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The victims of the current macular degeneration epidemic 

 

were the first generation who grew up under fluorescent lamps

 
 


Is fluorescent light safe for your children’s eyes?
by H. Peter Aleff
   

Installing energy-efficient compact fluorescent lamps, or CFLs, is being promoted as one of the most immediate actions you can take to help save our planet from global warming, and many countries and states around the world have passed or are considering laws to fade out the old energy-guzzling incandescent light bulbs.  However, most fluorescent lamps feature a strong blue-violet radiation spike in the most retina-damaging part of the visible spectrum, and prolonged exposure to this light while young could well be a major contributing factor in the now frequently accelerated onset of age-related macular degeneration, or AMD, among the first generation of people who spent their school years in fluorescent-lit class rooms.  

AMD results in severe blurring of the central vision. It used to be called “senile macular degeneration” because it affected mostly seniors in their seventies and eighties or even later[1], but it was renamed in about 1990[2] to reflect the gradually emerging new reality that by then it affected people at much younger ages than before.  Meanwhile, AMD has become the most common cause of irreversible functional blindness among older people, and the U.S, National Eye Institute included in its 2004 survey anyone from 40 years old on which is indeed much too young for the earlier label.  It estimated there that among this 40-plus group, seven million individuals in the U.S. had the early stages of AMD and were at risk of developing the more severe forms whereas another 1.75 million had already lost their vision to AMD.  The same survey also predicted that this number of severe cases will increase to three million by 2020[3] as many baby-boomers reach the critical age.

Several converging strands of circumstantial evidence implicate fluorescent light as a major contributor to this epidemic of AMD when you connect these dots:

·  The macula is the most light-sensitive part of the retina, at its center.

·  Epidemiological studies and other medical research have linked AMD, among several other risk factors, to the lifelong accumulation of retinal damage from light in mostly blue and shorter wavelengths which destroys photoreceptors and builds up their debris in the retinae of those affected[4].  This debris forms deposits that accumulate in the retinal pigment epithelium which is the layer just below the rod and cone cells of the photoreceptors.  The rate of this accumulation appears to be related to the retina's cumulative life-long exposure to light in retina-damaging short wavelengths.  For instance, The Eye Digest published by the University of Illinois’ Eye and Ear Infirmary mentions as the first in its list of possible risk factors “Exposure to sunlight especially blue light”[http://www.agingeye.net/maculardegen/maculardegeninformation.php]

·  Virtually all fluorescent lamps, including most of the recently introduced compact models, concentrate much of their energy in the so-called “mercury emission lines” which are intense spikes of energy emitted in the ultraviolet region by the excitation of the mercury atoms inside the lamp. The internal phosphor coatings of the lamps convert these invisible UV emission spikes into similar spikes at several specific longer wavelengths in the visible range.  The strongest one among these converted mercury lines typically accounts for about eight to ten per cent of all the energy emission from the entire lamp, and it shines at the blue-violet wavelength of 435.8 nanometer. This spike varies only slightly from one type of fluorescent tube to the next, whether they are called “daylight” or “deluxe” or are engineered to provide different color temperatures. 

Here is, for instance, a graph of the spectrum from a typical "Cool-white deluxe" fluorescent tube, in this case made by Sylvania:

Cool white deluxe fluorescent tube spectrum

You will also find a discussion of other fluorescent lamps  at retinopathyofprematurity.org/coolwhitedeluxe_spectrum.htm , including a link to the spectra of some compact fluorescent lamps as well as a Table of the damage-weighted retinal irradiance from each 5 to 10-nanometer wide band of the "Cool white deluxe" emission spectrum.
 

·  This salient emission spike at 435.8 nanometer is precisely in the most retina-damaging region of the visible spectrum, as determined by Laser safety researchers in experiments on many animals from mice to monkeys, and by examinations of human eye injuries from over-exposures in welding accidents or from staring at the sun. The Occupational Safety literature attributes the highest “blue-light-hazard” factors that cause maximum retinal damage to the wavelength region from 435 to 440 nanometer[5].

·  Adult eyes filter out most of this damaging light because our lenses gradually acquire a yellowish tint as they age, like varnish exposed to sunlight, and for the same reason which is the slow oxidation of free radicals.  This yellowing blocks much of the blue light and seems to be an adaptation to our having evolved under mostly blue skies that would have damaged our retinae without this protection.

·  Until their late teens or early twenties, children’s eyes are more transparent to blue and shorter wavelengths than those of adults. For instance, the age-yellowed lens of a 25-year-old lets through only 46 to 50% of the visible light, and next to nothing in the ultraviolet range. By contrast, the retinae of babies receive about 90% of the visible light above 400 nm plus 80 to 85% of the ultraviolet light down to about 320 or even 300 nm[6]. The hazard value of the violet and blue spectrum region is therefore much higher for children than the blue-light hazard function for adults. Both are shown in the American Conference of Governmental Industrial Hygienists’ Action Spectrum Table of Biological Exposure Indices[7], as copied from their 1997 edition at the bottom of the page retinopathyofprematurity.org/coolwhitedeluxe_spectrum.htm .

