Information Page for Therapists:
The Risk of Eye Damage from Bright and Blue Light Therapy
There is good reason to be concerned about retinal damage from the use of bright and blue light therapy lamps. Retinal experts have now determined that the development of Age-related Macular Degeneration (AMD) is directly related to the retinal stress that results from exposure of the eye to visible blue light. As Dr. Beatty, director of the Macular Pigment Pigment Research Group (MPRG) stated "It is photo-oxidative stress, or the cumulative exposure to free radicals from blue light over a lifetime that causes AMD".1a Recently the European Eye (EUREYE) Study "found that the combination of blue light exposure and low plasma concentrations of antioxidants was also associated with the early stages of AMD, which are common in the population, and that blue light exposure in middle age might be more damaging than at younger ages."1b
Hazardous blue light wavelengths do not contribute to the effectiveness of light therapy. While earlier studies suggested that blue light wavelengths would be highly effective for light therapy, more recent studies have found that monochromatic blue (479 nm) light is no more effective for light therapy than regular fluorescent white (polychromatic) light2. In 2010 a study from Harvard University confirmed that increasing the level of blue light wavelengths does not improve the ability of a light therapy lamp to influence human physiological functioning. 3 In comparision, a Sunnex Biotechnologies Lo-LIGHT lamp using the patented GreenLIGHT technology has been found to be more effective at inducing physiological responses than a blue-enhanced (465 nm) light therapy device that emits 10 times as much light.4
A number of studies over the past few years were unable to demonstrate that increasing the proportion of blue light wavelengths, i.e. visible light wavelengths shorter than 480 nm, emitted from a light therapy lamp would provide any benefit or increase in efficiency. It has also been known for several years that the inclusion of these hazardous blue light is not necessary for effective light therapy. In 2007 it was recommended that all light therapy devices screen out the potentially hazardous blue light wavelengths, and that light therapy devices emitting blue wavelengths of light should not be used. As one expert in light therapy stated, "It should be noted that broad-spectrum white light, traditionally used for bright light therapy, also contains blue light of potential concern particularly for very high intensity, long-duration exposure. Clearly, the safety of bright light therapy for people needs investigating. In the meantime it would be suggested that light in the 500 to 530 nm wavelength range (blue–green) should still be effective while avoiding the putative blue hazard".5a Recent studies strongly support this position.5b,5c
It is primarily the blue wavelengths of light (400-480 nm) emitted by light therapy lamps that are of concern.
Blue light contributes about 90% of the risk of photochemical retinal damage from fluorescent lamps and sunlight,
which is why the term "blue light hazard" is used to describe this risk. When blue light is absorbed by retinal
tissue it induces oxidative stress and the causes the formation of indigestible debris which accumulates in the
outer retina. The cummulative effect of chronic, sub-lethal oxidative retinal stress and the accumulation of
oxidative debris in the outer retina contributes to the development of AMD.
It can now be established that cummulative exposure to blue light over a lifetime contributes to the development of Age-related Macular Degeneration (AMD)6. Therefore, the use of blue or blue-enhanced light therapy lamps substantially increases the risk of earlier loss of vision, and has no offsetting benefit.
The risk of damage to the retina from blue light is increased in people with pre-existing retinal damage, those who use photosensitizing medications or supplements, and older people. The retina becomes increasingly susceptible to damage with age, because the accumulating oxidative debris is phototoxic to blue light, and because defense mechanisms that protect the retina from oxidative damage progressively deteriorate after age 40.
The largest American epidemiological study indicates that a moderate daily increase in exposure to blue light of young adults, in their teens and thirties, advances the onset of macular degeneration later in life by 10 years. This would double the likelihood of becoming blind in one’s lifetime7a, 7b. Several specialists involved in macular degeneration research now recommend sunglasses that block blue visible light be used by people of all ages to limit the amount of blue light reaching the retina over a lifetime.
