Yeah, I have craptacular uncorrected vision also, which makes even that screen almost useless unless the chumby was sitting right at eye level by my face (which it isn't). I was thinking you (or maybe me once I learn the device better) do something that would be help all but the most blind of us, and realize we can leverage a color screen to help us out. First lets just say we need to know the time in the morning when we are without our glasses/contacts. Second. Assume we only need to know the Hours and Minutes. I was thinking you could have the entire back of the screen (or the color of the digits) indicate the hours. And just display the minutes taking up almost the entire screen.
So something like this (colors are just an example)
Black background = Midnight to < 4 am
Blue background = 5 am
Green background = 6 am
Red background = 7 am
Purple background = 8 am.
White background = 9+ am.
Sure you would have to memorize the colors that indicate the hours, but that would mean with even the quickest glance I would know the hour, and if I squinted the minutes.
Ok, my vision really blows but I can still tell colors from a good distance without my glasses, so another option might be to forget minutes all together:
Before I need to be out of bed: black
Time to get out of bed: white
Late for work by this time: red
And I could have the colors fade from one to the other. So when I see it getting pink, I know I need to get up. Or, just have 10 colors, one for each digit and just have 4 big blocks of colors (that might be hideous).
Since this device is programmable, we could have it go back to a "normal" clock at some time where it is highly likely that we're capable of seeing it. So this mode, could switch to a more accurate time piece at some time. At say midnight it could switch to our color mode.