Well, SOME UV rays damage human tissue. Not all, and not at the same rate. The shorter the rays get, the more damaging they are to tissue. But again, to claim that 401 nm is "safe" and 399 is "unsafe" is ludicris.Originally Posted by wss2020
Well, SOME UV rays damage human tissue. Not all, and not at the same rate. The shorter the rays get, the more damaging they are to tissue. But again, to claim that 401 nm is "safe" and 399 is "unsafe" is ludicris.
Partially correct; all UV does damage human tissue, as does some visible light. All UV is short enough in wavelength to hurt, and there is uncertainty where the ill effects end. The current thinking is about 500 or 550nm. Also, the dangerous wavelengths for skin don't superimpose exactly with the dangerous wavelengths for corneas, or lenses, or retinas. As you say, the ill effects don't just abruptly end, they taper off. Since the fallout from UV exposure is cumulative, any reduction is good, even if it doesn't constitute 100% reduction.
So a lens with a -2.00 cylinder power is ok wether it's 1 degree off or 3 degrees off?
At some point, there is a line between safe and unsafe. Doesn't matter how fine the line is, or how small a measurement it's done in, there is still a line. I'm not going to argue where the line is, I'm simply saying that there is a line.
As for UV protection in lenses, just give it to everyone. There's no harm in having UV protection in your lenses, regardless of their size, and regardless of what the cutoff range is for harmful/safe.
And remember, birth is the number one cause of death in the world, with a 100% fatality rate.
There are rules. Knowing those are easy. There are exceptions to the rules. Knowing those are easy. Knowing when to use them is slightly less easy. There are exceptions to the exceptions. Knowing those is a little more tricky, and know when to use those is even more so. Our industry is FULL of all of the above.
It is generally held that the cut-off for ultraviolet radiation is at 380 nm. Technically, "UV400" is a misnomer, since these wavelengths are actually visible to a typical observer if they are bright enough. Nevertheless, when discussing protection from radiation, both visible and ultraviolet, 400 nanometers is often considered an important cut-off.
UV radiation is obviously absorbed by the cornea and the crystalline lens. And we are all familiar with the association between certain forms of cortical and nuclear cataracts and chronic exposure to UV radiation below 380 nm. Only a small amount of UV radiation reaches the retina. But short-wavelength blue light radiation has also been implicated with certain ocular pathologies, in particular age-related macular degeneration. This is often referred to as the "blue light hazard."
Some studies have shown that chronic exposure to UV radiation and short-wavelength blue light may impact the function of photoreceptors and the retinal pigment epithelium, resulting in photochemical damage, cell death, and a more rapid build-up of waste products that accelerates further photo-oxidative damage, particularly in the sensitive macula. In time, this could lead to the deterioration of the retina, or macular degeneration.
The ability of radiation to disrupt ocular tissue is associated with the energy level of the radiation. And energy is inversely proportional to wavelength. So, like neighboring UV radiation, blue light has more energy than red light. This is exacerbated by the fact that the rhodopsin, which is a photopigment in the retina that has been implicated in the etiology of this process, has an action spectrum that peaks in the blue end of the visible spectrum.
So, protection from UVA and UVB radiation up to 380 nm may reduce the risk of developing cataracts. And protection from high-energy, short-wavelength blue light up to 400 nm may reduce the risk of developing age-related macular degeneration. Although, obviously, patients may still develop either of these pathologies over time. We're only talking about eliminating certain risk factors. But this isn't just a matter of "399 nm is bad and 401 nm is good."
Best regards,
Darryl
Darryl J. Meister, ABOM
Wow, I cannot believe some of the attitudes on this thread. Here's my thinking; who cares about cataracts we can fix those EASILY. What I'm more worried about is macular degeneration and per-orbital skin cancer. "UV400" where 400nm is used as the cut-off is used because the near-UV, which is still relatively high energy, has been implicated in macular degeneration. Is it 100% infallible proven fact? No.
Next big concern; skin cancer. You won't see much of this in the northern climates, but when I trained in Florida it was absolutely frightening the number of seniors with skin cancer - ears, nose, and eyelids VERY common.
