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Vitreous Humor

What Is It, Location, Function, Most Important Facts, and More

Author: Ashley Mauldin, MSN, APRN, FNP-BC

Editors: Antonella Melani, MD, Ahaana Singh, Lisa Miklush, PhD, RN, CNS

Illustrator: Abbey Richard

What is vitreous humor?

The vitreous humor (also known as vitreous fluid) is a transparent, colorless, gel-like substance that fills the space between the lens and the retina within the eye. The vitreous humor is composed of mostly water, along with a small percentage of collagen, glycosaminoglycans (sugars), electrolytes (salts), and proteins.

Where is the vitreous humor located?

The human eye is divided into two segments, the anterior (front) segment and the posterior (back) segment. The vitreous humor is located in the posterior segment and fills the vitreous chamber, which takes up about 80% of the eye. The vitreous humor is not to be confused with the aqueous humor, which is a clear watery fluid that fills the anterior segment.

What is the function of the vitreous humor?

The vitreous humor’s main role is to maintain the round shape of the eye. The size and shape of the vitreous humor also ensures that it remains attached to the retina, which is the layer at the back of the eye that is sensitive to light. 

The vitreous humor is also a part of the eye that can help with vision clarity. Because the vitreous humor is a clear substance, light is able to pass through and reach the retina. Near the center of the retina is the macula, a pigmented region responsible for high-resolution color vision. When light travels through the vitreous humor to the retina and macula, it is then translated to visual information and transmitted by the optic nerve to the brain. 

The vitreous humor can also be helpful in absorbing any unexpected disturbances to the eye, such as a thump to the side of head. Absorbing the shock associated with the thump or similar disturbance can help prevent eye damage.

What happens to the vitreous humor over time?

With the normal process of aging, the vitreous humor may begin to shrink due to a decrease in viscosity or thickness. This process is called vitreous degeneration. As the fluid changes from a thick gel-like substance to a thinner liquid consistency, the vitreous humor separates from the retina. This can lead to vitreous floaters, or small disruptions in the visual field such as spots, web-like lines, or rings. No specific treatment is needed in most cases, as the floaters tend to become less noticeable over time. However, serious complications can occur, so it is recommended to consult a physician. 

In some cases, significant vitreous degeneration can lead to detachment of the vitreous humor from the retina, known as a posterior vitreous detachment (PVD). This can lead to flashes of light and a significant increase in floaters. PVD can also cause blood vessels to stretch and tear, potentially leading to a vitreous hemorrhage. Moreover, posterior vitreous detachment causes traction on the retina, which can lead to several complications such as a retinal tear, retinal detachment, or macular hole. 

A retinal tear can occur when the lining of the back of the eye (the retina) is torn as a result of the vitreous pulling away from the eye. If not treated promptly, a retinal tear can lead to retinal detachment, which is a medical emergency that requires surgery. Retinal detachment will typically present as photopsia (AKA flashes of light in the visual field), blurred vision, reduced peripheral vision, and the sudden appearance of a large number of floaters. If left untreated, retinal detachment can lead to permanent vision loss in the affected eye. In some cases, the macula can also tear when the vitreous pulls away from the retina, causing a small hole. A macular hole will usually result in blurred or distorted vision.

Can vitreous humor be replaced?

Vitreous humor can be replaced through a surgical procedure called vitrectomy. This treatment is reserved for those with vitreous degeneration who experience significant and persistent vitreous floaters, as well as those with complications, such as retinal tear, retinal detachment, or macular hole. In a vitrectomy, the vitreous fluid is removed in order to repair the tear, detachment, or hole. A gas bubble is first injected into the retina to flatten it, then a silicone oil is injected into the eye to replace the vitreous fluid.

What are the most important facts to know about vitreous humor?

The vitreous humor is a transparent, colorless, gel-like substance located in the posterior chamber of the eye. It helps maintain the round shape of the eye and can also help with vision clarity and shock absorbance. With aging, the vitreous humor undergoes vitreous degeneration, acquiring a thinner liquid consistency. This can lead to vitreous floaters, or small disruptions in the visual field such as spots. No specific treatment is needed in most cases, as the floaters tend to become less noticeable over time. A vitrectomy procedure may be performed for those who experience significant and persistent vitreous floaters, or for those with complications such as retinal tears or retinal detachment.

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