AMD is a severe problem that is approaching epidemic proportions. 25% of people in the developed world will have vision problems caused by AMD by age 75, (10% of people aged 65-74 and 25% over 75 have severe vision loss) 8a. For people with a family history of macular degeneration, the prevalence of severe vision loss increases to 54% at age 75, and 64% at age 858b. As retinal oxidative stress is a causative factor for the development of AMD, increasing levels of exposure to blue light wavelengths from light therapy lamps can only increase the likelihood of developing AMD.
The consequences of macular degeneration for people who find light therapy beneficial are severe. Herbert Kern was the first recipient of light therapy for the treatment of a mood disorder(SAD). In an article in recognition of the 25th anniversary of the use of light therapy to treat mood disorders in the journal Science (Sept, 2007), after decribing how [bright] light therapy became less and less effective for him over the years as his eyesight faded from AMD, he stated, "Now I can hardly see, and all hell has broken loose...I have had periods of depression lasting over a year".9 See ENDNOTE below
There are a number of factors inherent in the manner of use of light therapy that increase the risk of retinal damage and the resulting loss of vision by users of bright or blue light therapy. For a more complete, annotated discussion of this risk please see Risk Factors of Bright and Blue Therapy
A Short Synopsis of the Pathogenesis of Macular Degeneration Induced by Blue Visible Light
The known pathogenesis of Age-Related Macular Degeneration (AMD) involves chronic elevated levels of oxidative stress, chronic inflamation, and the accumulation of oxidative debris in the outer retina. The outer retina includes the photoreceptor cells, an adjacent monolayer of retinal pigment epithelium (RPE) cells, and Bruch's membrane, a complex that acts as a retinal-blood barrier through which the nutrients and oxygen needed to sustain photoreceptor cells and RPE cells must pass. AMD occurs within a small area of the retina called the macula and is associated with malfunctioning of RPE cells adjacent to the macula and with the accumulation of oxidative debris within these cells (lipofuscin), and with the accumulation of oxidative debris on the basal side of the RPE, where this material can become cross-linked to the Bruch's membrane complex, and form drusen. The formation of drusen is considered to be the initiation of the process of AMD. The macula of the retina contains the fovea, which is the retinal area primarily responsible for vison. Retinal oxidative debris substantially consisting of indigestible material generated from oxidative damage to lipids and lipoproteins, is associated with the absorption of light by photoreceptor cells, and the absorption of blue light wavelengths and mitochondrial malfunctioning in RPE cells. Lipofuscin accumulates in RPE cells over a lifetime, and generates large amounts of radical oxygen species when it absorbs blue visible light. These radical oxygen species are capable of directly inducing cell death, of causing chronic inflammatory responses in the outer retina, and of generating additional oxidative material.
An accumulation of material between the RPE cells, which nourish and remove waste materials from photoreceptor cells, and the Bruch's membrane complex limits the access of RPE cells to the blood supply for absorbing nutrients and disposing of metabolic waste. Impairment of all of these processes are associated with the slow deterioration of vision called "dry macular degeneration".
The generation of the large amounts of radical oxygen species and the resulting oxidative stress can induce damage to the Bruch's membrane complex separating the retina from the blood supply, and promote its permeation by small weak capillaries. When these small capillaries invade the macular region of the retina they are susceptible to leakage. This leakage into the retinal space results in a rapid deterioration of vision that is known as the “wet” form of macular degeneration. For a more complete annotated discussion of the role of visible blue light in the pathogenesis of AMD. Please see A technical discussion on the contribution of exposure to blue light (400-480nm) to the pathogenesis of AMD.
Sunnex Biotechnologies' Lo-LIGHT technology is a safe, low intensity alternative to bright light therapy. It is the only light therapy device that filters out the dangerous high-energy blue light rays. While some "blue light" therapy devices emit wavelength in the 460-465 nm range, which is 70-80 % of the maximum blue hazard, the blue-green light ( peak 500 nm) used in the Lo-LIGHT is less than one-tenth as hazardous to the eye as blue light with a wavelength of 440, where the blue hazard peaks according to the International Commission on Non-Ionizing Radiation Protection.
1a. The Irish Medical News. July 2007.
1b. Sunlight Exposure, Antioxidants, and Age-Related Macular Degeneration. Arch Ophthalmol. 2008; 126:1396-1403.
