Skip to main content
Clear
Find glasses using an image
  • Find a store
  • Menu
Specsavers logo
  • My account Log in
    • Favourites
    • Express re-order
    • Orders
    • My details
    • Payment methods
    • Log out
  • Re-order contact lenses
    • Glasses
        • Glasses
        • Women
        • Men
        • Unisex
        • Kids
        • Glasses
        • Sunglasses
        • Designer brands
        • Designer glasses
        • Our glasses collections
        • Glasses to suit your face shape
        • Vivienne Westwood collection
        • Find your glasses
        • Do I Need Glasses?
        • Lens guide
        • Buyer's guide
        • Order Replacement glasses
        • Lens extras and treatments
        • #loveglasses blog
        • Do blue light glasses work?
        • Accessories
    • Contact lenses
        • Contact lenses
        • Product type
        • View all
        • Daily
        • Monthly
        • Information
        • Free contact lens trial
        • Direct debit scheme
        • Express Re-order
        • easycare FAQs
        • easycare login
        • Buying contact lenses
        • Contact lens guide
        • Express re-order
    • Eye tests
        • Eye tests
        • Services
        • Book an eye test
        • Ways we can help remotely
        • Home eye tests
        • Eyecare at work
        • OCT Scan
        • DVLA eye tests
        • NHS funded eye tests
        • Information
        • Your eye test explained
        • Eye health
        • Eye conditions & symptoms
        • Children's eyecare
        • Care Hub (COVID-19 Information)
        • Your store visit explained
        • Your prescription explained
        • Help
        • Information for GPs
        • Ask the expert
        • How to obtain your prescription
        • FAQs
    • Hearing
        • Hearing
        • Hearing
        • Book a free hearing test
        • Earwax removal
        • Hearing tests
        • Free online hearing test
        • Products
        • Hearing aids
        • Hearing aid prices
        • Buy hearing aid batteries
        • NHS funded hearing aids
        • Great offers
        • Information
        • What happens in a hearing test
        • All about earwax
        • All about ear health
        • Hearing loss
    • Home visits
        • Home visits
        • Home eye tests
        • About home visits
        • Home hearing tests
        • Eligibility
        • Request a home visit
        • Eye tests in care homes
        • FAQs
        • Meet the teams
        • GenerationWow
    • Offers
        • Offers
        • Glasses
        • Designer glasses for teens
        • Complete glasses from £19
        • Student glasses discount
        • Free pair for kids
        • 20% off glasses for over-60s
        • 2 for 1 glasses from £69
        • 2 for 1 designer glasses
        • 2 for 1 glasses & sunglasses
        • Lenses
        • Free varifocals
        • Polarising lenses only £59
        • Free UltraClear SuperClean
        • Free Thin + Light lenses
        • Free Reactions
        • 2 for 1 varifocal glasses
        • Contact lenses
        • Free contact lens trial
        • 50% off glasses with contact lenses
        • First month's free contact lenses
        • Hearing
        • Best value for hearing aids
        • Invisible hearing aids from £495
        • Free hearing tests
        • Rechargeable hearing aids from £995
        • Hearing product bundles
    • Book appointment
    • Find a store
    • Re-order contact lenses
    • Log in
    • My account
    • Favourites
    • Log out
  • Book appointment Book appointment
Age & gender
  • Women
  • Men
  • Unisex
  • Kids
Type
  • Glasses
  • Sunglasses
  • Designer glasses
  • Designer brands
  • Our glasses collections
  • Vivienne Westwood collection
  • Glasses to suit your face shape
Guides
  • Find your glasses
  • Buyer's guide
  • Lens guide
  • Lens extras and treatments
  • Do blue light glasses work?
  • Order Replacement glasses
  • Accessories
  • Do I Need Glasses?
  • #loveglasses blog
Vivienne Westwood collection
Glasses and sunglasses
2 for 1 from £149
Browse the collection
Product type
  • Daily
  • Monthly
  • Multifocal
  • Toric
  • View all
Brand
  • easyvision
  • Acuvue
  • Focus
  • View all
Information
  • Direct debit scheme
  • easycare FAQs
  • Buying contact lenses
  • Contact lens guide
  • Free contact lens trial
  • FAQs
  • Express Re-order
  • easycare login
Specsavers express re-order
Buy Online
Buy your contact lenses online and get free delivery
Buy Now
Services
  • Book an eye test
  • Ways we can help remotely
  • Home eye tests
  • Eyecare at work
  • OCT Scan
  • DVLA eye tests
  • NHS funded eye tests
Information
  • Your eye test explained
  • Eye health
  • Eye conditions & symptoms
  • Children's eyecare
  • Care Hub (COVID-19 Information)
  • Your store visit explained
  • Your prescription explained
Help
  • Information for GPs
  • Ask the expert
  • How to obtain your prescription
  • FAQs
Book appointment
Book an OCT scan
Our OCT scans give the most detailed look at your eyes ever - add one to your next eye test today.
Book now
Services
  • Book a free hearing test
  • Hearing tests
  • Earwax removal
  • Hearing aid aftercare
  • Free online hearing test
  • Hearing
Products
  • Hearing aid prices
  • Hearing aids
  • Hearing aid brands
  • NHS funded hearing aids
  • Buy hearing aid batteries
  • Great offers
  • All about hearing protection
Information
  • What happens in a hearing test
  • All about earwax
  • All about ear health
  • Hearing loss
  • GP guidance
  • Download an information sheet
Book appointment
Book appointment
Check out our Advance range - Latest technology with invisible aids from £495.
Book now
Home visits
  • About home visits
  • Eligibility
  • Request a home visit
  • Eye tests in care homes
  • FAQs
  • Meet the teams
  • Home eye tests
  • Home hearing tests
  • GenerationWow
Check your eligibility
Free home eye test
Check if you or a loved one qualify for a free home eye test
Check eligibility
Glasses
  • 2 for 1 glasses from £69
  • 2 for 1 designer glasses
  • 2 for 1 glasses & sunglasses
  • 20% off glasses for over-60s
  • Free pair for kids
  • Designer glasses for teens
  • Complete glasses from £19
  • Student glasses discount
Lenses
  • 2 for 1 varifocal glasses
  • Free Reactions
  • Free Thin + Light lenses
  • Free UltraClear SuperClean
  • Free varifocals
  • Polarising lenses only £59
Contact lenses
  • First month's free contact lenses
  • 50% off glasses with contact lenses
  • Free contact lens trial
Hearing
  • Invisible hearing aids from £495
  • Rechargeable hearing aids from £995
  • Free hearing tests
  • Best value for hearing aids
  • Hearing product bundles
  1. Home

