The vitreous is the jelly-like fluid in the main cavity of the eye. It influences the refraction of light as it hits the retina and supplies nutrients to the internal structures of the eye. In early childhood, the vitreous is clear. As we age, opacities form in the vitreous. These opacities are called floaters. Floaters are often visible when looking at a blue sky or snow. Some people are bothered by their floaters on a regular basis, while others manage to tune them out.
Flashers and Floaters
The vitreous is attached to the retina at distinct points. As we age, the vitreous can spontaneously break free from the retina. This process is called a vitreous detachment. When patients call in with complaints of sudden onset flashes and floaters, a vitreous detachment is one of the considerations (retinal detachment being the other and much worse). Floaters occur as the vitreous quality is changed and becomes more turbulent. Flashes occur as the vitreous tugs on the retinal tissue. This mechanical motion is interpreted as light by the brain. (The brain only knows to “sense” light when it receives signals from the retina.)
Below are before and after images of a patient with a vitreous adhesion. Note in the top image the arc shaped lines within the black void above the retina. The black void is the vitreous fluid (fluid is black in OCT images). The two arcs are outlines of the vitreous sack. In this upper image, the macula (central vision processing zone of the retina) is being tugged on by the vitreous (it has already detached at the points of the arc). At this point the patient is experiencing a partial vitreous detachment.
In the lower image, taken a year later, the vitreous has spontaneously broken free. A lucky result for the patient. If the vitreous continued to tug on the macula, this patient could have been at risk for the development of a macular hole (potential vision reduction to 20/400).