I know many people who suffer from hypoglycemia, and some
who even will completely pass out if glucose gets low. That
is rare, for in most cases,
the person feels crummy for a while, but the body eventually regulates the sugar levels. During a hypo episode (as a type 1 diabetic, of course I have occasionally overdosed by accident when my insulin didn't properly match the food carbs I ate), the eyes feel dry and vision CAN change temporarily.