Bi-aspheric Myopia lens

Usual Aspheric design: curve radius becomes steeper from center to edge on first surface of lens

Bi-aspheric design: Curve radius becomes flatter from center to edge on both surface of lens

Fluorescent lamp image on lens’s first surface comparison between an aspheric lens and a bi-aspheric lens

　　　　　　　　　spheric　　　　　　　　　　　　　　　　　　　　Bi-aspheric