It turns out your prescription can improve. I always assumed it was just an inevitable downhill progression but, no, my eyesight has actually improved marginally over the last five years. Turns out this isn't uncommon, though it usually happens with people in their forties or fifties, that the ageing process of your eyes can even out deformities.
They took pictures of the inside of my eyes and showed them to me. They wouldn't let me have copies, though, but it looks kind of like a red lava lamp made out of skin.
I had a nice chat with the opticians who did my tests, we discussed the purpose of various machines they used on me. There was an almost arcade machine thing where I pressed a button every time I saw a light flash that was testing my field of vision. The only one they didn't want to discuss was the one that blows a really cold, really intense puff of air into your open eye so I'm beginning to think that one actually serves no purpose and just gives them a sense of power as they force you to go through it again and again and again.
Just a thought, that last one.
Of course, any time I get new glasses I feel the need to dig out this Peanuts strip (sadly this is the best version I can find through Google):
I tell you what though: going from round frames to square does odd things to your peripheral vision. Its like someone's been messing with the field of view slider.