(Note: Emphasis in all quotes are ours)
"Results: While controlling for age and sex, we found that participants exposed to the summer sun for more than 5 hours a day during their teens, in their 30s, and at the baseline examination were at a higher risk of developing increased retinal pigment and early ARM by 10 years than those exposed less than 2 hours per day during the same periods."
"If cumulative sun exposure is related to the incidence of increased retinal pigment or early ARM, it is hypothetically the effect of exposure to visible rather than UV light. Previous studies have not found ARM to be associated with cumulative UV-A or UV-B exposure, but support associations between ARM and ocular exposure to visible blue light."
"Compared with age-matched controls, patients with macular degeneration had significantly higher exposure to blue or visible light in the preceding 20 years but were not different in respect to exposure to UV-A or UV-B. These data suggest that high levels of exposure to blue or visible light may cause ocular damage, especially later in life, and may be related to the development of age-related macular degeneration."
"Our data support the hypothesis that exposure to bright visible light may be associated with ARM (age-related maculopathy)".
"Several studies indicate that oxidative stress is one of the causes of age-related macular degeneration (AMD), the leading cause of irreversible vision loss among people age 60 and older in the United States. Retinal oxidative stress can be caused by light exposure, which has been implicated in the pathogenesis of AMD and other retinal degenerations. Photo-oxidative stress is caused by an imbalance between light-induced reactive oxygen species (ROS) and antioxidants. In the retina, absorption of light by photosensitizers results in electron transition to an unstable excited state [4], subsequently generating ROS. Photoactivation of lipofuscin yields singlet oxygen, superoxide anion, hydrogen peroxide, and lipid hydroperoxides. These photoinducible ROS have been shown to result in lipid peroxidation, enzyme inactivation, and retinal pigment epithelium (RPE) cell death."
"Age-related macular degeneration (AMD) is thought to be the result of a lifetime of oxidative insult that results in photoreceptor death within the macula. Increased risk of AMD may result from low levels of lutein and zeaxanthin (macular pigment) in the diet, serum or retina, and excessive exposure to blue light. Through its light-screening capacity and antioxidant activity, macular pigment may reduce photooxidation in the central retina."
"10-20% of individuals over the age of 65 suffer from age-related macular degeneration (AMD), the leading cause of severe visual impairment in humans living in developed countries. ... A precondition for AMD appears to be the accumulation of the age pigment lipofuscin in lysosomes of retinal pigment epithelial (RPE) cells. In AMD, these cells seem to die by apoptosis with subsequent death of photoreceptor cells, and light may accelerate the disease process."
"The present concepts of the pathogenesis of AMD include cumulative light damage by oxidative processes in the macular photoreceptors as environmental co-factor for the development of AMD."
"Oxidative stress plays a key role in the pathogenesis of Age-Related Macular Degeneration. ...Previous studies showed that xanthophylles (astaxanthin, lutein and zeaxanthin) cross the retina-blood barrier and bind to photoreceptor membranes, thus protecting them from light-induced damage."
"By absorbing blue-light, the macular pigment protects the underlying photoreceptor cell layer from light damage, possibly initiated by the formation of reactive oxygen species during a photosensitized reaction. There is ample epidemiological evidence that the amount of macular pigment is inversely associated with the incidence of age-related macular degeneration, an irreversible process that is the major cause of blindness in the elderly."
"It is now well established that photoretinopathy is a cumulative process, and chronic light damage may be one of the factors contributing to the development of age-related macular degeneration (AMRD)."
"Lipofuscin accumulation in the retinal pigment epithelium is associated with the onset of age-related macular degeneration. Lipofuscin is phototoxic and affects cellular function through the photochemical generation of reactive oxygen intermediates."
"The integrity of the retinal pigment epithelium, especially that of the macula is essential for the preservation of vision into old age. The chronic exposure to sunlight and peroxidized lipids from phagocytized photoreceptor outer segments imposes a high level of oxidative stress on the retinal tissues, which increases with age as antioxidant protection declines and therefore could accelerate apoptosis."
"The vulnerable person may, however, be a smoker with a high-fat diet and a history of high exposure to sunlight, all of which are known or suspected to heighten the risk of AMD....Protection from bright-light exposure might be a way to decrease production of A2-E.
the early stages of AMD can be imperceptible to the patient, or may be postponed by a life without the smoking, light exposure, or diet that may contribute to AMD"
"The RPE, already under high oxidative stress due to focused light, high oxygen concentration, and lipid peroxidation, may be even more sensitive to a shift in redox caused by smoking. This extra oxidative stress may contribute to the onset and progression of age-related macular degeneration (AMD) and be a factor in the link between smoking and increased risk of AMD."
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