Thinner and lighter high-index lens materials have made the world of eyeglasses very different
How do they work? Glasses correct your vision by bending the light that passes through to your eyes. The stronger your prescription, the more the light needs to bend. This generally means a thick lens, but not with a high index lens that bends light through less thickness.
What are the benefits? A thinner, flatter high-index lens provides the same strength of correction as a thicker standard lens. That means people who are very short-sighted can avoid extra-thick lenses that make their eyes look unnaturally small; long-sighted people can avoid lenses that make their eyes look exceptionally large.