Naked Science Forum
Life Sciences => Physiology & Medicine => Topic started by: thedoc on 01/03/2016 17:50:02
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Paul asked the Naked Scientists:
Hi Chris,
My question is, if sulphur hexafluoride is heavier than air, why was I not told to lie flat on my back looking upwards? I have read that face down is usual.
The background: I had an unsuccessful eye operation almost 2 months ago for a macular hole. The surgeon took out some of the fluid from my eye and replaced it with sulphur hexafluoride and I was told to lie face down for 24 hours a day for several days so that the pressure of the gas against the back of my eye would hold the "patch" in place until my eye healed .I noticed as the gas bubble got smaller, if my head was vertical and I looked straight ahead, that the bubble sank to the bottom of my eye. My son Aonghas also confirmed my suspicion that the gas was heavier than air by showing me a "magic " show on YouTube involving different gases.
I am reluctant to ask the English surgeon who has recently become a registration, lest he think I am being a smart aleck and he is less careful when he next operates on me for a second attempt, hopefully at the end of next month.
What do you think?
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I am reluctant to ask the English surgeon who has recently become a registration
Well whatever you decide... the peer-reviewed data clearly indicates that macular-hole surgery success rates are not contingent on posturing and/or non-posturing during post-op recovery.
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I believe that the purpose of the sulfur hexafluoride is to increase pressure within the eye. And it is the pressure, not the bubble, that holds the separated parts together to allow for healing. Where the bubble itself is has essentially no bearing on the pressure within the eye, as long as the bubble is inside the eye. I believe that SF6 is used because of how long it takes to dissipate (they can't just inject saline into your eye, and expect the pressure not to equalize over the course of a few hours...)