Sunglasses. It sounds so simple. You know you need some shades when you’re out on the water in bright sunshine, but which ones are best? This is a question that pops up on online fishing forums on a regular basis. Most hardcore anglers have a favorite brand, style, and lens color. Many are also quick to recommend that others follow their choices, but can they explain why they’ve made those choices?
I thought I had a pretty good handle on the subject and felt pretty comfortable with my choice of eyewear. During a recent conversation a few points came up that I wasn’t sure about so I decided to do what we all do these days; I Googled it.
I started my research early in the evening and the next thing I knew it was 2:00 AM, and I was still reading. The internet never ceases to amaze me. The amount of information available on this subject was staggering. I felt by sharing some of this information it might help a few of my fellow anglers make more educated decisions when selecting their fishing glasses.
First, the scary part. We all know the dangers of UV (ultraviolet radiation) to our skin. It’s been hammered into our thick skulls for years and now I see even the most hard-headed of my friends covering up and lathering themselves with sunscreen. Who among us does not know a fellow fisherman who’s had a few suspicious moles removed or even lost a slice off the top of their ear.
However, not much has been said about the damage UV does to our eyes. There are myriad eye diseases including glaucoma, macular degeneration, and cancer that are thought to be directly related to UV radiation entering our eyes. On exceptionally bright days the amount of UV entering your eyes can cause photokeratitis, or simply put, a sunburn of the retina causing temporary and sometimes permanent blindness.
I read an interesting study that found UV exposure is at its peak in the early morning and late afternoon during certain times of the year. I always figured it was worse with the sun high overhead. According to the study, the amount of UV-B during these times was nearly twice that of the midday periods in spring, summer, and fall.
As an example, during the autumnal equinox, the greatest exposure was found to be at 9:00 am and between 2:00 and 3:00 pm. During winter the peak exposure moved back towards the middle of the day. This is something to keep in mind, not only for your eyes, but also for your skin.
Now for the good news. Sunglasses can be coated to prevent UV penetration into your eyes. The sun’s UV rays are grouped into three classifications based on their respective wavelengths and frequencies; UV-A, UV-B, and UV-C. We are mainly concerned with the first two as the UV-C rays are absorbed by our atmosphere and do not reach the earth’s surface. UV-B has been found to be the main culprit in causing eye disease. The effects of UV-A on our eyes has not been definitively quantified but it is important to make sure your lenses block UV.
This is easily done by purchasing sunglasses labeled as blocking “99 – 100% of UV light” or “UV absorption up to 400nm” which would be equal to 100%. Do not settle for anything less.
Also, the American National Standards Institute (ANSI) has provided a standard for non-prescriptive eyewear referred to as ANSI / Z80.3. If your glasses have the ANSI rating you can rest assured that they meet or exceed these minimum safety requirements. However, ANSI is a voluntary organization so it is possible that glasses meet the requirements without having the ANSI label.
The next thing to look for is the “polarized” label. Unfortunately not all sunglasses are, but there is a simple way to determine if your favorite pair really are polarized. But first, it helps to understand what the term means. The physics sites made my head spin but I think I’ve managed to boil it down to this. Sunlight is an electromagnetic wave with electric and magnetic vibrations occurring in multiple planes. This is referred to as unpolarized light, meaning it is vibrating in a variety of directions.
There are several ways in which light becomes polarized. What we are concerned with is polarized light caused by reflection. When the unpolarized light strikes a non-metallic surface, such as water, a percentage of the waves become polarized along a horizontal plane. The angle at which the light strikes the water’s surface determines the degree to which the vibrations become polarized. The lower the sun’s angle the greater the reflection, or glare. We see the reflection as white glare when the intensity of the light is above the level our eyes can absorb. Light is measured in lumens. Average indoor light is around 500 lumens. In the shade it is around 1000 lumens. We start to get uncomfortable around 3500 lumens and see white glare when the level reaches 4000. Again, depending on the sun’s angle, we’re looking at upwards of 6000 lumens when looking at the glare on the surface of the water. Prolonged exposure above 10,000 lumens can cause temporary or permanent blindness.
The magic of polarized sunglasses occurs because they have a layer of vertically oriented long-chain molecules applied to the lens. These molecules completely block out any light waves that are perpendicular to their alignment, thus the horizontally polarized glare is erased. Other light waves are allowed to pass through as visible light. Perfectly vertical light waves pass through at full strength while other angles pass through at varying degrees. Polarized lenses will be most effective when the sun is between 30° and 60° above the horizon with 37° being the absolute optimum. Keep in mind that we are talking about flat water. Ripples and waves will change the angles of light wave polarization and thus change the effectiveness of your glasses.
Now, don’t you just feel all educated?
So, if you want to know whether your sunglasses are polarized you need to perform a simple test. Hold your glasses in front of you, aligned as if you were wearing them, and look at the glare on the water or any other non-metallic horizontal surface. The glare should be mostly blocked.
Slowly rotate the glasses and watch what happens to the glare. If you have polarized lenses the glare and brightness should increase and max out when the glasses are perpendicular to the glare-producing surface. If you notice no change then they are not polarized and they’re not doing you any good out on the water. It might also explain why your buddy always sees the fish before you do.Next month we’ll take a look at the features you need to consider when narrowing down your choices. Until then, get out there and enjoy the warming tides of spring.