More seriously, though, I am not far-sighted. I do not need corrective lenses to read books, newsprint, magazines, or labels at the grocery store despite the possible genetic predisposition baed on the need for reading glasses by my parents and siblings. I often have to read very fine details on nautical charts, sometimes in a seaway, sometimes at night with the use of a headlamp.

Exhaustion definitely changes my eyesight. I'm coming off of two days of kayaking and camping with high school kids followed by an intensive four hour lesson teaching rescues. (Imagine ~3600 boat-poses per hour, then subtract a few hundred and replace them with pulling swamped boats out of the water and across my lap to empty them, climbing out of the water and into the boat to demonstrate a dozen types of self-rescue.) I tried to read last night but my eyes could not focus; I vaguely remember making my way toward bed but woke up twelve hours later downstairs on the floor.

I call it "wisdom". :-)