased IOP due to impaired outflow of aqueous humor

• Hyphema/Hypopyon: Blood or pus in aqueous—seen in trauma or infection

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🟠 Vitreous Humor (Vitreous Body)

📍 Location:

• Fills the large space in the posterior segment of the eye:

  • Between the lens and the retina

🧬 Structure:

• Gel-like, transparent

• Composed of:

  • ~99% water

  • Collagen

  • Hyaluronic acid

  • Small number of cells (hyalocytes)

🎯 Functions:

• Maintains the shape of the globe

• Provides a shock-absorbing cushion

• Holds the retina in place against the choroid

• Transmits light to the retina

⚠️ Important Points:

• Formed mostly during embryonic development; not constantly regenerated like aqueous humor

• Attached to retina at several key points:

  • Optic disc, macula, retinal vessels, and ora serrata

🧾 Clinical Relevance:

• Posterior vitreous detachment (PVD): Common with age—can cause floaters or flashes

• Vitreous hemorrhage: Blood in vitreous, often due to diabetic retinopathy

• Retinal detachment: Vitreous traction can tear retina

• Floaters: Shadows from small collagen clumps in aging vitreous

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🔍 Quick Comparison Table:

Feature	Aqueous Humor	Vitreous Humor
Location	Anterior & posterior chambers	Posterior segment (vitreous cavity)
Consistency	Watery	Gel-like
Produced by	Ciliary processes	Mostly prenatal formation
Drains via	Trabecular meshwork → Schlemm’s canal	No significant drainage pathway
Function	IOP, nutrition, waste removal	Eye shape, retina support, light passage
Related Disease	Glaucoma	PVD, floaters, retinal detachment