How to chooe the index and lenses?
The refractive index of the lens represents the thickness of the lens, which is the result of different refraction produced by different light-transmitting substances. The thinner the lens is not the better, the suitable one is the best.
1.56 index: -0.00 to -4.50 ,or +0.00-+4.00
1.61 index: -4.50 to -6.00,or +4.00 to +6.00
1.67 index:-6.00 to -8.00 ,or >+6.00
Clear prescription:Transparent coated lens, hardened and anti-fouling treatment, can not change color, can block some harmful light, but does not have the function of preventing blue light.If you just want reading glasses lenses,you also should choose this option.
Transiton:When you are outdoors and exposed to ultraviolet rays, the lenses will turn dark, usually in gray and brown, gray is the best choice, darker and faster.Special Note: It will not change color in the car, because the car glass can block most of the ultraviolet rays.The photochromic lenses we provide are not famous brands, but they are very cost-effective and can usually be used for 2-3 years.
Progressive：When you can not read well ,and don't want to take off and put on my glasses repeatedly,progressive lenses is your best choise,you can read and drive use same glasses.
Prescripiton sunglasses:For long-term outdoor activities, you will need a pair of prescription sunglasses, which are much darker than transiton glasses, which can effectively filter light waves and make you feel comfortable, but please note that dark colors do not filter ultraviolet rays, this is a misunderstanding, the material of the lens Blocking UV rays, resin is better than glass.Dark gray won't change any color, just darker, but dark brown will warm things up.