When you have vitrectomy surgery on your eye the eye surgeon will use a gas bubble in your eye to allow the retina to heal by covering it.
The surgeon creates the gas bubble for retina healing purposes and later on the gas bubble will eventually go away.
The gas bubble in your eye is injected into the vitreous space inside your eye in combination with laser surgery or cryotherapy.
The gas bubble that the surgeon injects into your eye pushes the retinal tear into place against the back wall of the eye.
The gas bubble is normal and will eventually go away on it's own after the eye surgery.