Monday, January 29, 2018



(C) 2018 by Helios Ruehls, Inc.
It may have all started with a pigeons eye (Photo: Public Domain) 
As cutting edge optical physics researchers the Helios Ruehls crew does occasionally get involved in some areas of more general interest. One such area is called their "Yellow Lens Project". Most people would call the optical element examined "sun glasses", but their actual focus is on low light level vision enhancement, which is a far cry, by the way, from "night vision". Interest in the effects of yellow tinted lenses has been around a long time. At one point the Coast Guard noticed that certain birds appear to have yellow irises such as the pigeon depicted above. A few decades ago the U.S. Coast Guard's  aviation branch ran tests involving the performance of caged pigeons in helicopters at detecting "international orange" the official color of personal flotation devices ("life preservers", "life jackets"). The idea behind the tests was to compare the performance of the caged pigeons against the typical performance of the human crewmen serving as look outs . As far as the tests went the findings were rather positive in favor of the birds. 

 However, newer search and detection technologies ,including some non optical  technologies, became available and funding for the bird vision project dried up. As time went by certain innovations in aircraft cockpit windscreen design and instrumentation made the use of yellow tinted, polarized lenses dangerous in certain aircraft cockpits and with certain flight instruments. Basically many aircraft wind screens are polarized today as are the covers for certain flight deck instruments. Looking out through such windscreens or at such encased instruments while wearing polarized lenses creates a double effect that often results in being unable to see critical flight instruments or making the view out the polarized aircraft wind screen unreliable. The FAA regulations now virtually ban the use of polarized lenses and yellow tinted polarized lenses in particular from aircraft cockpits generally. Some have interpreted the regulation to bar yellow lenses regardless of polarization from the cockpit generally. Yet our research indicates that many aviators who fly older or simpler air craft might benefit from such eye wear under a variety of specific circumstances.  We have learned that many pilots of simple or older aircraft swear by the polarized yellow lens eye wear and some commercial pilots swear by un-polarized yellow lens eye wear even in the cockpits where the polarized version is definitely banned. 

 Thus based on our initial research we believe that a somewhat over generalized ban by the FAA has had a retarding effect on yellow lens research. We don't disagree with the FAA's ban on the use of polarized lens generally or yellow tinted polarized lenses in particular under a wide variety of circumstances, but think such lenses could be highly beneficial under certain circumstances. Those circumstances might include use in small planes without polarized windscreens in low light level situations such as nearing sunset or just after sunrise, or rainy conditions. Unpolarized light yellow tinted lenses might be of benefit to some pilots in similar ambient light conditions even in cockpits with polarized wind screens and instrument panels.  We believe that interpretations of the FAA ban as general and complete inhibit the needed research to create reliable guides on the use of such eye wear in aviation.

 Many shooters have found yellow lens eye wear to be vision enhanceive and the lens color is popular in shooter safety glasses. But too many manufacturers went overboard in their advertising and market yellow tinted eye wear as "night vision" eye wear or otherwise imply that the lenses enhance vision "at night". The Federal Trade Commission picked up on this and rightly labeled such advertising as "false". Unfortunately, we found the Federal Trade Commission was as unspecific and over generalized in their warnings as the manufacturers and distributors of the eye wear were in their "night" related claims of benefits. The net result is that the large body of evidence for the benefits of yellow tinted lenses in certain low light level applications has been buried under a combination of advertising and regulatory agency over statements. Below we endeavor to outline what we have been able to determine from applying simply good forensic investigative practice to a large body of authoritative literature and a small amount of original research conducted on our own. 

The truth,as indicated by our review of authoritative
 literature and interviews with actual users, is that most
 people could benefit from the use of yellow tinted 
 lenses  in lower ambient light levels on cloudy  rainy 
days, and first and last light. If anything can help "at 
night"  is the controversy that brought Helios
 Ruehls  into the study of existing authoritative 
literature , some physical testing of our own, and 
some interviews with users. Owning a  great pair of 
sunglasses is important for most people who spend 
any length of time outdoors routinely. UV rays are 
the number one cause of cataracts, macular, 
degeneration, and skin cancer around the eyes.
Ask any sailor,soldier, police officer, fireman, or 
outdoors-man, and they'll tell you how critical it is for 
them to have a durable pair of glare-resistant
sunglasses...and for them, not just any pair of
 sunglasses will do. Observe the marketing appeal from
 the makers of the Apache 400 "military" style 
sunglasses below.
"They were throwing flash bangs at us to disorient us, but thank god we had the new standard issue Apache 400 sunglasses. We were able to see exactly where we were going and where the enemy was. It's why I'm still here today."

