Phrase appears as early as 1830 according to OED.
During the Civil War that took place on the United States' soil, wounded soldiers battling with depression were given them as treatment. The theory was that the wearer would see things under a more positive light.(Can this(+) etymology be sourced?)
- Used other than with a figurative or idiomatic meaning: glasses that are tinted in a pink or rose shade.
- (idiomatic) An optimistic perception of something; a positive opinion; seeing something in a positive way, often thinking of it as better than it actually is.