If your lenses happen to be made of high index plastic (usually because of the desire for thinner lenses) the reflections per surface can be as high as 20% at larger angles, so an environment with bright lights will present you with “ghost images” on your lenses. This can be confusing and distracting under some conditions.

It can also obscure your eyes which is a disadvantage in face to face dealing with people. When they cannot see your eyes, they sometimes react by distancing themselves from you.

To overcome these issues, anti-reflection coatings can greatly reduce the reflection percentages (at some wavelengths). Since the coatings are wavelength sensitive, they tend to have reflections that are colored a dim green or some other color.