How My Eyes Felt After Two Weeks of Heavy Use of the Bigme 251 E-Ink Display

Jack Black Jack Black - 12月 27, 2025

Coding on Bigme 251 with a delicious lunch lovingly prepared by my wife

I've had the Bigme 251 for over two weeks now. During this time, I've had enough daily time to conduct a personal experiment on eye strain, testing whether using this screen for extended periods of work and study with the frontlight on causes any eye discomfort. My theory is, as long as the frontlight intensity is properly adjusted so that the light from the e-paper screen doesn't exceed the ambient light, using a color e-paper with frontlight on is just as eye-friendly as using a black-and-white e-paper without frontlight. (For a more detailed understanding of my theory, please refer to this article: "Does Turning On The Frontlight On Color E-Paper Defeat The Purpose Of Eye Protection"). Previously, I just hadn't been able to conduct this experiment for such an extended and continuous period.

Over these two weeks, apart from weekend family outings, I used this e-paper screen for about 10 hours each day (also testing Scott Young's "Ultralearning" method). The frontlight was set to level 4 for both cool and warm lights. What's the surface illuminance at this setting? Using the illuminance measurement methods from my previous articles "Tab Ultra C Frontlight Features and Recommended Usage" and "E-paper Frontlight Illuminance Comparison", I measured the white background illuminance of Bigme's frontlight at level 4 and found it to be 44 lux. This intensity is actually equivalent to the Tab Ultra C cool light set to level 17 (the middle position plus one more notch up). At the same time, I measured my MacBook screen's auto-adjusted white background brightness at 242 lux, and my ViewSonic monitor's white background brightness at 265 lux (already manually adjusted to the lowest brightness...). If you're still unclear about the relative illuminance strength of each device, you can refer to the chart I've attached, which shows comparative results tested with another illuminance software.

A reminder: different brands and different models from the same brand of e-paper devices have different brightness values at the same frontlight level settings. So please adjust to ensure the brightness doesn't exceed your ambient light level, rather than simply following my Tab Ultra C setting of around half brightness and setting your Kobo Colour to half as well - that's not correct!

This chart shows that the illuminance of backlit screen devices at the same level is significantly stronger than e-paper devices' frontlight

Every one to one and a half hours, I would get up and move around for 5-10 minutes, looking at distant objects to relax my ciliary muscles and avoid discomfort from excessive tension in these muscles. After two continuous weeks like this, how did my eyes feel?

The answer is absolutely no discomfort whatsoever! Not a single symptom of Computer Vision Syndrome! My eyes didn't feel dry at all, with no need for artificial tears. After using it for ten hours, I could even play Black Myth: Wukong on an LCD screen late at night for an hour without having to endure that burning, stinging sensation in my eyes - something that would have been completely impossible in the old days when working with backlit LCD computer screens.

In fact, I found using it this way more comfortable than using black-and-white e-paper.

Before my child was born, I could spend twelve hours on weekends for two consecutive days coding on the Boox 13.3-inch black-and-white Max Lumi (I was developing E Ink Mode for a while, see this article: "E Ink Mode Development Sharing"), but after a full day like that, my eyes would actually still feel slightly uncomfortable (though still much, much better than looking at an LCD backlit screen for that long). I suspect a few possible reasons: one possibility is font size - perhaps the Max Lumi's fonts are smaller than the Bigme's, making my eyes work harder. However, when I compared the Max Lumi in portrait mode with the Bigme screen's width, I found that the Max Lumi's screen length in portrait mode is actually similar to the Bigme's width (Max Lumi is slightly smaller), so I think the second possibility is more likely: white background reflection. When I was using the Max Lumi, sometimes under natural daylight, I actually found its white background too glaring. Some white paper uses optical brighteners to make the white background very white, which can also cause eye discomfort when viewed for extended periods. All of the above are my actual personal experimental experiences, which confirm both my own theory and Professor Chou Cho-Hui's theory from National Tsing Hua University. If you're interested, you can check out his two recent books: "Eye Protection: Start with Using the Right Light" and "Embracing Darkness", which contain very detailed theoretical explanations. Actually, how using TCL would feel can be deduced from the theories in these books, and over the past six months, the personal eye experiences shared by many community members using TCL match the results predicted by my theory. Additionally, some community members have mentioned that viewing on an iPad Pro in night warm light mode is much more comfortable for the eyes. I don't need to test this to know it's true, as Professor Chou's books explain these principles, but with the same warm light mode, e-paper's warm frontlight, when properly adjusted, will be much more comfortable for the eyes than iPad Pro's night mode. All of these have actually been tested in research papers. When I'm forced to accompany my child to sleep at night, I also use my TUCP with warm frontlight for reading. During Chinese New Year, I read through an entire book of "Piranesi" this way while feeding at midnight. (However, I still strongly advise against reading in complete darkness)

In summary, after more than two weeks of this self-experimentation, I'm very pleased that the experimental results align with the theory. There was actually a small incident during this period: one day in the first week, my eyes suddenly became extremely painful and unbearable. I was blinking frantically and desperately wanted to rub my eyes and massage around them. I thought at the time, "Ah~ maybe using the frontlight isn't what I thought it was~". Looking in the mirror afterward, both my eyes were bloodshot and completely swollen, and my nasal cavity started secreting massive amounts of mucus and became completely blocked. It turned out to be an acute reaction from food allergy! After going to the emergency room and getting two antihistamine shots, I was fine within a few hours, and afterward my eyes had no discomfort whatsoever. This shows that there are many causes of eye discomfort, and damage from light cannot be conflated with allergies, myopia, muscle fatigue, etc.

The purpose of writing this article is to share my own experience using e-paper and my eye sensations. Everyone's body is very different, and you and I may have different eye experiences with different usage durations. After all, this is not a meticulously designed scientific experiment, so everyone still needs to adjust according to their own feelings and work patterns. Some people may only use a computer screen for one or two hours a day, or don't read e-books at all, or have very fragmented and short electronic reading times - in those cases, there's no need to buy e-paper, a vivid LCD backlit screen or iPad would be fine. However, if you want to learn efficiently in the digital age, then I believe that e-paper will definitely be a powerful tool for high-intensity learning in this era, because it can simultaneously protect the health of your eyes, allowing you not just to sprint short distances, but to run a sustainable marathon.

Note

When using Boox's color e-paper tablets and readers, I don't need the frontlight 90% of the time. So why did I need to turn on the frontlight for the Bigme 251 experiment? Because although the Bigme 251 also uses Kaleido 3 (K3), its white background is actually darker than typical color readers using K3 (I suspect this is due to the screen component layers being too thick), so I couldn't use it without turning on the frontlight. However, the purpose of turning on the frontlight is only to compensate for the brightness absorbed by the screen, so even with the frontlight at level 4, it's still much darker than regular white paper. You can refer to the following two images.