Blue light sits at the high energy end of the visible spectrum next to ultraviolet light. Over 50 years of research has consistently shown that blue light can cause both short and long-term damage to the retina. Blue light causes formation of free radicals that cause oxidative cell damage. Because this photochemical damage is cumulative even low intensity sources can lead to long-term to accumulation of lipofuscin and drusen, which are early signs of age-related macular degeneration (AMD). Concern over blue light from LED lighting and digital devices has led the French health agency (ANSES) and the International Organisation for Standardization (ISO) to publish reports that summarize the dangers of blue light. The ISO report (TR-20772) identifies the strong risk factors for AMD to be age, smoking, genetics, and low macular pigments, and specifies that blue light with wavelengths between 380-455 nm is the most dangerous to the retina.
Macular pigments strongly absorb blue light and act as antioxidants protecting the retina against photochemical damage. They are found densely concentrated in a thin layer immediately in front of the photoreceptors of the macular and are the reason you see a dark spot (macula lutea) when you observe the retina. They are only obtained from the food we eat and the amount/density that a person has depends on their physiology, diet, and lifestyle (e.g. smoking, sunlight exposure). The problem is that you can’t predict who has low macular pigments, they need to be measured. Several techniques for measuring macular pigments have been developed over the years but have failed to become part of regular eye tests due to length of test, need for pupil dilation, difficulty and cost. A new technique based on Haidinger’s brushes has recently been introduced and provides a means for wide-scale screening for those that are at greater risk of retinal damage from blue light and AMD.