As illustrated in Figure 1, the “visible light spectrum” is that small part of the electromagnetic wave spectrum seen as colors.
As shown in Figure 3, light first enters the optic (or nerve) fiber layer and the ganglion cell layer, under which most of the nourishing blood vessels of the retina are located. The light is received by photoreceptor cells called rods (responsible for peripheral and dim light vision) and cones (providing central, bright light, fine detail, and color vision). Until recently, the rod and cone photoreceptor cells in the retinas have been credited with total responsibility for light sensitivity. Another built-in protective process is that the natural lens takes on a yellowish tint with age, which helps to filter blue light.59 60 After cataract surgery, however, patients lose that benefit.
According to the CVRL Color & Vision database,63 light waves measuring approximately 470nm to 400nm in length are seen as the color blue. When light hits a photoreceptor, the cell bleaches and becomes useless until it has recovered through a metabolic process called the “visual cycle.” 30 31 Absorption of blue light, however, has been shown to cause a reversal of the process in rodent models. The CRI of a lamp is a number from 20 (effectively) to 100 that describes how well the lamp’s light emission affects the appearance and vibrancy of an object’s color.
A watt is a unit of power equal to work done at the rate of one joule (approximately 0.738 foot pounds) per second. Contrary to popular usage, a lamp is neither a fixture that holds a lightbulb or tube, nor is it “a light.” A lamp is the lightbulb or tube itself, which is contained in the lighting “fixture” (or “instrument”). Technically, there is no such thing as a true full spectrum lamp, but the term is used to define a light source with a CCT of 5000K or higher and a CRI of 90 or higher.
Fluorescent tubes containing the older halophosphate type phosphors emit light that is high in the blue spectrum.
Most fluorescent tubes now use a triphosphor mixture, based on europium and terbium ions, which more evenly distributes over the visible light spectrum. Commonly known as a lightbulb, an incandescent lamp contains a tungsten filament in a vacuum. Also called halogen, this lamp contains a filament made of tungsten, so it is a type of incandescent lamp.
The amount of harm from an LED, like any other lamp, is determined by the built-in protection of the product, in combination with reasonable precautions taken by the viewer. With growing evidence that both UV and blue light damage the retinas of people affected by, and at risk of, retinal disease, everything possible needs to be done to avoid aggravating the condition. Manufacturers promote FS lamps as more conducive to seeing than traditional lighting systems, based upon the belief that people see best outdoors on a bright cloudless day.
A growing body of research shows that the shorter electromagnetic waves of the light spectrum from blue (also called near-UV) through ultraviolet may be harmful. Lamps that imitate daylight and sunlight are said to help people see better, and some are even credited with helping to improve mood. At the time of the survey, one distributor had established an important precedent by publicly recognizing potential optical risks associated with high levels of blue light. Several lamp manufacturers provide products that offer intensity, contrast, and good color replication without the high color temperatures of full spectrum lamps.
To demonstrate the differences in lamp types, lighting products mentioned in this paper were acquired and compared.
A graphic of each lamp’s spectral distribution curve of radiant power overlaid on an image of the visible color spectrum. Observe each lighted section with the naked eye and then through an amber-colored gelatin sheet or 100% blue-blocker lenses.
Blue light emission becomes more apparent as correlated color temperature (CCT) increases for each type of lamp. Viewing with the naked eye the same picture lit with lamps of different color temperatures and keeping all other conditions equal, one notices distinct differences in hue.
When all are at full power, the fluorescent lamps 4-6 are less intense than the incandescent and LED lamps.
Incandescent and LED lamps are capable of several times the intensity of fluorescent lamps, and there is little danger of reaching hazardous blue light levels. Some incandescent and LED lamps have dimmers, which allow users to adjust the intensity to various comfort levels. The cost of the lamps themselves (the light bulbs, tubes, and LEDs) is similar for like-models.
Include a warning if the product presents a potential blue light hazard for people with retinal disease.
