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Aqueous Humour

Aqueous humour is a clear, watery fluid that fills the anterior and posterior chambers of the eye. It is produced by the ciliary processes of the ciliary body, a structure located behind the iris, and is secreted into the posterior chamber. From there, it flows through the pupil into the anterior chamber, where it is absorbed by the trabecular meshwork and drained out of the eye through the Schlemm’s canal.

In open-angle glaucoma, fluid does not flow freely through the trabecular meshwork, resulting in increased intraocular pressure, optic nerve injury, and visual loss. Glaucoma is characterized by high intraocular (eye) pressure in the majority of cases, but not all. When part of the fluid is generated by the ciliary body of the eye, aqueous humour flows freely.

Aqueous humour is an optically transparent, negligibly alkaline visual fluid that is constantly created from plasma by the ciliary body’s epithelial cells. The elements helping the aqueous humour formation contain protein, y-globulins, and albumin, relatively less than plasma. Besides this, lactic acid, immunoglobulin G, ascorbic acid and glucose are also present.


Aqueous Humour functions


The aqueous humour plays an important role in the eyeball, includes the following points:

  • The avascular ocular tissues, such as the posterior cornea, trabecular meshwork, lens, and anterior vitreous, get sustenance (such as amino acids and glucose). Ascorbate is transported in the anterior segment and acts as an antioxidant.
  • Inflates the cornea, increasing defence from dirt, air, pollen, and certain infections.
  • Maintains Intraocular pressure (IOP)
  • Refers to the refractive index.
  • Precludes the dryness of the eyes.
  • It removes waste products and debris


Aqueous Humour Production


The ciliary body generates 2.5L of aqueous humour every minute on typical. The following are the processes that are involved in aqueous humour production:

  1. Diffusion.
  2. Ultrafiltration.
  3. The secretion that is active.


Diffusion and ultrafiltration are inert activities. However, they help gather ultrafiltrate plasma inside the ciliary bodies stromal. The ciliary body epithelium then emits aqueous fluid further into the posterior aqueous humour chamber on a regular basis. In this active process, a Na+/K+- ATPase hydrolyses ATP for energy.

It’s worth noting that the sympathetic nervous system has an impact on aqueous humour production. The stimulation of beta-2 and alpha-2 adrenoceptors, accordingly enhances and lowers the genre of aqueous humour.


Aqueous Humour’s Related Disease


The aqueous fluid drains from the aqueous chamber into the Schlemm canal, which subsequently empties to the episcleral veins via the trabecular meshwork. Schlemm’s canal (SC) is a lymphatic vessel-like circular structure in the scleral sulcus, directly beyond the corneoscleral junction. The AC interacts with the interior layer of the SC, whereas the episcleral veins connect with the external perimeter.

The trabecular meshwork empties the bulk of aqueous humour, while the uveoscleral pathway drains just around 10%. The aqueous humour flows into the suprachoroidal space, which would be a gap in between the sclera and the choroid via the iris and the front side of the ciliary muscle. Because the fluid is generally 15 mmHg (0.6 inHg) over air pressure, it flows freely when injected with a syringe. If the fluid leaks, the typical eye’s hardness is undermined, causing the cornea to fold and droop.


Glaucoma is a general term used to describe a group of eye disorders that damage your optic nerve. It’s the most common form of optic nerve damage leading to vision loss.

In most cases, fluid builds up in the front part of your eye. This extra fluid puts pressure on your eye, gradually damaging your optic nerve. The name of this pressure is intraocular pressure (IOP), or eye pressure. Some people have normal eye pressure and still get glaucoma. Untreated glaucoma or poorly managed glaucoma can lead to permanent and irreversible vision loss and blindness.

Most people develop glaucoma in both eyes, although the disease initially may be worse in one eye. With open-angle glaucoma, one eye may have moderate or severe damage, while the other eye may be mildly affected. People with closed-angle glaucoma in one eye have a 40% to 80% chance of developing the same type of glaucoma in the other eye within five to 10 years.


Ayan Das

A passionate Optometry student with a motive to become the best Optometrist...

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