KORRUS / DOC-04 · MYTH BUSTING
Myth Busting
The standards haven't caught up with the science
Display health frameworks were designed around a narrow view of light safety. The science has moved on. The labels on the box haven't.
Myth 1
The Blue Light Hazard myth
Under IEC 62471 (the photobiological safety standard from which "blue light hazard" claims are nominally derived), every consumer display modeled falls into Risk Group 0, the regulatory classification for sources posing no photobiological hazard. The actual hazard classifications are reserved for arc welders, surgical illuminators, and the directly-viewed sun. Between consumer displays and the nearest hazard category sits a gap of four to seven orders of magnitude.
| Source | LB (W·m⁻²·sr⁻¹) | IEC 62471 | Margin to RG0 ceiling |
|---|---|---|---|
| Solar disc, midday, sea level | 1.1 × 10⁶ | RG2 | 11,000× above |
| Unfiltered GMAW welding arc, 200 A | ~10⁶ | RG2 | 10,000× above |
| RG0 ceiling · exempt threshold | 100 | · | 1× |
| Display at HDR peak (1,500 cd/m², transient) | 1.3 | RG0 | 80× below |
| Display at premium-laptop max (500 cd/m²) | 0.42 | RG0 | 240× below |
| Display at typical viewing (150 cd/m²) | 0.13 | RG0 | ~800× below |
Values computed from first principles for full-screen white-emitting displays at normal viewing geometries. Synthetic Gaussian-primary SPDs overstate LB 2–4× vs. spectroradiometer measurements of real LCDs (validated against O'Hagan, Khazova & Price, Eye 30:230–233, 2016). These are conservative upper bounds. Full methodology in the linked white paper.
What the ophthalmological societies and standards bodies say
American Academy of Ophthalmology
“Blue light from computers will not lead to eye disease… the small amount of blue light coming from computer screens has never been shown to cause any harm to our eyes.”
UK Association of Optometrists (2017)
“There is currently no evidence to suggest that visible blue light has any effect on the development of eye conditions such as age-related macular degeneration (AMD) or glaucoma.”
RANZCO (2020)
“The amount of radiation coming from a computer has never been demonstrated to cause any eye disease.”
Mainster et al., Am. J. Ophthalmology (2022)
“The blue light hazard is misused as a marketing stratagem to alarm people into using spectacles and IOLs that restrict blue light.”
CIE 2019 Position Statement
The CIE (the standards body that publishes the relevant action spectra) is explicit: “The blue light hazard is not an issue for white-light sources used in general lighting”, and the term “should not be used when referring to circadian rhythm disruption or sleep disturbance.”
Translation: the real display health concern is circadian, not photochemical. That is the metric (melanopic EDI per CIE S 026) and the regime where Korrus operates. See Circadian Rhythms.
On the skeptical literature
The skeptical literature on display blue light is part of the bibliography, not just rhetorical scaffolding. See Lawrenson et al. 2017 (BMJ Open Ophthalmology meta-analysis on blue-light-filtering spectacles), the AAO public guidance on digital devices, Phillips et al. 2019 on interindividual variability in evening light sensitivity, and the Mainster et al. 2022 AJO review. All linked in Bibliography.
Read the full analysis
Blue Light Hazard: What the Standard Actually Says
Ben Harrison, Korrus Chief Innovation Officer & Chief Scientist. 8 pages. Includes the underlying calculations and references.
Myth 2
UL CPF and the "circadian-friendly" software label
UL has begun marking displays as Circadian Performance certified based on the presence of features like CCT-shifting night modes. The problem: software night modes operate by remapping the panel's color output. They cannot independently control the melanopic content of the backlight. The actual melanopic reduction at the eye is modest and comes paired with amber tinting and color-accuracy loss.
Detailed analysis of UL CPF methodology and where it falls short to follow.
Why software approaches fall short
- • CCT shifting reduces short-wavelength content indiscriminately, degrading color accuracy as the side effect of the only mechanism it has.
- • Melanopic content is a property of the underlying backlight spectrum. Software at the panel layer cannot change it independently of color.
- • Certification of a software feature is not certification of a biological outcome.
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