Provide accurate and complete specifications and descriptions so the consumer can make educated comparisons. In view of the expanding volume of research, plus the increasing number of people diagnosed with retinal disease each year, manufacturers are encouraged to voluntarily join the low vision community and eye care specialists in this education effort. For further scientific rationale and references regarding the potential blue light hazard, see Recommendation of protective eye wear for patients suffering from degenerative retinal diseases.(Ch. The following people are appreciated for their professional guidance and commentary in the writing of this paper. 16 Rozanowska et al Blue light-induced singlet oxygen generation by retinal lipofuscin in non-polar media.
18 Pawlak et al.Action spectra for the photoconsumption of oxygen by human ocular lipofuscin and lipofuscin extracts.
59 Mellerio J.  Light Effects on the Retina  Principles and Practice Of Ophthalmology Chapter 116  Eds. 70 Threshold limit values for chemical substances physical agents: biological exposure indices. This is where the nerves begin, picking up the impulses from the retina and transmitting them to the brain. The photoreceptors convert light into nerve impulses, which are then processed by the retina and sent through nerve fibers to the brain. Recent research, however, has shown that some of the ganglion cells may be performing as a third type of photoreceptor called “intrinsically photosensitive retinal ganglion cells” (ipRGC).1 2 These sparsely situated cells are most sensitive to blue light. As years go by, accumulation of lipofuscin (cellular debris) in the retinal pigment epithelium (RPE) may make the retina more sensitive to damage from chronic light exposure.6 7 8 9 10 11 12 13 14 15 Retinal light damage has been studied by exposing experimental animals and cell cultures to brilliant light exposures for minutes to hours. The blue bands of the visible light spectrum are adjacent to the invisible band of ultraviolet (UV) light.
It is determined by comparing the lamp with a reference source of the same Kelvin temperature (see below). This is a measurement at the light source (the lamp), not necessarily at the surface being lit. Phosphors in lamps are rare earth compounds of various types that glow during absorption of light radiation. The phosphors increase the wavelength of the invisible UV rays enough to convert them into visible light beginning at 400nm. With a blend of phosphors designed for a CCT of 5000K-6500K, these lamps come close to imitating the colors of daylight.

An electrical current causes the filament to glow (incandesce), while the absence of oxygen keeps it from burning up. It is different than an incandescent lightbulb, however, in that it contains a gas called halogen. When the diode is switched on, electrons are able to recombine with electron holes, releasing energy in the form of light. Consumers should arm themselves with good information to protect against the advice of marketers who may not be familiar with (or who ignore) the possible hazards.
That assumption is disputed by others who suggest that better vision under such conditions may be a result of increased light intensity and uniformity rather than color. For the best protection of health and pocketbooks, consumers should maintain vigilance about the facts and skepticism about anything that doesn’t pass the test of reason. Common sense should suggest otherwise, but common sense can sometimes be overridden even by people with the best of intentions. A person with early-stage macular degeneration can usually read well enough under standard lighting. They will, however, neither improve the health nor extend the life of retinal cells, a scientifically unsupported implication made by some manufacturers.
The company is Sunnex Biotechnologies, makers of the Lo-Light Therapy Lamp (a safe low-intensity lamp that screens out blue light). Listed below are examples of bright desk lamps and task lamps on the market with CCTs below 5000K.
The demonstration was designed with six lamps for an exhibit at the 2005 meeting of the Academy for Research in Vision and Ophthalmology (ARVO) and at other gatherings of researchers, eye care professionals, and patients. The blue light intensities of the lamps can be compared by viewing the posters through the amber gel provided or through 100% blue-blocker lenses. If the intensities of the fluorescent lamps were increased to match the obviously stronger output of the others, the amount of blue light would also increase, possibly compounding any hazard to the retina.
100% of more than 150 doctors surveyed at the ARVO convention concurred that the display lamps measuring below 5000K provided the best illumination, contrast, and color replication. Modern lighting technology can help people see better, but only through clear and honest marketing will the liability for proper decisions be theirs alone. Lutein and Zeaxanthin Dietary Supplements Raise Macular Pigment Density and Serum Concentrations of these Carotenoids in Humans.
