I have heard much about optical lenses, as I have been wearing reading glasses since 7 years ago, I know the general category of the glasses lenses, such as single vision, bifocal lenses, progressive lenses and multifocal lenses, last week, a friend told me that he wanted to buy aspheric lenses, he even didn’t know much about such lenses himself, just knew that they are more suitable for high prescription! So, any professional guys here know much about it?