I had my 2nd surgery for retinal detachment (vitrectomy) 4 weeks ago and the dr said she put in a big gas bubble. I saw the dr last week and she said the bubble was half way down and i would only need to position my head down about half a day rather than 24 hours a day. When will i be able to look up all day? It looks like the bubble is more than half down. She said not to sleep on my back until the bubble is completely gone but she didnt say when I can start keeping my head up all day.