Wow that's a long old drive.
Perhaps a rest is in order?
DVLA should be informed of anything that might cause your driving to become impaired. If it's just the fact you need glasses, you don't need to inform them, but if it's something more dangerous, then yes, you do.
If you have an accident and it comes to light that you knew about your medical situation, and you hadn't informed them, you could be liable for far more than just a few points on your license.