human
I'm a little confused about the different types of eyeglass lenses.
assistant
The most common type of lens is an optical lens, which corrects vision and can be used for both near and far vision. Another type of lens is an anti-reflective coating, which helps reduce glare from bright light sources and improves contrast. A third type of lens is a photochromic lens, which darkens in bright sunlight and lightens when it's darker.