A randomised controlled trial investigating the effect of nutritional supplementation on visual function in normal, and age-related macular disease affected eyes: design and methodology. Mechanisms of Blue Light-Induced Retinal Degeneration and the Potential Relevance for Age-Related Macular Degeneration and Inherited Retinal Diseases SLTBR Annual Meetings Abstracts 2003. The effects of fluorescent light on the ocular health of persons with pre-existing eye pathologies. The opinions expressed herein do not necessarily reflect their positions on the issues presented. The lipofuscin fluorophore A2E mediates blue light-induced damage to retinal pigmented epithelial cells. Blue light-induced apoptosis of A2E-containing RPE: involvement of caspase-3 and protection by Bcl-2. DNA is a target of the photodynamic effects elicited in A2E-laden RPE by blue-light illumination. Morphologic comparisons between rhodopsinmediated and short-wavelength classes of retinal light damage.
Guidelin es on limits of exposure to broad-band incoherent optical radiation (0.38 to 3 microM). Rhodopsin-mediated blue-light damage to the rat retina: effect of photoreversal of bleaching. Evidence for protection against age-related macular degeneration by carotenoids and antioxidant vitamins. Solar retinopathy: its significance for the aging eye and the younger pseudophakic patient. Resonance Raman measurement of macular carotenoids in normal subjects and in age-related macular de gener ation patients. Sunlight and the 5-year incidence of early age-related maculopathy: the Beaver Dam Eye Study. Light exposure and the risk of age-related macular degeneration: the Pathologies Oculaires Liees a l’Age (POLA) study. Rhodopsin-Mediated Blue-Light Dam age to the rat Retina: Effect of Photoreversal of Bleaching. Lipofuscin Accumulation in Cultured Retinal Pigment Epithelial Cells Causes Enhanced Sensitivity to Blue Light Irradiation. The nature of retinal radiation damage: dependence on waveleng th, po wer level and exposure time. Prevalence of senile cataract, diabetic retinopathy, senile macular degeneration, and open-angle glaucoma in the Framingham eye study.
Lipofuscin Accumulation in an Organotypic Perfusion Culture of Porcine Fundi Under Oxidative Stress and Blue Light Irradiation. Curiously, however, some lighting manufacturers say lamps duplicating sunshine are good for vision and eye health.
What are the differences between fluorescent, halogen, neodymium, LED, and regular incandescent lightbulbs? From the longest waves (lowest frequency) through the shortest waves (highest frequency), lighting specialists identify the electromagnetic wave regions as 1) radio waves, 2) microwaves and radar, 3) millimeter waves and telemetry, 4) infrared, 5) visible light, 6) ultraviolet, and 7) x-rays and gamma rays.
According to some of these studies,16 17 18 19 blue light waves may be especially toxic to those who are prone to macular problems due to genetics, nutrition, environment, health habits, and aging.
UV is located on the short wave, high frequency end of the visible light spectrum, just out of sight past the color violet.
This greatly increases the potential for oxidative damage, which leads to a buildup of lipofuscin in the retinal pigment epithelium (RPE) layer64 (see Fig.
Until research proves him to be either a friend or a foe, education will help consumers make decisions based upon the facts. Low CCT numbers define “warm” lighting, like the yellow and red hues of candlelight at 1500K. Only incandescent lamps, by the way, should rightfully be called lightbulbs, due to their bulbous (i.e. In common fluorescent tubes, UV rays are blocked mostly by the glass enclosure, protecting the eye to some extent from those harmful wavelengths. Blue light is an important component of that mixture, so the 470nm-400nm band is not only unfiltered, it is often enhanced in the manufacturing.
Neodymium bulbs, therefore, are often marketed as one of the types of modified-spectrum lamps, but they should not be confused with FS lamps.
Halogen recycles the burned particles of the tungsten, constantly rebuilding the filament and giving it a longer life.

The LED is usually less than 1 mm squared in area and contains components to shape its reflection and radiation pattern. At first hearing, for example, “Bright daylight is good for the eyes,” seems to make sense.
Reading in the dark makes them work too hard.” She meant well, but her suggestion should have been simply, “Turn on the light.
A person with advanced-stage macular degeneration, however, requires higher illumination and contrast.
Such lamps may be helpful for people with healthy eyes, but those who aren’t so lucky should think twice.
The only way to safely increase the intensities of fluorescent lamps to match that of incandescent and halogen lamps would be to significantly decrease the blue and UV wavelengths. The best contrast is achieved by the opposites of black and white, and that cannot be done with blue light.
