I've had the same glasses prescription for the better part of a decade, and it's time I get my eyes checked to see if it's still applicable. This idea was prompted by the fact that I can't for the life of me ignore the permanent smudges and smears that have formed over my lenses with age. That said, I know a lot of people who never clean their glasses and have noticeable fingerprint marks all over their lenses. They can go about their business without a second thought to the filth that obstructs their vision, why can't I?
This idea then segues into the second question that I often ask: why do so few people notice the differences between standard definition and high definition screens when looking at text on a screen all day?