The best advice that I can provide is the following:
Frames
First and foremost, make sure that you choose a frame that gives you good coverage from the sun. When you use sunglasses, your pupils will be larger due to the lower levels of light reaching the eyes. However, if you have unfiltered sunlight entering your eyes (from above or from the sides), your larger pupils will increase exposure to harmful light rays.
But, remember that frames that are curved to hug the contour of your face, when filled with prescription lenses, may require some adaptation time.
Polarized lenses
Polarization cuts down the glare off the water, allowing you to see into the water. Performance of the polarization can be affected by the quality of the film and the alignment/rotation of the lenses within the frame.
At the US Open this year, Steve asked Chi and me to look at one of his polarized glasses. He was concerned that the polarization in one of his frames was not uniform. We noticed that the lenses were getting pinched within the frame. Lenses need to be cut slightly larger than the opening in the frames to prevent them from falling out. Consequently, lenses warp to various degrees due to their size relative to the frame. It’s unavoidable.
In Steve’s frame, the warpage created by this pinching effect appeared to affect mostly the alignment of the polarization film in the peripheral parts of the lenses: not ideal… but not a huge problem. Had the pinching affected the polarization of the lenses more centrally, we would have recommended him to have his doctor re-do them.
Anti-Reflective Coating (ARC)
For fishing, one of the most important purposes of an anti-reflective coating is to reduce reflections. It helps to decrease the amount of light reflecting off the back surface of the lenses into your eyes… mitigating glare.
All anti-reflective coatings are not the same, and there are several different types. Typically, the more you spend, the better the quality. Make sure that you purchase a multi-layer ARC that is hydrophobic and/or oleophobic.
Since ARCs are delicate coatings, most (if not all) premium anti-reflective coatings come with a scratch-resistant coating to protect them.
An ARC on the front is usually not recommended since it defeats an important purpose of sunglasses. By reducing reflections, an ARC increases the amount of light passing through the lenses and entering your eyes – making any tint effectively lighter.
Impact-Resistant Lens Material
For the most part, all fly fishers should get impact-resistant lenses: lenses that won’t shatter if struck by a rod, gaff, or heavy fly. In this category of lenses, there are two options: polycarbonate and Trivex. I recommend Trivex because it is optically superior (higher Abbe value) to polycarbonate.
Fortunately, both polycarbonate and Trivex provide UV protection. Many people do not know that UV protection is dictated by the material of your lenses and its coatings – not the darkness of your tint.
Tint
Polarized films are separate from tint. If you followed the discussion, what tint you should use is completely up to you. If you already use a particular tint and you think that it is awesome, continue to use it.
Copper tints have a logical basis for *young* people (and persons who have had cataract surgery) who fish. They transmit the long wavelengths (red) that water affects the most, and they filter out (diminish) the wavelengths that are least affected by water (blue). Moreover, they might be better during the early and late hours of the day when there is less light, and what light that is present is dominated by longer wavelengths.
For older fisherpersons who haven’t had cataract surgery, however, you want a tint that also transmits blue colors to compensate for the changes in the crystalline lens. Tints that transmit mostly red and blue wavelengths will appear magenta.
As for myself, I use a gray tint when I fish. It lowers the level of light for all wavelengths. Since the floor of rivers, the species (and hence colors) of trout, water levels, turbidity, etc are different throughout Northern California, I just want a tint that makes bright environments more comfortable without altering my color perceptions. Arguably, it’s the most versatile choice.
Level of Tint (Transmission)
When I was young (a long time ago), I could drive into an underground parking lot without removing my sunglasses. Nowadays, I must switch to a clear pair to find a parking spot – even with my headlights on.
One reason for needing more light as we age is cataracts. But, there is another aging change that decreases the amount of light reaching the light-sensitive tissue inside our eyes: decreasing pupil sizes. To give you an idea of the effect of cataracts and pupil size, the amount of light reaching the light-sensitive tissue inside our eyes is approximately three times less for a 60-year old compared to a 10-year old!
So, it’s no surprise that, as I get older, I find myself switching my sunglasses to a clear pair earlier in the evening as I fish. Pretty soon, I will need to bring a headlamp.
For older fisherpersons, it means that the level of tint (regardless of color) that is functional during the brightest time of day may be too dark in the morning or evening. A possible option to multiple sunglasses with more or less tint is a lens that turns dark with more light and eventually become clear as UV levels decrease. Some will even become *more* polarized as they turn darker.
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