Intraocular Fluid

  • Fluid present in eyeball.
  • Responsible to maintain eyeball shape.
  • Two types: a) Aqueous humor and b) Vitreous humor

Aqueous Humor

  • Fluid thin in nature present in front of retina.
  • Space is present in between lens and cornea.
  • Aqueous humor fills that space.
  • The space also divides into anterior and posterior chamber.
  • Iris divides the space into two chambers.
  • Pupil helps to communicate both these chambers.

Eye Pressure - American Academy of Ophthalmology

Image source: aao

Properties of Aqueous humor

  • Volume of this fluid is 0.13 ml.
  • It is alkaline in nature with pH 7.5.
  • It has viscosity of 1.029.
  • This fluid has refractive index of 1.34.

Composition of Aqueous humor

  • It is composed of water and solids.
  • Water makes 98.7% and solids make 1.3%.
  • Solids contain different organic and inorganic substances.
  • Albumin, globulin, glucose, lactate, pyruvate, urea present as organic substances.
  • Calcium, sodium, magnesium, chlorides, potassium, bicarbonates, phosphates make inorganic part.

Fluid System of the Eye- Intraocular Fluid

Image source: brainkart

Aqueous humor formation

  • Ciliary processes forms this fluid.
  • Plasma within capillary network of ciliary processes forms it.
  • Diffusion, ultrafiltration and active transport are the involved process.
  • Transport occurs through epithelial cells that lines ciliary processes.
  • This fluid then passes through suspensory ligaments.
  • From there, it reaches the posterior chamber.
  • Fluid finally comes to anterior chamber via pupil.
  • It is a continuous process i.e., formation of this fluid.
  • In one minute, 2-3 µL of fluid is formed.
  • In anterior chamber, this fluid is about 230-250 µL.
  • 50-60 µL is the amount present in posterior chamber.

Drainage of aqueous humor

Anterior chamber → limbus (angle between cornea and iris) →  meshwork of trabeculae → canal of schlemn →

→ anterior ciliary vein → venous system.

( meshwork of trabeculae –  situated near the junction of iris and cornea)

                                                   Fig: flowchart of drainage of aqueous humor

Biology | Free Full-Text | Lymphatics in Eye Fluid Homeostasis: Minor  Contributors or Significant Actors? | HTML

Image source: mdpi

Functions of Aqueous humor

  • Shape of eyeball maintained.
  • Intraocular pressure maintained.
  • Lens and cornea gets nutrients, oxygen and electrolytes.

(Lens and cornea are avascular structures)

  • Lens and cornea contains metabolic end products.
  • They are removed by this fluid.

Vitreous humor

  • Fluid present in the space between lens and retina.
  • Comprises 2/3rd of the eye volume.
  • Hydrophilic, transparent, inert, colorless and gel structure.
  • 99% of this fluid is water and 1 % is protein, sugars, salts, collagen, etc.
  • Highly viscous and gelatinous, also called vitreous body.
  • Fine fibrillar network of proteoglycan molecules forms this fluid.
  • Albumin and hyaluronic acid are the major components.
  • These substances enter the vitreous body from blood.
  • Diffusion helps to transfer these substances.

Functions of vitreous humor

  • Maintain the round shape of eyeball.
  • Center of eyes remain clear so light can get to the retina and vision begins.
  • Help in absorbing unexpected disturbances to the eye.
  • Help to prevent eye damage.
  • Pressure exerted by vitreous humor keeps the retina stable and in place.





Intraocular Fluid