Aqueous Humor & Vitreous Humor

What are aqueous humor and vitreous humor?

One definition of the word “humor” is “a bodily fluid,” and this is true for the fluids found in your eye — the aqueous humor and the vitreous humor.

Your eyes continuously make aqueous humor, the clear fluid in the front part of your eye. The aqueous humor keeps your eye inflated and provides nourishment.

The vitreous humor, also called vitreous fluid, is a clear gel-like substance that’s located in your eye. It takes up the space between your eye’s lens and retina. The vitreous cavity is the name of this space. The vitreous humor helps your eye keep its shape.

What is the purpose of aqueous humor and vitreous humor?

The aqueous humor flows in and out of the front of your eye. Its job is to keep proper ocular pressure (eye pressure) in your eye. The pressure is maintained by having the same amount of fluid come in as the amount of fluid leaving the front of your eye. This fluid fills the anterior and posterior chambers of your eye.

The vitreous humor provides nutrients to your eye and helps your eye keep its shape. It sticks to your retina at the back of your eye and lets light in. Your retina is the part of your eye that communicates with your brain so you can see.

Forensic scientists sometimes use the vitreous humor to find substances in a deceased body that aren’t expected to be there naturally.

Where are the aqueous humor and vitreous humor located?

Both the aqueous humor and the vitreous humor are parts of your eye.

Location of the aqueous humor

Your eye has an anterior chamber, which is the area between your lens and cornea. Your eye also has a posterior chamber, which is the area between your lens and iris, which is the colored part of your eye.

In the posterior chamber, the ciliary body makes aqueous humor. That fluid moves through your pupil to the front of your eye and then drains out of your eye into your bloodstream. It leaves your eye through the scleral venous sinus.

Location of the vitreous humor

The vitreous humor makes up the vitreous body located in the vitreous cavity between your lens and retina of your eye. The vitreous humor is contained in a protective layer called the vitreous membrane. Vitreous humor is more viscous than water but still lets light through. Vitreous humor is responsible for about 80% of the volume of your eye.

What are aqueous humor and vitreous humor made of?

Water makes up the majority of both vitreous humor and aqueous humor. Both are about 98% to 99% water.

Vitreous humor also contains salts, sugars, proteins and collagen in addition to water. There are also phagocytes, or cells that help keep your eye clean.

Along with water, aqueous humor also contains amino acids, electrolytes like sodium and potassium, ascorbic acid, glutathione and immunoglobulins.

What are the common conditions and disorders that affect the aqueous humor or the vitreous humor?

It’s important to have regular eye exams because finding any kind of condition early is best for treatments and outcomes.

There are several eye conditions that affect or relate to aqueous and vitreous humors, including:

• Glaucoma: Glaucoma refers to damage of the optic nerve, which an increased aqueous fluid build-up and high pressure in your eye causes. Glaucoma is the second-leading cause of blindness in the world.
• Posterior vitreous detachment: As people get older, their vitreous humor gets thinner and eventually loosens from their retinas. When this happens, you may experience flashes and floaters, which may be due to a posterior vitreous detachment. Some people may develop a retinal tear or detachment, so everyone who experiences new flashes and floaters should have their eyes examined.
• Uveitis: Uveitis refers to a group of diseases that cause red eye, eye pain and inflammation. It can affect your retina, uvea and sclera. The uvea is the part of the eye that contains the ciliary body. The ciliary body is involved in making the aqueous humor.
• Age-related macular degeneration (AMD): The changes in the vitreous humor as people get older can be a factor in AMD. This condition is the leading cause of vision loss in people older than 50. It affects their macula, the part of the retina that handles central vision.
• Macular hole: Holes in the macula happen because of trauma or because of another medical condition. It usually only happens in one eye. One treatment is a vitrectomy, which removes the vitreous humor and replaces it with another substance, like a gas.

What are common signs or symptoms of conditions involving the aqueous humor or vitreous humor?

Your ophthalmologist or other provider will ask about your medical history, family medical history and symptoms. These symptoms may include:

• Floaters and flashers.
• Low vision, blurred vision, halos around things you’re looking at and problems with side vision.
• Eye pain.
• Headaches.

What are common tests to check the health of the aqueous humor and vitreous humor?

Your eye care specialist will look carefully at your eyes during your eye exam. Your provider may use some or all of the following tests:

Eye charts and color tests

You’ve probably seen the eye chart before, which has letters on it. The size of the letters keeps getting smaller with every line. Your provider may also have a test using colored dots to see if you can see the difference between colors.

Visual field tests

These tests let your provider know how well your eyes move and how far you see to either side of you. Your eye care specialist will move their finger from side to side near your face and may move their finger closer or farther. You’ll only be moving your eyes. Your provider might use a computer for this test.

Tests that may require dilation

Your provider will put eye drops in your eyes that make your pupils get bigger (dilate). This makes it easier for them to see all the parts of your eyes. Your provider will use a handheld instrument to look into your eyes. This is called ophthalmoscopy or fundoscopy.

Your provider may also dilate your eyes to do fundus photography or optical coherence tomography to take images of your retinas and optic nerves.

Tonography

This type of test examines pressure in your eye. An instrument called a tonometer blows a puff of air onto your eye. Your provider may give you eye drops to numb your eyes if there will be contact. There is a method that doesn’t require any contact between the equipment and your eye.

What are common treatments for diseases involving the aqueous and vitreous humors?

Treatments for eye conditions that involve the aqueous humor or vitreous humor may include:

• Medications: These may be eye drops to reduce eye pressure or medications into your eye to stop new blood vessel formation.
• Laser therapy: This may be done to shrink blood vessels or repair your retina.
• Surgery: Your provider may suggest surgery to treat retinal tears or detachments. A vitrectomy is one of these surgeries.

What are ways to keep the aqueous humor and vitreous humor in my eyes healthy?

You can take steps to keep or improve your eye health. This should improve the health of your aqueous humor and vitreous humor. Tips include:

• Eat a healthy diet. Include green leafy vegetables, fruits and fish like salmon, tuna and halibut.
• Stop smoking. It’s not good for your eyes.
• Exercise. It’s good for you generally and can help keep you at a healthy weight. This improves your chances of avoiding getting diabetes and other conditions that may affect your sight.
• Get regular eye exams. Always let your provider know if you’re having any type of problem seeing.
• Wear eye protection, including your prescription glasses, sunglasses and protective glasses if you’re doing something that may harm your eyes.
• Follow the 20/20/20 rule if you spend a lot of time looking at computer, television and phone screens. This means you should look about 20 feet away for about 20 seconds every 20 minutes or so.

A note from Cleveland Clinic

Eyesight is important to most people. There are things you can do to keep your eyes healthy. This will affect even the parts of your eyes that are fluids: the aqueous humor and the vitreous humor. It’s important to have regular eye exams and report any changes in vision to your eye care provider. As with most types of medical issues, early discovery usually leads to better outcomes.