Also, they emit yellowish light, whereas whiter light is preferred for better contrast and color replication by professional crafters, photographers, and artists. The lipofusion component N-retinyl-N-retinylidene ethanolamine detaches proapoptotic proteins from mitochondria and induces apoptosis in mammalian retinal pigment epithelial cells. These are the colors of a rainbow from top to bottom, which can be remembered by the fictitious name ROY G BIV. 3 4 5 The ipRGC have been shown to independently control dilation and contraction of the pupils, with a peak response at the blue light wavelength of 480nm. On the other hand, acute retinal phototoxicity experiments such as these can cause retinal injuries, but they cannot simulate a lifetime of normal light exposure. It does not express the range of a lamp’s light spectrum or the strength of it’s illumination (radiant power). Fluorescent lamps require an electrical component (a “ballast”) to create the arc that excites the gas. Part of the reason for that paucity may be because FS lamps are difficult to define and compare.
Major research shows that sunlight is a possible causative element in several retinal diseases, from retinopathy of prematurity to age-related macular degeneration.77 19. This section describes the display and discusses the most typical observations made by viewers. As the CCT increases from lamps 3 through 6, the blue portions appear increasingly brighter as the color green. Even those who do not fully agree with the research about the blue light hazard agree that low vision patients should be guided away from full spectrum lamps, if only because of their comparatively poor quality of light emission.
Age-related maculopathy and macular degeneration in elderly European populations: the EUREYE study, 2004. Recent Studies on Photodamage to the Eye with Special Reference to Clinical and Therapeutic Procedures. Maybe they will prompt you a great design of your kitchen, bedroom, bathroom, garden, basement or any other place. Before approaching these questions, it is important to have a basic understanding of light and its effects on the retina.
Some researchers have concluded through testing that the reaction of these ganglion cells is evidence of the importance of blue light to useable vision. Some researchers have noted strong similarities between photic injury and retinal abnormalities caused by years of overexposure to light.47 48 49 50 Others have found no similarities.
The effects of UV-C (100nm-290nm) are negligible, as the waves are so short they are filtered by the atmosphere before reaching the eyes.
Drusen are then formed from excessive amounts of lipofuscin, hindering the RPE in its ability to provide nutrients to the photoreceptors, which then wither and die. The type and blend of phosphors used in the coating determine the color of the emitted light. They are used in home, theater and automotive lighting, traffic signals, text and video displays, and communications technology, to name only a few of the growing number of applications. One should not, for example, gaze up close into a light box of blue (or even white) LEDs for longer than 100 seconds (the maximum recommendation from the International Commission on Non-Ionizing Radiation Protection). At the same time, people with retinal dystrophies need to diminish the progression of vision loss. They need bright lighting, but lamps that replicate sunshine might not only hasten sight loss, they can cause significant discomfort.
That kind of evidence should be enough to make those who are already visually-impaired wary of FS lamps. An opposing view is that such experiments are actually measuring the subject’s psychological reaction to the apparent increase in the field of view caused by the contribution of the ipRGC.
51 52 53 54 55 56 57 58 Whereas the shorter wavelengths of UV-A and UV-B are somewhat filtered by the lens and cornea, animal studies have shown that the light spectrum from UV through blue can be harmful. UV-A (320nm-400nm) and UV-B (290nm-320nm) are responsible for damaging material, skin, and eyes, with UV-B getting most of the blame. On the other hand, a small array of white LEDs (which contain some of the blue spectrum) in a lamp used for task lighting would probably cause little problem.
Until good science provides more definite answers, therefore, it might be wise to not bring the sun into the house and place it on the desktop.
Rhodopsin-Mediated Blue-Light Damage to the rat Retina: Effect of Photoreversal of Bleaching. AcrySof Natural Filter Decreases the Blue Light Induced Apoptosis in Human Retinal Pigment Epithelium. Remember that picking the correct lighting for your interior or exterior makes a defining impact on the design you create. They bear such imposing names as xanthophyll, melanin, superoxide dismutase, catalase, and glutathione peroxidase. Working out a lighting plan as you remodel your home will help you reach a desirable result. 35 36 37 38 39 Unfortunately, these defenses can weaken with disease, injury, neglect, and age.
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