Posterior Vitreous Detachment (PVD)
Posterior Vitreous Detachment (PVD)
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. These floaters appear as dots, circles or curly lines, which move in front of your vision and move as your eye moves. Depending on where a person is looking, he or she can mistake them for bugs or small rodents.
Most floaters and flashes will subside over time. Most patients’ symptoms fade over weeks to months, but some will occasionally notice the floaters indefinitely.
Retinal Tears
The vitreous can pull on the retina as it separates, stimulating the retina, which is perceived as flashes of light. Very rarely, the vitreous may tear a retinal blood vessel and cause a small bleed or hemorrhage, which is perceived as a shower of spots or floaters or haze. 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. This involves pressing on the peripheral retina, and thus the eye, called scleral depression. If a tear is found, your doctor can apply laser or freezing treatment (cryotherapy) to seal the rip in the retina.