Ideally, I want my patients in high index/poly/trivex/ or CR39 with UV for their regular glasses. Sunglasses should be large, high(er) wrap with backside AR. And yes, all emmetropes should have sun wear too - especially children, they will receive most of their lifetime UV exposure during childhood.
Originating Technology/NASA Contribution........................................
Ultraviolet-Blocking Lenses Protect, Enhance Vision
Health and Medicine
Originating Technology/NASA Contribution
Based on work done at NASA’s Jet Propulsion Laboratory, Eagle Eyes lenses filter out harmful radiation, reduce light scattering, and permit vision-enhancing wavelengths of light, protecting eyesight while also improving visibility.
In the 1980s, Jet Propulsion Laboratory (JPL) scientists James Stephens and Charles Miller were studying the harmful properties of light in space, as well as that of artificial radiation produced during laser and welding work. The intense light emitted during welding can harm unprotected eyes, leading to a condition called arc eye, in which ultraviolet light causes inflammation of the cornea and long-term retinal damage.
To combat this danger, the JPL scientists developed a welding curtain capable of absorbing, filtering, and scattering the dangerous light. The curtain employed a light-filtering/vision-enhancing system based on dyes and tiny particles of zinc oxide—unique methods they discovered by studying birds of prey. The birds require near-perfect vision for hunting and survival, often needing to spot prey from great distances. The birds’ eyes produce tiny droplets of oil that filter out harmful radiation and permit only certain visible wavelengths of light through, protecting the eye while enhancing eyesight. The researchers replicated this oil droplet process in creating the protective welding curtain.
The welding curtain was commercialized, and then the scientists focused attention on another area where blocking ultraviolet light would be beneficial to the eyes: sunglasses. In 2010, the groundbreaking eyewear technology was inducted into the Space Foundation’s Space Technology Hall of Fame, which honors a select few products each year that have stemmed from space research and improved our lives here on Earth.
Partnership
SunTiger Inc.—now Eagle Eyes Optics, of Calabasas, California—was formed to market a full line of sunglasses based on the licensed NASA technology that promises 100-percent elimination of harmful wavelengths and enhanced visual clarity. Today, Eagle Eyes sunglasses are worn by millions of people around the world who enjoy the protective and vision-enhancing benefits.
The Eagle Eyes lens (right) makes scenes more vivid because harmless wavelength colors such as red, orange, yellow, and green are enhanced, and damaging rays in the blue, violet, and ultraviolet (UV) wavelengths are blocked.
Product Outcome
Maximum eye protection from the Sun’s harmful ultraviolet rays is critical to our ability to see clearly. This is because when light enters the eye, a series of events happen which can help, hinder, or even destroy our eyesight. First, light passes through the cornea and ultimately reaches the retina which contains two types of cells—rods (which handle vision in low light) and cones (which handle color vision and detail). The retina contains 100 million rods and 7 million cones. The outer segment of a rod or a cone contains the photosensitive chemical, rhodopsin, also called “visual purple.” Rhodopsin is the chemical that allows night vision, and is extremely sensitive to light. When exposed to a full spectrum of light, rhodopsin immediately bleaches out, and takes about 30 minutes to fully regenerate, with most of the adaption occurring in the dark within 5 to 10 minutes. Rhodopsin is less sensitive to the longer red wavelengths of light and therefore depleted more slowly (which is why many people use red light to help preserve night vision). When our eyes are exposed to the harmful, ultraviolet light rays of the Sun (UVA, UVB, and blue-light rays), damage to our eyes and their complex vision-enhancing processes can occur and not even be noticed until years later, long after exposure.
The most common form of eye damage related to ultraviolet exposure, cataracts, causes the lens of the eye to cloud, losing transparency and leading to reduced vision and, if left untreated, blindness. In the United States alone, it is estimated that cataracts diminish the eyesight of millions of people at an expense of billions of dollars. Other forms of eye damage directly attributable to ultraviolet exposure include pterygium, an abnormal mass of tissue arising from the conjunctiva of the inner corner of the eye; skin cancer around the eyes; and macular degeneration, which damages the center of the eye and prevents people from seeing fine details.
