. >> and astronaut barratt is joining us from the space station at nasa.let me ask you, first of all, how are your eyes now? have they stayed affected about your trip? >> well, yes, they have, pretty much. i spent 199 days in space in 2009 and landed in october of that year. the vision changes that we noticed have been pretty static since then. so, again, what it is is a far sighted shift. if you wear the right corrective lenses, it's totally functional. >> when people's pressure comes down, often times their vision improves but in their case it didn't happen. something else that was striking, it was just in men. and correct me if i'm wrong. you're a doctor, you're studying this. any idea as to why that is? >> well, you have to think of some of the obvious things, perhaps there's a hormonal protection of the vascular system. i think much of this is related to the shifts that happen with zero gravity. and certainly the vascular system of females is influenced by higher levels of hormones that might differentiate us. another thing is, there are changes that