The risk factor for young eyes is closer to the values shown there for “aphake” eyes that do not have a lens, or only a fully transparent lens like that of children.

•  This lack of protection in children's eyes against so many short and energetic wavelengths may make you wonder why children playing in sunlight don't get their retinae destroyed as rapidly and severely as their early exposure to all that hazardous UV and blue-violet radiation might suggest. However, these children don't look directly at the sun, or at its most glaring reflections on water, snow, or white sand. These are much too bright to encourage staring at the source of that light without at least squinting to reduce the intensity of the light.  Also, our pupils adjust to that overall intensity and become smaller to let less of it in. The children's retinae receive therefore not much direct or strongly reflected UV irradiation, only weak reflections. As to the power of weakly reflected sunlight, you don't get a suntan if you sit on a lawn in the shade although your skin may get lots of reflected light from the adjacent sunny areas. Such weak reflections are also not likely to do as much damage to your or your children's retinae as direct exposures. 

On the other hand, fluorescent ceiling lamps are often in the visual field of those sitting in a room with them, and their overall intensity is usually not sufficient to make everyone automatically avert their eyes as the sun does.  And our pupils adjust their opening in proportion to the overall brightness but not to the local intensity of the narrow spike in the most retina-damaging region. That most hazardous component of the fluorescent lamp's radiation reaches therefore unprotected retinae directly in undiminished strength and causes slow photochemical damage in their most light-sensitive area, the macula.

•  Despite this relative absence of immediately noticeable harm from indirect sunlight, some eye doctors now recommend that children wear sunglasses outdoors. For instance, Dr. Greene at the Stanford University School of Medicine warns on his website: "Excessive exposure to sunlight during early childhood is harmful to the eyes. Sunlight contains harmful UV radiation. The risk for retinal damage from the sun's rays is greatest in children less than 10 years old, although the consequences usually do not become apparent until well after they are adults. Teaching your children to wear sunglasses may be more important than giving them a college fund."[8]

Similarly, Prevent Blindness America offers these tips to protect children from UV rays:  "Buy sunglasses that block the maximum amount (99 to 100 percent) of both types of UV-A and UV-B rays, fit closely to the face and have larger lenses for more coverage.  In addition to sunglasses, wear a hat to reduce overall exposure to UV rays. Don’t look directly at the sun.
Limit the amount of time spent outside during the peak sun hours (10 a.m. to 3 p.m.)"[9]

·  Fluorescent lamps were commercially introduced at the New York World Fair of 1938/39, and the people who now lose their sight clarity to AMD in their sixties and fifties or even sooner are the first generation who grew up under fluorescent lamps in their classrooms.

·  Exposing children not only in school but now even at home to direct fluorescent light from CFLs seems likely to worsen this early retinal damage and thereby to further accelerate the appearance of their future AMD, even beyond what the time spent in fluorescent-lit classrooms may have done to their parents.

The damage this “blue-light-hazard” irradiation inflicts on the retina is hard to observe immediately because the self-repair capacity of the photoreceptors gets used up very slowly. Like some equally elusive cancers or lung contamination diseases, the acute phase of this retinal disease appears after a long latency time of gradual damage build-up and typically manifests its harm only decades after the initial injuries.  This slow recognition of its initially hidden dangers may put fluorescent light in the same sobering category of first acclaimed but then shunned technologies as the now outlawed wildlife-poisoning DDT insecticide, ozone-depleting chlorofluorocarbon refrigerants and spraycan propellants, cancer-causing asbestos insulation, and brain-damaging lead additives for gasoline and paints.

The introduction of electric light provided a welcome contrast to this discouraging pattern of ignoring the downsides of new technologies because alert professionals quickly addressed one of its dangers.  A mere eight years after Edison strung up his first commercial incandescent light bulbs in New York, the oculists of London petitioned parliament in 1898 to pass laws against the use of unshaded lights, and consequently research was instituted on various types of shades and reflectors[10].

Unfortunately, the successors of those oculists were and are less vigilant.  When fluorescent tubes were commercially introduced at the New York World Fair of 1938 and 1939, none of the experts raised publicly any concerns about their unnaturally cold and harsh light.  None even acknowledged that the arrival of this new lighting type coincided precisely with the appearance, in 1940 in Boston, of a new type of blinding epidemic among premature babies, and that the same sequence repeated itself after World War 2 in many other industrial countries as fluorescent lamps became available there and were again followed closely by the local beginnings of the same now world-wide and still continuing epidemic[11].  Instead, the medical community welcomed the new lamps for the appearance of cleanliness their bright blueish light gave to hospital rooms, and for the reputed germicidal properties of the ultraviolet component in their radiation which many of the early fluorescent lamps did not yet filter out as well as most later models do. 