Alan Mittleman, president and CEO of Eagle Eyes explains, “When we’re born, our eyes are clear like drops of water. Throughout life, we start to destroy those sensitive tissues, causing the yellowing of the eyes and the gradual worsening of eyesight. When the eye becomes more and more murky, cataracts form. Simple protection of the human eye, from childhood and throughout adulthood could protect the clarity of the eye and extend good vision for many years—even our entire lifetime.
“It has only been recently,” he adds, “that people started to realize the importance of this.” Sunglass manufacturers are recognizing the importance of eye care, and consumers are becoming more aware of eye health. One issue still plaguing the sunglass market, though, is that consumers assume that darker lenses are more protective, which is not always the case.
It may feel more comfortable to wear the dark lenses, but in addition to reducing the field of vision, it relaxes the eye, which allows more blue light to get directly to the retina. Blue light, in particular, has long-term implications, because it passes through the cornea and damages the inner retinal area.
The Eagle Eyes lens allows wearers to see more clearly because it protects from ultraviolet light, but more importantly, blocks this blue light, allowing the good visible light while blocking the harmful wavelengths.
Among their many donations throughout the years and goal of spreading good vision and eye protection to remote areas of the world, Eagle Eyes Optics had the opportunity recently to provide assistance to a group in sore need of eye protection: children in Galena, Alaska. The incidence of cataracts is 300 times greater in Alaska because of the Sun’s reflection off of the snow. Eagle Eyes donated 150 pairs of its sunglasses to a high school in Galena, and they were delivered by members of the Space Foundation and presented by former NASA astronaut Livingston Holder.
source> http://www.sti.nasa.gov/tto/Spinoff2010/hm_3.html
Maybe change idea..........................
For those who are calling any UV protection as being a marketing gimmick and call it garbage maybe above post might change their idea, but I doubt that too.
Where's the SCIENCE, the proof? All that is in that post is marketing baloney designed to convince the consumer. Darryl's post has far more scientific content than your marketing baloney post. Just because NASA was involved doesn't make it worth much more than a bunch of marketing words on a sales brochure.
And note that Darry's post contains a lot of "may". There is no hard fact science.
I don't discount the fact that UV causes damage, however, all sunglasses currently on the market provide UV protection. All lens materials currently available provide UV protection without additional needlessly expensive dyes or coatings. Trying to make the case for UV protection "because NASA helped develop it" is nothing more than a marketing ploy.
But I thought our eyes emitted "visual rays" in order to see. You mean we're also emitting UV??:bbg::bbg:
DragonlensmanWV N.A.O.L.
"There is nothing patriotic about hating your government or pretending you can hate your government but love your country."
The switch to modern plastics as the base lens material has made most use of UV coatings obsolete... although that hasn't stopped some from still trying to sell it as an expensive add-on.
"We recommend you apply the X-5000 bullet-proof coating to the windows in your new armored car."
"But aren't my bullet-proof windows already bullet-proof."
"Yes.... but why risk it. We recommend this add-on."
"Ummm...."
+1...
The consumer isn't told that modern base materials have UV inhibitors built into them. Why? Because it would eliminate the unnecessary additional addons by the unscrupulous optician.
Cheap shot, you must be proud of yourself.
1st* HTML5 Tracer Software
1st Mac Compatible Tracer Software
1st Linux Compatible Tracer Software
*Dave at OptiVision has a web based tracer integration package that's awesome.
Check out these charts-
http://www.opticampus.com/tools/tran...e.php?number=0
Also- If any newbies haven't checked out his courses you are missing something. Unfortunately the courses are not ABO approved. I wish they were.
Thanks Darryl!
Cheap shot, you must be proud of yourself............................................
Bravo Harry,........................People who belittle everything others say, do have a special reputation and you can find the description in many places on the net.
Light Damage in Cataract.....................................
