- Author: Voya
- URL: Discord
Eyestrain comes primarily from two main culprits: The narrow lightwave band LED/OLED cells that have a pronounced and sharp intensity peak in the blue spectrum. This causes eye strain as it affects the blinking rate (lowering it) and dryness of the eyes. The blue light spectrum has also been medically shown that it has a negative effect on circadian rhythm, by suppressing melatonin for about twice as long as the green light spectrum does. Red spectrum has no effect on melatonin secretion. E-Ink screens eliminate that aspect entirely (any e-ink screen). Headaches/migraines can be caused by the blinking back light used in LCD/LED/OLED screens. This is usually due to the panels that use PWM (pulse width modulation) type of a backlight which operates on the principle of blinking at different rates. In combination with the screen refresh rate, if it blinks faster, the eyes will perceive the image as brighter. If it blinks slower, the eyes will perceive the image as darker. So basically brightness control is controlled by the blinking rate of the backlight. Needless to say, a large surface of light that blinks at you for hours on end is not a good thing 😉 And you’re kinda doomed if you do, doomed if you don’t in that situation, because if you lower the brightness to have lower blue light intensity being thrown at your eyes, you’ll have the blinking problem. If you up the brightness to minimize the blinking problem, you’ll have the blue light spectrum issue. And there is also the issue of the backlight being a direct source of light, meaning that it basically shines directly at your eyes, because LCD/LED screens are transmittent in their nature, so they produce an image by letting the light shine through the color cells. E-ink devices that have front light, operate on an entirely different principle, because the are a reflective type of a panel and do not rely on transmittance. So first of all, the front light brightness doesn’t use PWM, so it doesn’t blink. Second of all, normally you have a complete control over the cold (blue light spectrum) and warm (red light spectrum) at your disposal, so you are in control over what you want to use. And finally, front light doesn’t shine directly at your eyes, it shines at the screen and is then being reflected back to your eyes, and that makes a huge difference in the light spectrum that hits your eyes, when compared to a traditional back light. And finally nr 2, front light intensity is dramatically lower than the one of the back light, and that also plays an important role in this discussion.