During a vitrectomy, the surgeon will remove part of the vitreous substance to prevent it from tearing or pulling the retina any further. Most of the time, an air bubble is inserted to take the place of the removed vitreous substance after surgery.
When post surgery patients keep their face down, the air bubble rises to the back of the eye, where it presses the retina flat so it can heal. Holding this position is sometimes referred to as posturing. Vitrectomy recovery equipment such as that rented by FaceDown Rental makes posturing comfortable for the patient.