Understanding glaucoma: what is the aqueous humour?

Glaucoma is linked to a build-up of pressure in the eye caused by an imbalance in the production and drainage of a fluid called the aqueous humour.

The increased pressure can damage the optic nerve, which can create blind spots in the visual field (small areas of your vision where there is no image detection). If left untreated, glaucoma can lead to irreversible vision loss.1 But in order to understand the condition and how it can progress, it’s important to know what causes it, and the important role aqueous humour plays in this.

What is the function of aqueous humour?

Aqueous humour is a thin, watery fluid produced by the eye and, in a healthy eye, it’s in a constant cycle of production and drainage. The aqueous humour is 99.9% water and 0.1% nutrients such as glucose, proteins and vitamins. These nutrients nourish the cornea and lens and keep the eye healthy, as well a protect the cornea against the wind, pollen, dust, and pathogens.

This fluid fills the spaces between the cornea and iris (anterior chamber) and the iris and lens (posterior chamber), which gives the eye its round shape and controls intraocular pressure (IOP).2 It’s secreted by a structure called the ciliary body which is an extension of the iris (the coloured portion of the eye).

How does aqueous humour control IOP?

In a healthy eye, a certain amount of aqueous humour flows into the eye and the same amount drains out. This process keeps the IOP within ‘normal limits’.

However, variations in the production or outflow of aqueous humour can lead to significant changes in intraocular pressure. In most forms of glaucoma, vision loss occurs due to an increase in IOP caused by an imbalance in the production or outflow of the aqueous humour, and it’s this build-up of pressure which can cause permanent damage to the optic nerve.3

How is aqueous humour produced and drained?

Aqueous humour is actively secreted into the eye by the ciliary body (the ciliary body also controls the shape of the lens). This is the part of the eye that connects the cornea to the choroid (the vascular layer of the eye). Active secretion is the most important part of aqueous humour production and this is controlled by enzymes and proteins deep inside the ciliary body.4

The fluid leaves the eye through two principle routes: the trabecular meshwork (an area of tissue at the base of the cornea) and the uveoscleral pathway.

