FLT Sunglasses Surpass ANSI Spec in Test

Following the debut of its mineral glass SKY lens in 2017, Method Seven introduces a synthetic pilot lens that shows unparalleled clarity in laboratory testing. Constructed from a durable polymer with dual high-quality coatings, the new FLT series pilot sunglasses are a non-polarized solution for pilots seeking next-level performance in a synthetic lens. Barry Shiller, Chief Technology Officer of M7 Labs, explains the scientific details behind the test results and what they mean for pilots.

Overview

Though synthetic lenses are lightweight and durable, most brands sacrifice the supreme visual clarity provided by crystalline lenses. This is because synthetic lenses are manufactured with dyes and molds that vary in quality and design. Non-dissolved dyes and imperfections in the lens can deflect light and cause blurring. As pilots stake their lives (and often, the lives of others) on visual precision, they cannot tolerate blur or distortion of their natural vision.

Methods

COLT Laboratories tested the FLT lenses for corrective powers and haze, using the Method Seven Altitude Wrap FLT Sunglasses. The results were compared with American National Standards Institute (ANSI) Specifications for non-corrective lenses intended for attenuation of light, commonly known as sunglasses.

Three corrective powers were tested: refractive, astigmatic, and horizontal prism. Refraction measures the magnification of a lens. Astigmatism quantifies the change in power as seen across the field of vision. Horizontal prism measures the ability of each eye to register the same image and is particularly important in lenses with curvature—poor design can cause distortion in the periphery from unwanted prism effect. Many pilots can detect a horizontal prism of as low as 0.15 diopters, and almost all suffer distorted vision at 0.25 diopters or greater.

Haze testing measures the percentage of collimated light that gets deflected by more than 2.5 degrees. Imperfections in the lens and non-dissolved dyes can cause such deflections.

Results

Table 1. FLT Sunglasses exceed ANSI specifications for haze, refractive power, astigmatic power, and horizontal prism.

Conclusions

“Most high-quality aviator glasses have a haze of between 0.2% to 0.7%,” notes Shiller. “At a maximum haze of less than 0.2%, the M7 FLT lens is the clearest synthetic lens available to pilots.”

Ideally, non-prescription pilot lenses should have refractive and astigmatic powers as close to zero as possible. At 0.02 diopters for refractive and 0.05 diopters for astigmatic power tests, “M7 FLT lenses are closer to this goal than almost all other pilot lenses on the market,” claims Shiller.

Minimizing the horizontal prism effect in a wrap-around frame has historically presented a challenge for lens companies. According to Shiller, “most quality manufacturers settle for a horizontal prism of 0.25 diopters or less.” However, the Altitude Wrap FLT Sunglasses returned an extraordinary result for horizontal prism: 0.05 diopters—one-tenth the ANSI specifications—setting a new bar for peripheral vision.

“You don’t get any distortion when you look through the lens,” says Shiller. And since the FLT lenses are non-polarized, pilots can see through windscreens and view instrument panels with excellent clarity. Lightweight and shatterproof, the new FLT pilot sunglasses offer Method Seven’s classic notch filtering technology in a lightweight and shatterproof synthetic lens. “We love geeking out on this kind of stuff,” admits Shiller. “To see this lens come to fruition and have it surpass every test is immensely rewarding.”