Double aspheric lenses explained

If you have a strong prescription, you can avoid the dreaded 'milk bottle look' by choosing the right type of lenses.

Better still, your eyes will look their natural size instead of being magnified smaller or bigger than they actually are.


What are double aspheric lenses?


Double aspheric lenses use irregular curvatures on both their front and rear surfaces to make them thinner in profile, lighter in weight and aesthetically flatter. These lenses are popular for strong prescriptions to reduce thickness at their centres or edges.


For ease, here’s a handy breakdown of each lens profile;

  • Spheric lenses use a singular curvature on their front and rear surfaces
  • Aspheric lenses use an irregular curvature on their front surface
  • Double aspheric lenses use irregular curvature on their front and rear surfaces

      This design makes double aspheric lenses flatter, thinner and sleeker in your frame. (See the illustration below.)


      Illustration of a spherical, aspherical and double aspherical spectacle lens profile


      What prescription type do double aspheric lenses benefit most?

      Double aspheric lenses are especially beneficial for strong plus (+) prescriptions with Sphere powers of more than +6.00. Due to their curvatures on both the front and rear surfaces, they reduce lens thickness at the centre of the lens and thus the overall weight. 

      • If you’re strongly farsighted (+) double aspheric lenses will reduce lens-bulk in the centres of your lenses due to their convex profile.
      • If you’re strongly nearsighted (-) double aspheric lenses will reduce lens-bulk at the outer edges of your lenses due to their concave profile.

      See the illustration below.


      Illustration comparison of spheric and double aspheric spectacle lenses


      Are aspheric lenses better?

      Aspheric or double aspheric lenses have the advantage of being thinner, flatter and lighter weight than traditional spheric equivalents. This makes them easier to wear in your glasses frame with improved aesthetics due to their sleeker appearance.


      Why are high index lenses so expensive?

      High index lenses are more efficient at refracting (bending) light, therefore require more costly (high index) materials to manufacture. Furthermore, they require finer tolerances of accuracy which adds to their higher production costs. For a guide to high index lenses, check out my other blog here.


      Are double aspheric lenses worth it?

      Double aspheric lenses are certainly worth it if you have a strong prescription and seek thin, lightweight lenses. Not only do they look better in your frame, but they prevent 'milk bottle' magnification which makes your eyes look bigger than they really are. If you prefer very thin spectacles, double aspheric lenses helps reduce overall bulk.


      Key takeaways

      Double aspheric lenses are;

      • Less distorted at their edges
      • Provide a larger field of view
      • Irregularly curved on their front and rear surfaces
      • Usually made in high indexes such as 1.67 or 1.76
      • 30-40% more expensive than single aspheric equivalents
      • Thinner, flatter and lighter weight than spheric or single aspheric equivalents
      • Required anti-glare and anti-scratch coatings
      • Can be tinted as sun lenses

      Hopefully you found this article helpful. Please check out our other eyecare blogs. Thanks for stopping by.

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