Which of the following statements is true about aspheric design in modern lenses?

• A. It only uses front-surface aspheric curves
• B. One or both surfaces can carry aspheric curves
• C. Aspheric curves are no longer used in progressive lenses
• D. Aspheric curves must be on the back surface

Answer: (B)

Aspheric design aims to reduce aberrations and improve optical performance by shaping lens surfaces away from a perfect sphere. In modern lenses, you can place aspheric contours on the front surface, the back surface, or on both surfaces. This flexibility lets designers minimize spherical aberration, enhance peripheral clarity, and create thinner, lighter lenses, especially in progressive additions where the geometry benefits from aspheric shaping. So, the idea that one or both surfaces can carry aspheric curves best captures how aspheric design is actually used. It’s not limited to the front surface, and progressive lenses still commonly use aspheric curves; there’s no requirement that they must be on the back surface.