Rhodopsin mediated photoreversal: A response to Blue-Light Hazard and LEDs: Fact or Fiction?

A response to the misinforming article published by Architectural Lighting Technology by Alice Liao

Rhodopsin mediated photoreversal - By Mr B Dove.

Rhodopsin mediated photoreversal is the actual process by which blue light (approx. 460nm and shorter wavelengths) damages the retinal pigment epithelial tissue, causing damage and eventually deterioration of the retina. The energy from the photons in blue light causes the phototransduction cascade to be instantly reversed, and for the cell to constantly fire until it kills itself. This only occurs with a SPD that has large amounts of blue wavelength light, and an absence of other wavelengths (which normally prevents photoreversal).

The critical thing to understand about this damaging process is that its dependent on the WAVELENGTH, NOT THE INTENSITY. Let me repeat that. Its NOT based on intensity.

Even very low intensity light, with a spectral power distribution that includes disproportionately more blue light than other wavelengths, causes rhodopsin mediated photoreversal and damage. That's why these studies and articles that claim that LEDs aren't as intense as sunlight and are therefore safe, are absolutely ridiculous. 

The human retina adapts to bright light and becomes exponentially less sensitive. That's another reason why using high intensity light source studies is pointless. Yes, extremely bright light from the Sun, arc lights or welders will damage your eyes, but NOT through the same process that low intensity blue light does. That is NOT why blue LEDs, fluorescents, or really any source of very blue light is bad: rhodopsin mediated photoreversal is.

And before you say "but the sky is blue", keep in mind that overhead daylight is 5500K CCT and the sky is blue, but overall the atmosphere filters sunlight to a very yellow 5500K CCT. More importantly, the SPD of sunlight is mostly infrared through green on Earth and NOT blue. In space it's much bluer and more damaging, but astronauts wear the appropriate protection.

TL:DR Low intensity blue light is MORE eye damaging than bright sunlight.

Reference

Architectural Lighting 2016 http://www.archlighting.com/technology/blue-light-hazard-and-leds-fact-or-fiction_o

Grimm, C 2001 www.ncbi.nlm.nih.gov/pubmed/11157889

Yau, K 2009 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2885920/

Zhou J 2011 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3100371/