How much damage blue light actually does to your eyes

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There’s no escaping blue light in the modern world. From digital devices, computers and phone screens, to fluorescent bulbs and LED lights, blue light is everywhere we turn. And the biggest source of it? Natural sunlight. With the number of blue-light-blocking products being touted in the market today, it’s easy to assume that blue light is physically harmful to our eyes. But how much damage does it actually do? “The truth is, nobody knows with certainty,” says ophthalmologist Dr Claudine Pang, founder of Asia Retina Eye Surgery Centre. “There have been no human studies to document retinal damage by blue light. For this reason, we tend to err on the side of caution and try to limit excessive blue light exposure to our eyes.”

Some amount of blue light exposure is good for us

“It is unscientific to equate all blue light as harmful. We actually need some amount of blue light to regulate normal circadian rhythms, boost alertness and memory, and prevent development of myopia,” says Dr Pang. “Blue light deprivation has even been shown to be associated with depression-like changes in the brain.” What most of us should be worried about is excessive, prolonged exposure – but to be fair, almost everything is harmful in excess. And because our retina can’t block blue light at all, that’s where specialised lenses and screens come in. According to Dr Pang, blue-light-blocking lenses are able to block 20-70 per cent of blue light, depending on their quality. Blue light occupies the 400-490 nm wavelength, and the yellow tint of blue-light-blocking lenses filters out wavelengths less than 450 nm, which may increase eye comfort when viewing digital devices for extended periods of time.

The negative consequences are more behavioural than physical

The real concern with blue light is actually behavioural. “The most conclusive consequence of prolonged exposure of blue light is that it affects the normal secretion of melatonin at night and disrupts our normal sleep cycle. Therefore, we should reduce the use of electronic devices especially at night for better sleep,” says Dr Pang. This disruption of our natural circadian rhythms affects the quality of our sleep, which has a host of other consequences like increased risk of obesity, heart disease and diabetes. And the tiredness we feel after looking at our screens for too long has more to do with digital eye strain than any physical damage caused by blue light exposure. Spending too much time looking at a screen reduces blinking, which results in dry eyes, discomfort, and blurry vision.

These issues are exacerbated by poor lighting, such as when you’re scrolling through social media in bed.

The important thing to remember when it comes to eye health to take regular breaks between screen time. There is a simple 20-20-20 rule you can follow: look away from your screen at least once every 20 minutes, looking 20 metres into the distance for at least 20 seconds. In Dr Pang’s parting words, “As with most things in life, regulating blue light exposure is about moderation.”

This article was first published in Her World Online.