Austin Grant, Special Ops

Thankfully, recent military advances in lens technology have taken sunglasses to a new level. Better UV protection and glare resistance in the form of polarized and other technologies have led to sunglasses that are many times better than your everyday sunglasses of yesteryear. But before you run out and buy a new pair, we think you need to hear about the research of Helios Ruehls, Inc. into tinted eye wear lens technology.  

 You also need to know about tinted lenses generally. The military type eye wear sell for between a reported $240 per pair to an occasional $79 or so on sale. Other yellow to amber tinted lenses make similar claims and are advertised on TV for prices like 19.95 . Based on their advertising, the "military like lenses" appear to be available in a shades of yellow, yellow /amber tint and a blue tint. We do not sell eye wear or draw any commission on any sales. We mentioned one vendor in this post simply to give you more information and an example of a non prescription/ non custom made product. WE ALSO DON'T RECOMMEND NOR DISPARAGE ANY OF THE "SUNGLASSES" OR TINTED LENSES THAT ARE PRESENTLY ON THE MARKET. What we are critical of is the apparent misalignment of certain marketing copy with the scientific facts relative to such lenses and the resulting apparent regulatory over kill relative to yellow tinted lenses. 

 Helios Ruehls, Inc. is still studying tinted lenses mostly from a marine navigation and aviation utility angle. We have distributed to a very limited group our initial preliminary report on usage in driving and to a lesser extent marine navigation. We are wrapping up our study of the usage of yellow tinted lenses in aviation and the related regulation. We believe the findings found there are far more reliable than the advertising copy of any tinted eye wear distributors.

 Two observations triggered the study of tinted lens performance by Helios Ruehls, Inc. First there was an observable growing popularity in the use of yellow tinted lenses, and a number of manufacturers / distributors were selling such as "night driving glasses". This triggered a complaint by the Federal Trade Commission of "misleading advertising". Second there were glowing reports on the effectiveness of yellow tinted lenses as enhancive of vision in low light levels. The initial research by Helios Ruehls revealed the following that in part explain the apparent contradictions:

1. "Night is a term describing part of the daily earth rotational cycle. It is not a description of any particular ambient light level."The ambient light levels that may be found during the time frame of "night" include brightly lighted ball parks and parking lots, streets with ordinary street lighting, conditions created by the various phases of the moon and available starlight away from urban light sources, to the serious "pitch darkness" of a densely cloudy, moonless night at sea. Helios Ruehls, Inc. found that the Federal Board of Trade's observations about advertising yellow tinted lenses as "night driving glasses" or anything similar indicating that such lenses had any sort of "night vision" quality amounts to a misleading claim is thoroughly correct. 

 However, Helios Ruehls research also confirmed that varying considerably with the individual user's personal vision physical characteristics, yellow tinted lenses could be a significant aid in visual perception under a wide variety of relatively low ambient light conditions."Night" being a time frame in which a wide variety of ambient light conditions occur, any total formal ban or public avoidance of the use of yellow or amber tinted lenses during the time frame of "night" could be counter productive under a variety of ambient light conditions. 

2. Helios Ruehls, Inc. found that the nearly uniform positive reports coming from certain US Air Force populations were  indicative of two facts: (1) Yellow tinted lenses more probably than not, do provide some visual perception benefit under some circumstances.(2) The reporting Air Force Population mentioned in the authoritative literature reviewed more probably than not represented an unusually uniform population characterized by a relatively narrow and young age band, and an unusually uniform proportion of the population with 20/20 uncorrected vision.

