For sunglasses, I stick with glass lenses with high quality anti-reflective coatings, for example, brands like Revo sunglasses.
Except that on a bicycle, there is the danger of an impact shattering even shatter resistant glass lenses (e.g., a chunk of gravel at 40 mph), making the choice of polycarbonate or similar materials a smart move for biking.
In the past, I’ve had disappointing experiences with polycarbonate lenses, and go figure I just bought a pair of Oakley’s top-of-the-line sunglasses for about $200, and they show the same problems I’ve seen five years ago: internal reflections that create a faint double image.
Now I’m very sensitive to these things as a photographer, and you might not be. But here are the facts of what I found, and how I feel about it.
At right is the full moon, shot through one lens of an Oakley polarized sunglass.
There is one double image, but when actually wearing them, there are two double images plus the main actual moon itself— one bright white moon and two orange ones that orbit the moon wildly as one’s angle of view changes, a confusing and disorienting effect at night with headlights and street lamps, etc, should one be wearing an appropriate clear lens for night-time eye protection as I do.
Now it’s not like I howl at the moon on a regular basis while wearing my sunglasses , BUT this double image also subtly degrades EVERYTHING by overlapping bright details onto other details nearby. Contrast and resolution are thus less than ideal, which could cause subtle eyestrain over time.
I checked my Maui Jim sunglasses that have some kind of non-glass lens (probably polycarbonate, and they do have an anti-reflection coating), and they do not exhibit this issue. So it’s my conclusion that Oakley is using less than top grade optics, and this I deem unsuitable for my personal use. I will be looking into other options, such as Revo Redpoint, which has a “Serilium” lens, whatever that is (it’s not glass).
Update: I just received two pairs of Revo Redpoint sunglasses with Serilium lenses (non glass). They have anti-reflective coatings inside, and appear to perform very similarly to top-notch glass lens Revo sunglasses. When the sun and moon cooperate, I will provide my assessment.