A clear, jelly-like substance called the vitreous fills 80% of the inside of the eye, in the space behind the iris and lens. The vitreous fills the space behind the iris and lens. It lies between the lens and the retina.
It is typically tightly attached to the retina. As we age, the vitreous becomes more liquid-like and separates from the retina near the back of the eye, over the macula. This separation is called a posterior vitreous detachment, or PVD. A PVD naturally occurs in 40% of people by age 40 and nearly 70% by age 70; however, it can occur in younger nearsighted patients or after an eye injury or surgery. As the vitreous separates from the retina one will often see floaters.
Most floaters and flashes will subside over time. Most patients’ symptoms fade over weeks to months, but some will occasionally notice the floaters indefinitely.
The jelly-like fluid in the posterior chamber, called the vitreous, is surrounded by a very thin membrane. The fluid also contains many fibers that are usually invisible. This whole structure is called the vitreous body.
Sometimes the fibers in the vitreous body pull loose from where they are normally attached. When this happens, they can make cast shadows inside the eye.
Very rarely, a floater turns out to be blood tugging on the blood vessels. This could be caused by an injury or by systemic conditions that the patient may have. When there is bleeding, there is a greater danger of losing vision.
More often, floaters are caused by a posterior vitreous detachment. This occurs when the jelly-like fluid in the eye liquefies with age.
The vitreous can pull on the retina as it separates, stimulating the retina, which is perceived as flashes of light. If the vitreous rips the retina, this retinal tear will allow liquid vitreous to fall behind the retina. As the fluid falls behind the retina, the retina separates from the back of the eye. The retina begins to lose its function and this is perceived as a curtain or veil over the vision. This is called a retinal detachment.
Your doctor will try to find the retinal tear before a retinal detachment develops. The examination involves dilating the pupil and looking at the vitreous and retina.
The symptoms described above may not necessarily mean that you have a detached retina. However, if you experience one or more of these symptoms, contact our office for a complete exam.