 Returning for a moment to the Apache 400 models. These may be ordered in both an apparent (based on advertising illustrations) yellow/amber tint and a blue tint. Helios Ruehls, in our own experiments, found that the  lighter the yellow tint , the wider variety of low ambient light levels the lens produced vision enhancive effects in. Conversely, the lighter the yellow tint the less benefit that could be derived in relatively bright sunlight. A yellow / amber tint or amber / yellow would fail as low light enhancive in lowering light conditions far sooner than a light yellow tint. However, the more amber the tint, the more utility in bright light. In fact amber and rose tints are often perceived as "color perception enhancive" by many reporting users. Moreover their red elements tend to enhance contrast and enhance depth perception. Amber to brown lenses are good in partly cloudy to sunny conditions. We have not tested the Apache 400 lenses and do not know if their apparent lighter amber tint extends their range of usefulness into lower light levels than conventional amber to brown lenses. 

 Blue tinted lenses, which the Apache 400 also comes in enhance contours, and colors generally and are considered vision enhancive in misty, foggy or snowy conditions. Our research however was focused on low light level visual enhancement. We could not recommend the Apache 400 eye wear specifically for that purpose. We could not tell from the advertising linked to, whether or not the Apache 400 models could be ordered with distance or astigmatism corrections.

 In fact in our search to build and test low light level vision enhancive eye wear we did not find a single mass market product that met all of our criteria, which was based on anticipated military needs as follows:

1. To extend the period of usefulness in low light levels the yellow tint should be as light as possible. 

2. The yellow tinted lenses should be polarized, or subjected to a similar process which both sharpened their glare reduction in low light and made them more useful when brighter conditions or "flash" were encountered such as on coming automotive head lights.

3.The yellow tinted lenses should be impact and shatter resistant to near safety glasses standards, yet lightweight. 

4. The yellow tinted polarized lenses should be able to be ground to take most common distance vision and astigmatic corrections, as outside of the military aviation community 20/20 uncorrected vision is not a strict requirement.  

 When we sought to have glasses made to these specifications in one market (New Orleans) we found that only a small minority of optical dispensing shops, both national chains and local or regional , could produce a pair meeting all of our specifications. The eye wear retailers who could produce our "test glasses" were affiliated with a single international lens manufacturer.  Our cost for the lenses alone were in excess of $300. 

 By contrast grey tinted lenses, polarized, impact resistant, and distant/ astigmatic corrected were commonly available at a wide variety of optical retailers. Grey tints, especially light grey are the best "all purpose" tints for a variety of light levels including cloudy and rainy days. But light yellow, corrected and polarized appears the best for the widest variety of low light conditions. Basically a consumer can walk into most optical retailers and order their correction as "grey tinted sunglasses" and come out with a very effective pair of "sun glasses" , depending on correction, thinness of the lens desired, impact resistance specified, frames etc for under $150 to over $300. Unless you have 20/20 uncorrected these will serve you better than the $79 to $240 "military" style "sunglasses". We think if you can benefit from the mass produced higher quality uncorrected lenses in the choice between yellow /amber and blue you will get more usage out of the blue. But the color enhancement, and contrast of those "military" style yellow amber red combination lenses when slipped over a pair of naturally seeing 20/20 human eyes is truly awesome.  

 We think the science is probably settled on the various tinted lenses but not very well understood by the marketing departments of much of the retail segment. Everything from light yellow to dark brown is generally marketed under the heading of "sun glasses", a few retailers are trying to market light yellow lenses as "night driving glasses"and running afoul of the Board of Trade. The FAA clearly discourages the use of yellow lens eye wear and this is especially appropriate in the case of polarized cockpit wind screens and instrument covers. There is no getting around that any tint once conditions are dark enough obstructs visual perception. The evidence is that the point of no gain varies widely among individuals. We do not agree with any general admonition that light yellow lenses, especially polarized and corrected would not be of visual perception assistance in "night driving" but hold that the effect varies with the level of ambient light and the vision of the individual user. The least controversial advertising claims come from the sale of yellow lenses to shooting sports enthusiasts . Configured as shooting safety glasses if the lenses make the grade for impact resistance standards no one seems to dispute the claims of vision enhancement made by shooters who favor the lenses. 

If you are a "Sunglasses" or "Night Driving Glasses" manufacturer, retailer, lens producer, or optical dispenser and would like to align your product descriptions, advertising, etc. with the upcoming copyrighted detailed research report by Helios Ruehls, or commission further investigation write to:

Helios Ruehls, Inc.
951 Marina Drive
Slidell, LA 70452  

RE: Yellow Lens Project, Initial Report

Please include your phone and E mail contact information.

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