2. Light-Induced Melatonin Suppression in Humans With Polychromatic and Monochromatic Light. Chronobiology International, Nov 2007; 24(6): 1125–1137 Revell VL and Skene DJ.
3. Spectral Responses of the Human Circadian System Depend on the Irradiance and Duration of Exposure to Light. Science Translational Medicine 2010 May 12; 2, 31ra33. J.J. Gooley, S. M. W. Rajaratnam, G. C. Brainard, R. E. Kronauer, C. A. Czeisler, S. W. Lockley
Read more on confirmation that increasing the proportion of blue light provides no benefit for light therapy.
4. Circadian Phase Delay Induced by Phototherapeutic Devices. Aviation, Space, and Environmental Medicine. July 2007; 78(7):645-52 Paul MA, MillerJC,. Gray G, Buick F, Blazeski S, Arendt J.
5a. Clinical Management of Delayed Sleep Phase Disorder. Behavioral Sleep Medicine 2007, Vol. 5, No. 1, Pages 57-76. Leon C. Lack
5b. Impact of blue vs red light on retinal response of patients with seasonal affective disorder and healthy controls. Progress in Neuropsychopharmacological and Biological Psychiatry 2011; 35(1):227-31. Gagne et al.
5c. Retinal Photodamage by Endogenous and Xenobiotic Agents. Photochemistry and Photobiology. (In Press May 14, 2012). Wielgus AR,and Roberts JE.
6. Read more on demonstrating cummulative blue light exposure contributes substantially to the development of AMD
7a. Sunlight and the 10-Year Incidence of Age-Related Maculopathy: The Beaver Dam Eye Study, Correction. Arch Ophthalmol. 2005 Mar;123(3):362} Tomany SC, Cruickshanks KJ, Klein R, Klein BE, Knudtson MD
7b. Sunlight and the 10-Year Incidence of Age-Related Maculopathy: The Beaver Dam Eye Study. Arch Ophthalmol. 2004 May; 122(5): 750-7} Tomany SC, Cruickshanks KJ, Klein R, Klein BE, Knudtson MD
8a. Opening New Fronts in the Battle Against AMD. Review of Ophthalmology May 2007, 14(5). TA. Ciulla
8b. Age-related Macular Degeneration in Very Old Individuals with Family History Asbjorg et al. American Journal of Ophthalmology May 2007. 143(5):889-890
9. Psychiatric research. Is internal timing key to mental health? Science. 2007 Sep 14;317(5844):1488-90. Bhattacharjee Y.
10. Do blue light filters confer protection against age-related macular degeneration? Prog Retin Eye Res. 2004 Sep;23(5):523-31. Margrain TH, Boulton M, Marshall J, Sliney DH.
11. Light-Induced Damage to the Retina: Role of Rhodopsin Chromophore Revisited. Photochem Photobiol. 2005 Nov-Dec;81(6):1305-30. Review. Rozanowska M. Sarna T
Some manufacturers of light therapy units that emit high proportions of blue light wavelengths claim that an authoritative source has determined their products are safe. An examination of these claims show that the rationale for the safety of these products is based on the intensity of blue light needed to induce a retinal lesion in an animal retina, 50% of the time. This manner of analysis for acute retinal damage, whether flawed or not, is not logically applicable to a determination of the hazard to vision from AMD, the pathogenesis of which appears to be related to cumulative sub-threshold retinal stress over a lifetime.
The same authoritative source cited by these light therapy device manufacturers to support the claim their devices are safe is an author of a paper that states "we believe that there is support for the long-held belief that light has a role in the pathogenesis of ARMD. That is, the recent findings that antioxidant therapy has a protective effect confirms that oxidative stress has a role in the pathogenesis of AMD and laboratory studies have demonstrated that light, and in particular blue light, is a source of oxidative stress via its interaction with retinal chromophores. Therefore a reduction in blue light exposure might reasonably be expected to reduce progression in ARMD"10 This is consistent with other investigators who have explained that "avoiding exposures to bright short-wavelength [blue] light is the simplest preventative measure against light damage".11
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