Which statement best describes the effect of aspheric design on edge performance?

• A. Reduces edge distortion and aberrations
• B. Increases edge magnification
• C. Increases spherical aberration
• D. No effect on edge performance

Answer: (A)

Aspheric design changes the lens surface from a constant-radius sphere to a shape that varies toward the edge, so marginal rays are guided to focus more in line with central rays. This compensates for spherical aberration that occurs with a spherical surface, where edge rays focus differently than center rays. By tailoring the curvature toward the periphery, the lens reduces edge distortion and other peripheral aberrations, yielding clearer, more uniform vision at the edges. That’s why it best describes the effect: a smoother, less distorted edge performance. Increasing edge magnification or worsening spherical aberration would contradict how aspheric profiles are intended to improve peripheral optics, and saying there’s no effect ignores the perceptible improvement in the lens edge.