The trabecular meshwork is responsible for 75% of the resistance to aqueous humour outflow. If this site becomes blocked by a deposit of proteins or other substances, for instance, an imbalance is caused in the production and drainage cycle — leading to an increase in IOP.

The second pathway for aqueous humour drainage, the uveoscleral pathway, is relatively independent of IOP, but effective drainage via the uveoscleral pathway decreases with age.4 Age, potentially as a result, is also one of the key risk factors for glaucoma development.

How does aqueous humour help inform glaucoma treatment?

The role of the aqueous humour in the development of glaucoma is well known, but the type of glaucoma will usually depend on which part of the production or drainage system has been affected. Current treatments for glaucoma focus on lowering the IOP by increasing the outflow of aqueous humour or suppressing its production.

Eye drops are the most common form of glaucoma treatment and can be tailored to glaucoma type and need. For example, eye drops that contain carbonic anhydrase inhibitors (e.g. dorzolamide) and beta-blockers (e.g. timolol) decrease the production of aqueous humour by the ciliary body. Prostaglandins (e.g. latanoprost), on the other hand, increase the outflow of aqueous humour through the uveoscleral pathway and trabecular meshwork. While eye drops containing alpha-adrenergic agonists (e.g. brimonidine) perform both functions.

Surgical treatments for glaucoma can also be used to lower IOP by increasing aqueous humour drainage or reducing its formation.

Some laser treatments target the part of the ciliary body responsible for aqueous humour production to lower IOP. Other procedures such as trabeculectomy or laser trabeculoplasty modify the trabecular meshwork to decrease outflow resistance.

Glaucoma shunts are sometimes recommended for some patients to bypass the trabecular meshwork and improve drainage. Another option is canaloplasty — a procedure that opens up the uveoscleral pathway and increases aqueous humour outflow through existing pathways.4

If you have any concerns and queries regarding glaucoma treatment, please don’t hesitate to ask your optometrist. They will be able to advise you effectively, as well as explain more about the function of aqueous humour.

If you found this information about aqueous humour helpful, however, then do browse our dedicated glaucoma resources. There’s a wealth of expert-led content explaining the causes of glaucoma, glaucoma diagnosis and glaucoma treatment.

References

1. University of Washington. (no date). Eye Diseases – Glaucoma. [Online]. Available at: https://faculty.washington.edu/chudler/glaucoma.html [Accessed 6 August 2019].
2. Vision Eye Institute. (no date). The Aqueous Humour. [Online]. Available at: https://visioneyeinstitute.com.au/eyematters/aqueous-humour/ [Accessed 6 August 2019].
3. American Academy of Ophthalmology. (no date). Causes of Glaucoma. [Online]. Available at: https://www.aao.org/eye-health/diseases/glaucoma-causes [Accessed 6 August 2019].
4. Goel, M., Picciani, R. G., Lee, R. K., & Bhattacharya, S. K. (2010). Aqueous humor dynamics: a review. The open ophthalmology journal, 4, 52–59. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3032230/ [Accessed 6 August 2019].

Josie Forte
DOptom BSc(Hons) MCOptom

Josie is an optometrist registered with the UK General Optical Council and New Zealand Board of Optometrists and Dispensing Opticians. She graduated from Cardiff… Read more

Causes of glaucoma

Find out more

Diagnosis of glaucoma

Find out more

Meet our experts

Find out more

Glaucoma hub
 

Find out more

Book an appointment
  • Browse
    • Glasses
    • Designer glasses
    • Contact lenses
    • Hearing aids
    • Offers
    • Gift vouchers
  • Services
    • Book an eye test
    • OCT scans in store
    • Eye tests at home
    • Eyecare at work
    • Book a hearing test
    • Hearing tests at home
    • Information for GPs
  • COVID-19 Information
    • Keeping you safe in store
    • Glasses fogging up advice
    • Your new in store experience
  • About
    • About Specsavers
    • Contact us
    • Careers
    • Hindsight report
    • Our year in numbers 2020/21
    • Sustainability
    • Sitemap
    • Specsavers promise
  • © Specsavers 2022
  • Legal policies
  • Privacy policy
  • International sites
  • Modern Slavery Act
  • 22.04.0