Watchdog, episode 2, series 37 – BBC, 9 August 2016

You may have seen last BBC’s Watchdog show last night which featured an item on the sale of blue lens filters to block blue light. It showed optical staff in high street practices citing claims on the protective factors of certain lenses for blue light to customers.

The investigation was also covered in the Daily Mail, which you can read here.

While the programme focused on dispensing opticians, you may be interested in knowing what the College of Optometrists has to say about the sale of blue lens filters and whether you should invest in them.

Our Clinical Adviser, Dr Susan Blakeney explains: “There is no scientific evidence to support the use of blue lens filters to block blue light or that they can prevent long-term damage to the retina. I would recommend that patients take frequent breaks from looking at a screen by following the 20-20-20 rule: every 20 minutes, look 20ft away for 20 seconds to give the eye muscles a break. It’s always a good reminder to take a full blink when you are looking at a screen, as often people don’t blink properly in front of a screen and this can tire the eyes.”

You may have more questions about blue light and blue light filters, so Dr. Blakeney has answered a few below:

What is blue light?

Visible light ranges from blue, with the shortest wavelength, to red, with the longest wavelength. Blue light is produced naturally by the sun and artificially by electronic light sources.

Is it damaging to the eye?

There is no reliable evidence to say that using devices emitting blue light causes any permanent damage to eyes or eyesight. However, it may make users with pre-existing vision defects more aware of them. Blue light sources encountered indoors are unlikely to approach unsafe exposure limits, even for extended viewing times, and the eye possesses natural defences to mitigate blue light damage.

Are the eyes of children and older people any more susceptible to blue light?

When we are born, the crystalline lens inside our eye, which we use to focus from seeing far away to seeing close up, is clear.  As we get older, it naturally yellows and absorbs short wavelength (blue) light, protecting the retina. In addition to this, children’s pupils are larger than the pupils of older people, so that more light (of all wavelengths) reaches the retina of a younger person than of an older one. The combination of both of these factors means that more blue light will reach the retina of a child than that of an older person.

Does the crystalline lens transmit more blue spectrum light in the young?

Yes.  As the crystalline lens of a young person is clear, and the crystalline lens of an older person is naturally yellow, the lens of a young person transmits more blue light to the retina than the lens of an older person.