If you've had a pneumatic retinopexy, which is an office procedure to repair a retinal detachment, you need to position your head properly so the bubble in your eye will seal the retinal break(s) causing your retinal detachment. By sealing the retinal break, the gas bubble prevents fluid from inside of your eye from passing through the break and under the retina. That allows the natural pump under the retina to pump the fluid out from the subretinal space thus reattaching the retina. A gas bubble injected into the eye in the office is relatively small. Usually the bubble initially fills about 10% of the vitreous cavity. The two gasses used for pneumatic retinopexy are sulfur hexafluoride (SF6) and perfluoropropane (C3F8). An SF6 bubble grows within about 2 days to twice its original size and then begins to slowly shrink being totally absorbed within about one or two weeks. A C3F8 bubble grows in 2 days to about 4 times its original size and then begins to slowly shrink being totally absorbed within about 4 weeks. So the maximal bubble size in and eye after pneumatic retinopexy is about 30% to 40%. A bubble that size covers about 3 clock hours or 90 degrees or 1/4th of the peripheral retina. That means if you are positioning exactly as you should, or within about 1 clock hour of where you should, the gas bubble is properly positioned against your retinal break.
Because gas bubbles rise you need to position your head tilted in such a way that the retinal break in the back of the eye is as high as possible. For example, if you have a retinal break in either eye at 12 O'clock, sitting up straight, will put the bubble at 12 0'clock against the break. If you have a break in either eye on the right side of the retina (from your perspective) you would lie on your left side, so the bubble would float up inside your eye and seal the break. Then you need your eye also to be looking in the proper direction which is usually straight ahead or a little bit down (down always means toward the center of the earth). Watching television is great for your eye after pneumatic retinopexy if your TV is at eye level or a little bit below. Sitting in a recliner is bad for your eye after pneumatic retinopexy because when you are reclining, with your head laying back staring at the ceiling, the bubble will roll to the front of your eye, behind your lens, and do nothing for your retina. In that position, the retinal procedure won't work and the retina will not reattach.
You should try to position 90% of the time day and night. If you are lying on your side, you should put pillows around yourself to keep yourself from rolling around at night. If you are sitting up, sleeping can be difficult and is best done like you would sitting in a seat on an airplane, with only a slight tilt backwards to support your head.
After any retinal detachment procedure, for about 2 weeks, you should avoid jarring or vibrating activities. Reading, with constant back and forth motion of the eye, is hard on the retina and should be minimized immediately after retinal detachment repair. Other activities to avoid for two weeks after retinal detachment repair include yard work with vibrating machines, sitting in a vibrating massage chair, riding on a bumpy vehicle like a motoboat, jogging, and jumping rope. Usually it is OK to engage in gentle activity like walking or biking, as long as you are able to maintain your proper head position during the activity. Generally watching TV is the best. Before modern surgical techniques were available, patients with retinal detachment were placed on prolonged and complete bedrest. The retina sometimes will reattach after 6 weeks of total bedrest (but doesn't usually stay attached).