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What is EPF (Eye Protection Factor)?

By R. Kayne
Updated Mar 03, 2024
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The Eye Protection Factor (EPF) is a scientifically applied solar rating designed to help people compare the efficiency of sunglasses in protecting the eyes from the harmful effects of radiation. EPF is to non-prescription sunglasses what the Sun Protection Factor (SPF) is to sunscreen. The EPF rating is based on frame coverage, ultra-violet (UV) protection, blue light protection and infrared protection, or the ability to shield the eyes from heat. The final EPF rating is a result of averaging the scores of these four factors known by the acronym FUBI:

  • Frame coverage
  • UV protection
  • Blue light protection
  • Infrared protection

Frame coverage is an important factor, as light that can reach the eye without passing through the lenses increases exposure. UV rays can cause sunburn and skin cancer, but they can also burn the eyes, resulting in cataracts and other visual problems. Recent research indicates that blue light, or high energy visible (HEV) light, might contribute to macular degeneration, or loss of vision detail. Protection from infrared was included as part of the EPF rating because the eye purportedly processes lightwaves differently if the surface of the eye increases in temperature. This isn't usually an issue unless an individual works in close proximity to a heat source, such as a blower's torch.

In averaging the overall EPF rating (~70-100), more weight is given to UV protection than to blue light protection, as UV rays are more damaging. Accordingly, the blue light rating carries more weight than the infrared rating. Sunglasses that have a final EPF rating in the mid to upper nineties have scored well.

The FUBI EPF website lists tested sunglasses along with their EPF scores. Though voluntary, some hope this standard becomes as widely adopted as the SPF standard. The most recent non-prescription sunglass standard to be adopted in the US was the American National Standards Institute (ANSI) Z80.3-2001. This 2001 standard does not require sunglasses to quantify how much UV light is blocked, nor does it require a test for transmittance of blue light. It also does not take frame coverage into consideration.

Sunglasses made in accordance with ANSI Z80.3-2001 are not necessarily adequate, unless they significantly exceed it. The EPF rating provides more information to consumers, allowing wiser choices to be made based on quantitative scientific testing methods.

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Discussion Comments
By Charred — On Oct 28, 2011

@nony - Knowing the rating for EPF is certainly useful in choosing the right sunglasses.

Honestly, I don’t think I’ve even ever looked at ratings or things like that before when buying sunglasses. However, the new photometric lenses out on the market may spare you some hassle in my opinion.

These are lenses that adjust to the intensity of the sun’s light, and protect you from all of its harmful radiation. I think this would be the ideal path to take for someone who is not sure what kind of sunglasses to buy based on the rating system described here.

By nony — On Oct 28, 2011

@miriam98 - I think that UV light is not only more powerful than other kinds of light, but more dangerous too. That’s because it’s invisible.

You hear people telling you that you should never look at the sun during an eclipse. People are tempted to do that, because of course during an eclipse, the sun is blocked out.

However, there are still ultraviolet light rays which can burn your retina if you stare at the sun. Is an eclipse really that exciting that you want to risk that?

I would recommend that you at least have no less than a UV filter and sunglasses on, or better yet, don’t even bother looking at the sun directly. Unless you’re a professional, wait until the photographs come out and hit the Internet. It’s not worth it to look at the sun in my opinion, regardless of the time of day or the phenomena involved.

By miriam98 — On Oct 27, 2011

I went to the eye doctor to get an eye exam and order a new prescription for my eyeglasses. They conducted a series of tests and everything turned out okay.

However, they put these fluids in my eyes to dilate them as part of the tests. As a result, they told me my eyes would be sensitive to the sun light for a few hours.

So on my way out they gave me these eye shades that just slip over the front of my glasses, to wear as I drove back home. I was able to carry on indoors just fine without the glasses. As an experiment I stepped out into the sun without the shades - the light was almost blinding.

I shouldn’t have stepped outside I guess but I wanted to see how long the dilation lasted. Our eyes are very sensitive indeed to sunlight.

By LisaLou — On Oct 27, 2011

It is good to know the possible dangers that sunlight can be to our vision. Much like sun damage to our skin, many problems may not show up for a long period of time.

I think it would be interesting to know how much sunlight played a part in the development of cataracts and macular degeneration in the elderly.

I sure notice a lot more people wearing sunglasses than I ever have before. Some people won't even think about going outside without wearing sunglasses.

The EPF factor is something that can make a big difference in the long term health of our eyes - especially if we spend much time outside in the sun, or driving in our cars on sunny days.

By anon69206 — On Mar 06, 2010

no, infrared isn't the same as ultraviolet. ultraviolet is a higher wavelength than infrared.

By anon57048 — On Dec 19, 2009

No. Of course not. Ultraviolet is not the same as infrared.

By ledwedge — On Dec 17, 2007

Can I use Ultraviolet Ray eye protection to protect against Infrared Rays??

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