[explorer1]

I read ebooks on the LCD monitor of my Windows PC. Monitor specs are: TN, 19", 89 PPI, CCFL backlight, brightness set to 0% when reading.

At 89 PPI, even with the latest sub-pixel rendering technology, text is not as clear as I would prefer.

I wanted 300 ppi, or at least 220 ppi, so that I can have text of acceptable clarity. So I recently bought an Android tablet, with 216 PPI display. I started to read an ebook on this tablet, with brightness below 20 %, and after 3 or 4 hours of reading on it, I've developed the following simptoms: red eyes (blood vessels on the surface of the eye expanded), itchy eyes, and fatigued eyes.

These simptoms were non-existent when I read on the pc monitor for 3 to 4 hours, and when I read on paper books for 4 hours. The display of this tablet differs from the pc display: it's IPS instead of TN, and it has led backlight instead of ccfl.

I don't know what, in this tablet, causes these eye problems. I don't know if PWM (Pulse Width Modulation) is the cause. Or if the combination of led + pwm causes it.

My questions are:
1. Why reading on this tablet causes red eyes, itcy eyes, and fatigued eyes ? All tables cause this problem, or not all of them ?
2. What can I do to make reading ebooks confortable for the eye ? I don't like night mode (white text on black backgroud), is seems harder to read, so are there any other solutions ?
3. Is reading on an e-ink display more confortable for the eye, than reading on tablets with lcd set to low bightness ?
4. I never read on e-ink before, but, for reading ebooks 4 to 8 hours per day, is it worth it to downgrade from 216 PPI of an lcd display to 166 PPI of an e-ink display ? I don't read outside, but I want to decide if it is a good idea to invest in an ebook reader.