Recent Developments in Vision Research:
Light Damage in Cataract
Possible risk factors for cataract include ultraviolet B radiation
(UV-B), diabetes, alcohol, smoking, diet, diarrhea, steroid
use, and certain medications such as corticosteroids."
Matters are complicated because age-related
cataract is not a single disease but, rather, three different
types of lens changes—cortical, nuclear, and posterior
subcapsular (PSC) opacities. Each has its own
pathogenic changes, age distribution, and almost certainly
different risk factors.
…………………….Other suspected sun-related ocular conditions include
acute photokeratitis, climatic droplet keratopathy,
pinguecula, pterygium, age-related macular degeneration
(possibly caused by exposure to blue light
or visible light, but not to UV-B), and possibly choroidal
melanoma.'
http://www.iovs.org/content/37/9/1720.full.pdf
"Unfortunately, people are generally unaware of when their eyes are at greatest risk for damage from UV exposure," said vision researcher Heather Chandler, PhD, from Ohio State University's College of Optometry. "This research involving UV-absorbing contact lenses can provide another option for protection against the detrimental changes caused by UV."
The study exposed rabbits daily to the equivalent of about 16 hours of exposure to sunlight in humans - enough to induce UV-associated corneal changes. The rabbits who wore UV-absorbing contact lenses (Senofilcon A) were not affected by the UV exposure.
Chandler said wearing sunglasses or hats may not provide enough protection from the sun, and adding adequate UV protection to contact lenses may be a practical solution to the problems caused by too much exposure. She also said that since this study focused exclusively on acute UV exposure, further long-term studies are needed to determine the efficiency of wearing the UV-absorbing contacts over a longer time period.
http://www.medicalnewstoday.com/articles/177284.php
We've all heard that ultraviolet light can damage our eyes and skin. But, as this ScienCentral News video reports, there's more and more evidence that visible light — the light we see by — may also be harmful.
Blue Light Special
Our eyes need light to work, but a body of research seems to suggest that too much of the wrong kind of light can lead to diseases like age-related macular degeneration. So as you head out to the beach with your sunglasses, keep in mind that they may not be protecting you from all of the damaging rays of the sun.
http://www.sciencentral.com/articles/view.php3?article_id=218392616
Well, Chris, since you are obviously in love with selling your own UV filter products, can you tell me exactly *WHY* you sell a product that fades/bleaches/wears off over time? If this is such an important issue to you, why sell a product with built-in obsolescence? The average pair of spectacle lenses is on the face for approximately 2 years, why sell a product that only lasts a couple of months, maybe 6 at most? Doesn't that put the patient at risk for UV exposure damage to the eye? Instead of shooting the messenger, wouldn't it be far better to work on improving the product so that it lasts 2 years?
If its such a cheap shot, then why did it hurt you so much that you had to comment on it?
Look at the charts that Uncle Fester posted. They come direct from the manufacturer. The materials already filter UV. Why add unnecssary additional filtering? The only reason I can see is to pick a little more money out of the unsuspecting publics' pocket.
have to remember the number of "opticians" out there who do not know about uv....also as with selling SCR on AR lenses
Obviously you are so taken away by belittling others that you are forgetting that you are talking total nonsense in a public forum with your signature and company on the post. What superb publicity.
There is only one material used for optical lenses that contains UV absorbers to their full value and that is Polycarbonate. That is also the link Uncle Fester posted above.
UV absorber can only be applied to lenses that have a porous surface as CR 39 or other materials containing a tint able hard coat.
UV absorber are made with Benzophenones in the optical industry, if it is by PSI, BPI, OMS, HILCO and or many others. These Benzophenons go into solution when they are heated to around the boiling point of the water the are contained in. The pores of the lens surface open under the heat, and the solution can penetrate into them. Depending on the solution and make it takes a certain time to complete this cycle.
The lens is then removed from the liquid and left to cool off. During this cooling off period the lens pores are closing up and the benzophenone contained in the pores is crystallizing.
