The most important thing to know with regards to the relationship between screens and the eyes is that the screens emit manmade blue light, however, our main source of blue light is sunlight and is natural.
Natural blue light is essential in our daily lives, limiting natural exposure to blue light will lead to negative medical and physiological effects, but overexposure can be serious and is linked to cancer, cataracts, macular degeneration, pterygium or pingueculae etc.
Leading ophthalmologist Dr CT Pillai explains what can happen if you have too much screen time and whether there's such a thing as a healthy amount.
Why is screen time considered bad for your eyes?
Our eyes are more susceptible to blue light given its wavelength scatters more than other visible light, which makes it more difficult to focus. For this reason, people can sometimes experience digital eye strain from screens. This can lead to sore, tired eyes, headaches and temporary blurred vision. As with any part of the body, you should not overexert yourself and take regular breaks and ensure that you look after your eyes.
Currently, more research is needed in this field, as it is debatable as to how much screen time is considered too much. Although there are concerns that manmade blue light could increase people’s risk to diseases related to the retina’s light-sensitive cells, for example, macular degeneration and Stargardt’s disease. Screen time has conclusively been linked to dryness of the eye, this is due to the reduced blink rate that occurs whilst staring at screens, which halves a person’s normal blink rate. The dryness can worsen and require treatment if the time looking at the screens is prolonged, regular or if a person is wearing contact lenses.
What’s the recommended screen time for children and adults?
With the rise in computer and TV use in children, the average usage time for screens is now 2 hours a day. Screen time is a prevalent issue given its potential to affect many people, young and old. However, there is no official guidance on the recommended screen time for children or adults. Opinions differ depending on the type of study that has been carried out. More studies have been carried out on whether excessive screen time has an impact on our psychological wellbeing rather than on our eyes because there has not been any definitive scientific evidence that screen time causes significant damage to the eyes.
The effects of screen time are different for every person, but it is important to take regular breaks to avoid eye strain when working for prolonged periods of time. The general consensus is that it is important that for every 20 minutes of screen time to shift your eyes away to an object 20 feet away for at least 20 seconds, this is known as the 20-20-20 rule.
Using screens close to bedtime may contribute to poorer sleep due to the suppression of melatonin (the hormone which makes us sleepy) which can affect the body’s natural circadian rhythm. However, there are so many other factors besides suppression of melatonin that are linked to disrupted sleep that it would not be accurate to claim that screen use by itself can be blamed for poor quality sleep.
Can screen time cause eye problems such as floaters?
Floaters are not associated with screen time. Floaters are caused by changes to the jelly inside the eyeball called the vitreous humour and are unrelated to screen time.
Is there any way to have some ‘healthy’ screen time?
It is important to have a balance in life. Too much screen time limits exposure to greenery, nature and sunlight and also prevents us from being active. Too much screen time can also cause the eyes to become tired and feel uncomfortable. It is best to listen to your body and take a break when the eyes start to feel tired and/or strained. The important thing is to be sensible and take into account the whole picture; the overall wellbeing of the body and mind.