Does blue light cause blindness? A recent article in the Guardian here has the headline “Scientists say they have found how blue light from smart phones, laptops and other digital devices damages vision and can speed up blindness.” This article and those in other media outlet are simply a rehash of the press release from the University of Toledo here rather than an actual reading of the paper here. In order to seemingly try and make their paper relevant the authors make a series of statements which cannot in my view be justified by the design or results of their studies as reported in their paper. The conclusion of the paper actually says “These findings suggest that retinal exerts light sensitivity to both photoreceptor and non-photoreceptor cells, and intercepts crucial signaling events, altering the cellular fate.” Interestingly the actual paper does not mention ‘blindness’ or ‘digital devices’. “prolonged exposure to blue light triggers poisonous molecules to be generated in the eye’s light-sensitive cells that can cause macular degeneration” The exposures mentioned in the paper were maximally 30 minutes and for the most part 5 or 10 minutes so how can they hypothesise about prolonged exposure. The paper does not mention ‘age related macular degeneration’. This study was not performed in humans or mammals or using human or mammalian retina cells. “We are being exposed to blue light continuously and the eye’s cornea and lens cannot block or reflect it.” Why given the importance of blue light to circadian entrainment should the cornea or lens block blue light? “The researchers found that introducing retinal molecules to other cell types in the body, such as cancer cells, heart cells and neurons, caused them to die off when exposed to blue light.” When would liver or heart cells ever be exposed to blue light? The scientists found that a molecule called alpha-tocopherol, a natural antioxidant found in the eye and body, stops the cells from dying but fails to offer any protection to the ageing population or those whose immune systems have been suppressed. α-Tocopherol is a type of vitamin E. Vitamin E exists in eight different forms, four tocopherols and four tocotrienols. α-tocopherol is preferentially absorbed and accumulated in humans. Very few people are deficient in vitamin E as a normal healthy balanced diet will provide the requisite amount of vitamin E. The authors give no explanation or evidence of the mechanism as to why alpha-tocopherol fails to protect in the aging population of those with a supressed immune system. “For those wanting to protect their eyes from blue light, Dr Karunarathne advises wearing sunglasses that can filter both UV and blue light outside and avoiding browsing on mobile phones or tablets in the dark.” It would seem slightly strange that the eye has evolved Intrinsically photosensitive retinal ganglion cells (ipRGCs) that are exquisitely sensitive to blue light, and are vital in entraining our circadian rhythms, if then that very blue light causes blindness. This would seem to be a failure of evolution especially since we evolved on a planet where the sky is blue. Who is going to put a blue-light filter on the sky? Or why after a million years of evolution do we need to suddenly wear sunglasses because the sky is blue. This story is lazy and sensationalist, all the journalist(s) have done is accept the press release taking the unsubstantiated claims of the study’s authors at face value without any attempt to subject them to any scientific or critical rigour or to actually read and understand the paper. I don’t know if blue light causes blindness in humans, but I do know that this paper certainly does not provide evidence for it .