Main difference between conventional spherical lenses and aspheric is their convex surface. Aspheric convex surface allows to reduce the effect of aberrations in strong prescriptions, thus improving vision quality. As an example, an array of squares can be taken. Distortion with spheric and aspheric lenses is compared and big difference can be seen, which allows wearer to fell less fatigue.
Aspheric Lens (Thinner / Lighter / Flatter )
Besides that, flatter and thinner lenses can be produced. Noticeable effects on thickness, flatness and visual quality can be seen with prescriptions over -6.00 D or +4.00D. For strong prescriptions the choice of frames can also be a headache (due to front curve and thickness). With aspheric lenses the number of options for these patients is increased. People with strong minus or plus prescriptions also suffer from varying eye size effect (big or small eyes) as looking from other persons perspective. This unwanted side effect can also be reduced with aspheric lenses.
Main benefits include: