A vitrectomy is a type of eye surgery to treat various problems with the retina and vitreous. During the surgery, your surgeon removes the vitreous and replaces it with another solution. The vitreous is a gel-like substance that fills the middle portion of your eye.

The retina is a layer of cells at the back of your eye. These cells use light to send visual information to your brain. Normally, the vitreous should be clear, so light can pass through your eye and reach your retina.