The 2d thing is quite interesting. One of the things the examination showed is that I have poor depth perception. It is quite interesting when people point things:

- That before I go through a door I take an extra half step sideways to line myself up. I hadn't noticed I did it.

- I subconciously hold on to or reach out to touch them when I walk. Apparently I do this not only help me balance but also use it to test distance something I didn't realise I did.

- Animations of spirals, tunnels or high definition fly throughs put my brain into overload. This is down to my brain trying to work out the distance as the objects move the 2d / 3d conversion.

Like most things when someone whom know their stuff explains it to you at the right level it all seems so simple.