Rush seems to have the Daniel Jackson syndrome when it comes to the wearing of glasses. In early episodes he is occasionally seen struggling to read his own notes by holding his broken glasses over the notebook. In Episode 9, Earth, he MacGuyvers a new arm for his specs and comments how much better his vision is. However, both before and after that episode we frequently see him looking through his notes without his glasses and apparently with no difficulty.

I suppose it's possible that - like me - he only needs reading glasses when the print/writing is small or illegible, or when his eyes are tired. But in Air he's wearing his glasses a lot of the time while on Icarus, and is using them to look at people as well as at writing. I suspect we may be back to the writers' idea that smart people have to wear glasses to look smart * but then they keep forgetting to include a mention of the specs in the script, and so the props people don't bring them to the set.

* Did David Hewlett refuse to wear glasses? ;-)

The episode Human finally answers a question that had been puzzling me for a while: why wasn't Rush part of the Atlantis expedition if he's so smart and so knowledgeable in Ancient? However, this episode establishes that he was only brought into the Stargate programme when the Icarus Project was set up two and a half years ago.

Yeah, this episode did give us a glimpse into his background.