It’s often said that one of the biggest innovations in the history of mankind was the candle. Bringing light into the darkness has continued to be an obsession.

Our thirst for light is illustrated by the rise of candle and soap maker Proctor & Gamble. It grew to be one of the biggest conglomerates in the world on the public’s demand for light.

True darkness is now hard to come by, just ask any astronomer. Light pollution has been blamed for everything from simple nuisance, to disrupting ecosystems and wasting energy.

The last of these issues was thought to have been mitigated by the development of light emitting diode (LED) lighting. First found as red indicators in electronics LEDs have since been developed to render light temperatures suitable for illumination. These temperatures bring the LED into the blue part of the spectrum.

The debate around blue light and its effect on the structures of the eye has raged for some time. The digital age had brought this debate front and centre in the optical world as lenses to filter out wavelengths around 460-480nm were developed. Wild claims about the benefits offered by these lenses has created an air of uncertainty.

But the debate is far from over, the latest research, linking blue light to breast and prostate cancer, will add fuel to that discussion.

As with any environmental factors definitive evidence is hard to come by. The wavelengths of certain LEDs may mimic those of sunlight but the intensity is miniscule in comparison. Disruption of circadian rhythms, duration versus intensity have all been discussed.

Optrafair offered a showcase for much of the latest evidence and thinking but optometrists are left to make their own judgements.

Light and the eye cannot be separated and the debate over blue light is far from over, your patients may well ask you for the answers.