What Is 'Base Curve' For Lenses in Sunglasses and Glasses Frames?

What is a 'base curve' or a 'lens curve'?

Often when looking at lenses, you will notice descriptions mentioning a 'base curve'. The more generic term is 'lens curve'. But what does base curve mean? 

The base curve or lens curve refers to the projection of the lens curve at its highest point. While some glasses come with a flat lens or '0 base curve', others come as a 2 base curve, 4 base curve, 6 base curve, even 8 or 10 base curves for very wrap-around effects. 

The flash effects are usually best seen with zero base curve or 2-4 base curves, however any lens curve will show the flash as you move. The reason a lens curve was created, was to fit different styles of eyewear frames, to create different looks. They were also created to give more coverage of the eyes while wearing certain types of sunglasses. 

While some visual distortion may appear if one wears too-high a base curve with visual lenses, for sunglasses, the larger the curve, the more of the eye is covered from the elements, generally. Some examples below will help you to understand the differences.

lens curve showing curvature of sunglasses lens curve

Vintage Eyewear has selected certain lens styles in certain colors, to accentuate the look, showing the colors and flashes off to their best potential. Please contact us if you have any questions about lens base curve, or which lens is best for you. 

lens curvature showing curve of sunglasses lens curves