NEW YORK (AP) — When I was 13, I was sent to the optician for the first time, and came home with glasses. Suddenly, the world was sharp all around me. I was surprised by the crisp lines of the tree branches against the sky. It was news to me that I was near-sighted, because I had been used to seeing the world in a blur.

Apple Inc. sells a similar epiphany, starting this week, in the shape of a notebook computer. One of its new MacBook Pro models has a “Retina” display, a screen that packs four times as many pixels as a standard display.