As there are thousands of these pores across the surface, there are thousands of microscopic crystals contained on it. We now have the whole surface covered with crystallized lens pores that will be there permanently and are non removable. In the case of the Benzophenones I am using they will absorb UV 100% from 270nm to 400nm. Furthermore their effective protection will increase over time.
Actually I have still some glasses that were UV treated in 1983 in our lab and still measure 100% absorption on my CECIL reflectance, photo spectrometer. This is actually 28 years of continued and still working protection.
Mike, Obviously several statements you have made, are not worth the paper they are written on, because they deal with absolute fantasy.
I see a pattern...
1 Open mouth, insert foot.
2 Get called on anecdotal evidence and opinion presented as fact.
3 Attack relentlessly making up more unprovable claims to support prior unprovable claims.
4 Repeat until thread is closed by moderators.
5 Find another unsuspecting person to BADGER and nitpick.
6 Repeat cycle.
Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA
“As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein
There is hard science involved, but it is difficult to confirm these hypotheses experimentally, at least without frying someone's eyeballs. Mainly, these conclusions have been drawn from animal studies (we don't mind frying the rat eyeballs) and epidemiological studies. However, there is still the possibility that the effects observed in animals aren't strictly applicable to the human visual system and, with the epidemiological studies, it is difficult to prove causation simply from correlation.And note that Darry's post contains a lot of "may". There is no hard fact science
Hence, my carefully qualified use of "may," at least until the theory is truly proven and universally accepted. As many of you probably know by now, unless I know something as fact, I am careful not to represent it as such. A fairly comprehensive article regarding the effects of blue light radiation was written by Algvere, Marshall, and Seregard, "Age-related maculopathy and the impact of blue light hazard," Acta Ophthalmol Scan, 2006; Vol. 84, No. 1.
Best regards,
Darryl
Darryl J. Meister, ABOM
Not quite Wes. I respond only when attacked for having a different opinion that that of the "mainstream" who apparently would rather charge a patient for unneed product and toss a couple extra bucks in their pockets. That's the problem right there. It is about money, and commenting on something that is an unnecessary expense to the patient affects anyone who automatically puts an unnecessary product on a lens. It cuts the profit margin, and that causes people to get upset. I'm like a duck: it slides right off my back, and in fact, sort of proves my point in a roundabout way. If it wasn't about money, do you honestly think anyone would care?
Absolutely, Darryl, I meant no disrespect to you at all.
It is a quandry that everyone faces...but my point still stands: there is no hard evidence that UV between 380 and 400 nm causes enough eye damage to require additional filtration beyond what is already part and parcel of the lens material. There is supposition, hypothesis and plenty of urban legend. And what happens? We get products like UV dyes that filter UV for a period of time, slowly fading and/or wearing away, leaving, at some point in time, the patient "exposed" to that supposedly hazardous UV.
Where is the literature handed to the patient that explains that UV dyes degrade over time? If this is such a big deal, shouldn't this be part of the "Duty to Inform"?
These are the hard questions that no one wants to address, much less answer, and they'd much rather shoot the messenger than resolve it.
After using the Humphrey spexan, and BPI dual cal on a stack of CR39 jobs, I got readings of anywhere from 20-55% uv transmission. Granted, these aren't the best machines, but this clearly represents TO ME a need to uv treat CR39.
I don't believe that makes me an unscrupulous optician.
Wesley S. Scott, MBA, MIS, ABOM, NCLE-AC, LDO - SC & GA
“As our circle of knowledge expands, so does the circumference of darkness surrounding it.” -Albert Einstein
I certainly didn't find your post disrespectful, so no worries on my end.Absolutely, Darryl, I meant no disrespect to you at all. there is no hard evidence that UV between 380 and 400 nm causes enough eye damage to require additional filtration beyond what is already part and parcel of the lens material.
I agree that the jury is still out on the blue light hazard. At the same time, however, blue light in the 380 to 400 nm band certainly doesn't benefit the eye at all, so there is really no reason not to block it, if it has been implicated in some ocular health issue.
Best regards,
Darryl
Darryl J. Meister, ABOM
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