lumen to lux and back

[Jimmyjazz]

I know lux is lumens hitting a square metre, so you can't directly convert them.
I'm shopping for light therapy devices, and half the time they are described in lux and half the time in lumens. I don't know why they would use lux as eyeballs aren't square metres in size.
I've read using a 10,000 lux light source for 30 mins is recommended. I have light bulbs that are 700 lumens and 1740 lumens. Can someone please help with converting this?

and I don't understand how they can say 10,000 lux without giving a distance. is that square metre next to the light or a room away? argh

Would it make sense to day that the pupils combine to about a cm squared, so 1/10000th of the # of luxes is how many lumens get in your eyes?

[ergognome]

I realize that the original post was over a year ago but my answer may help with part of the question. Lux are useful because they describe the amount of light falling on an area, [b]at that area[/b]. So if I, as an ergonomist, want to check that a desk has enough light to read documents I will measure the light at the desk with a lux-meter. Knowing the light intensity at the source is only partly helpful, as the useful light is dependent upon the distance you are away from the source.