Period Costs. Period costs are expenses that are easier to attribute to times and accounting periods than actual production processes or finished goods. Typically, managerial accountant want to classify expenses in categories that can improve operations. Manufactures tend to focus on functional classifications.
The amber color of these impact-resistant polycarbonate lenses block short-wavelength blue light and 100% of ultraviolet (UV) light, thus providing additional protection against cataract formation and the development of macular degeneration, while increasing contrast on both sunny and bright hazy days.
Written answer: Although polycarbonate lenses will absorb almost all UV light without the addition of a coating, it will not absorb blue light, so you will need a tint or clip-on lens. The best colour for blue absorption is a yellow or amber tint but brown will also be nearly as effective.