Free-Form Digital lenses are the most important improvement in prescription sports eyewear, ever. We highly recommend digital prescription lenses in any frame, any prescription, every time. If you are getting a wrap style sports sunglasses, this digital design is even more important.
All of our Free-Form Digital lenses use the Shamir Autograph digital design. This is the best digital design in existence. The Essilor digital design is a very distant second place. Many labs have digital surfacing equipment but choose not to pay the licensing fees to use free form input. This is the equivalent of digitally recording your 8-track tapes. To see all the benefits of a digital lens you need true Free Form Digital input.
In a Free-Form Digital lens, your prescription is recalculated at every point on the lens.
This technology completely eliminates the "Fishbowl Effect" traditionally associated with putting prescriptions in wrap-style sunglasses.
A traditional prescription lens has the same curve all the way across the lens surface. For example, if your prescription is a -2.00 and you put this on an 8-base frame, the curve all the way across the back of the lens will be -10.00. this will produce perfect vision through the optical center of the lens, but as you look away from the center, this amount of correction will deteriorate. If you look through the peripheral portions of the lens, you are looking through a prism. This can create more distortion than correction.
In a Free-Form lens, your prescription is recalculated at every point on the lens. This computer-aided design produces sharp, clear vision throughout the entire lens. This technology completely eliminates the "Fishbowl Effect" traditionally associated with putting prescriptions in wrap-style sunglasses.
All Oakley True Digital lenses are surfaced with a free-form design that is based on this Shamir design. Kaenon Polarized, Costa del Mar and Serengeti also use a similar free-form design.
Free-Form Digital lenses are available in single vision or progressive. You cannot get a free-form bifocal lens. Patients with stronger prescriptions or a narrower PD measurement may have free-form lenses as their only option.
Quick Free-Form Lens illustration:
The best illustration of how a free-form lens is created was from someone who compared a lens blank to a sandbox. If we use the example above of a -2.00 lens on an 8-base frame, you could imagine your shoulder as the pivot point as you just scoop out a 10 diopter divot of sand to make a traditional lens. Now, to create a free-form lens in this imaginary sandbox, we would remove the sand one grain at a time to create a surface where every point in this sandbox (or lens) is directing light to the exact point on your retina where you need to create perfect vision.