For the past few months, I have been working many hours a day on the italic version of a sans I began 10 years ago. To compare, I revisited the upright version just now to find my eyes had gotten so accustomed to the italic slant, that the upright now looked back-slanted in a bizarre way. This has happened to me several times before but it had always corrected itself quite quickly. I have always been the type of designer to trust my eyes more than grid lines or arithmetic so this presents a problem. How do I know when I am seeing "normal" again? Does this distorted slant-o-vision worsen with age? I would be curious to hear from both young and old of their experience with this phenomenon.