There were and will be no formal double-blind clinical trials to confirm the suggested connection between early exposure to fluorescent light and accelerated age-related macular degeneration. Obviously, researchers cannot expose people for decades under various controlled conditions to potentially harmful irradiations.  Without such validation by the “gold standard” of medical knowledge, the accelerated macular degeneration observed among the first generation who grew up under fluorescent lamps in their class rooms could be merely a coincidence and does not by itself prove any causation.  

However, if you connect the above dots then the weight and seamless fit of all this circumstantial evidence suggests to cautious parents the prudent motto "better safe than sorry".  Waiting for medical research to establish detailed dose-response curves of early retinal light damage for medical textbooks would be just a modern variation on the French playwright Molière’s quip that the purpose of medical science is not to cure patients but only to name their illness in Latin.  Even before vision researchers officially determine the severity of the expected long-term harm from specific exposures, common sense calls for protecting children's eyes from all hazardous radiation to rather prevent that harm in the first place. 

Continuing the use of incandescent light bulbs is at best a temporary stopgap measure because of their unsustainably high carbon footprint. But when you buy CFL bulbs, try the bug-lite versions which have a thick yellow coating and block most or all of the hazardous blue light. Their yellow light may take some getting used to, but it is safer and warmer than harsh blue light. 

It would also be useful to have a law requiring all manufacturers of CFLs to publish the spectrum for each of their lamp types, a parallel to food nutrition labels but for light bulbs, with their clearly stated output of hazardous blue-heavy radiation.  And to eliminate the fluorescent blue-light hazard altogether, ask Congress to provide incentives for a crash program to accelerate the development of affordable LED lamps with a balanced and eye-safe spectrum.

Postscript on May 6, 2013, about trying to halt or prevent macular degeneration with anti-oxidants and other nutritional supplements, see http://www.medpagetoday.com/Ophthalmology/GeneralOphthalmology/38884?
titled: "No Benefit for Aging Eyes with More Antioxidants" by Crystal Phend, Senior Staff Writer, MedPage Today, posted on May 5, 2013. It begins:

"Adding lutein, zeaxanthin, and fish oil to daily multivitamin supplements doesn't boost prevention of age-related macular degeneration (AMD) or cataracts in high-risk individuals, two analyses of the Age-Related Eye Disease Study 2 (AREDS2) showed.

None of the additions to the base antioxidant supplements had significant impacts on progression to advanced AMD, Emily Chew, MD, of the National Eye Institute in Bethesda, Md., and colleagues reported in the Journal of the American Medical Association."

 


[1]  David Miller: "Clinical Light Damage to the Eye", Springer Verlag, New York, 1987, pages 79-125.

[3] Prevalence of Age-Related Macular Degeneration in the United States, by The Eye Diseases Prevalence Research Group, in Citations and Abstracts from April 2004 Archives of Ophthalmology, as posted at http://www.nei.nih.gov/eyedata/pbd4.asp (accessed Jan. 01, 2010)

[4]  http://www.agingeye.net/maculardegen/maculardegeninformation.php, (accessed Jan 1, 2010), see page 5 of 10.  See also Waxler M and Hitchins VM, editors: "Optical Radiation and Visual Health", CRC Press, Boca Raton, Florida, 1986, see particularly chapter 6: "Optical Radiation and the Aged Eye" by Marshall J, Greenstein V, Kline D, Owsley C, and Werner JS. Quotes from Introduction and from page 118 middle to bottom: "The aging of the eye and the senile regression in visual perception cannot be studied in isolation from the lifelong cumulative effects of optical radiation. (...) The pigment epithelium is a closed system and with increasing age there is a net loss of cells from this layer with a resulting increase in size of those remaining. (...) Senile macular degeneration results from the metabolic disadvantage from the abnormal accumulation of debris between the pigment epithelium and the choroidal blood supply."  Also, "An increased exposure to 'blue light' has been reported to increase macular degeneration development", as stated at  http://www.agingeye.net/maculardegen/maculardegeninformation.php

[5] SLINEY DH, WOLBORSHT ML. Safety standards and measurement techniques for high intensity light sources. Vision Res 1980: 20: 1133-41 (see page 1137). See also the Threshold Limit Values (TLVs) for physical agents issued annually by the American Conference of Governmental Industrial Hygienists (http://www.acgih.org/home.htm).

[6] V.E.KINSEY in Archives of Ophthalmology 1948: 39: 508-13, see page 510 top; also

F.S. SAID and R.A. WEALE in Gerontologia 1959: 3: 213-31, see page 219 top; also

S. LERMAN “An Experimental and Clinical Evaluation of Lens Transparency and Aging”, Journal of Gerontology, 1983: 38:3, pages 293-301, see page 295 bottom left.

[7] American Conference of Governmental Industrial Hygienists:  “1997 Threshold Limit Values for Chemical Substances and Physical Agents Biological Exposure Indices”,  Cincinnati, 1997, see pages 118 and 119.

[8] see http://www.drgreene.com/qa/sunglasses-and-kids

[9] as cited at http://www.parenthood.com/articletopics/do_children_need_sunglasses.html :

[10] Encyclopedia Britannica, 1965, entry on Lighting, page 103 bottom right.

 

 

 
 

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