Reading is reading—but the surface changes how the brain and eyes behave. A large systematic review and meta-analysis comparing paper to screens found a small disadvantage for reading performance on screens (overall effect size about g = −0.25). The gap looked bigger for expository text (fact-heavy, informational reading) and much smaller for narrative text (stories).

The same review found no reliable difference in reading time, but it did find that readers were less accurate at judging how well they understood when reading on screens. In everyday terms: people often feel like they understood a screen text, even when their test performance is slightly lower—especially for dense material.

Eye comfort is a separate issue from comprehension. Digital eye strain (also called computer vision syndrome) includes tired eyes, blurry vision, headaches, and dry eye, and a review estimates prevalence may be 50% or more among computer users. Two main causes are highlighted: (1) focusing and eye teamwork stress (your eyes constantly adjusting and converging at near distance), and (2) dry eye problems linked to reduced blinking or incomplete blinks during screen use. This helps explain why people can feel eye discomfort even when the text is large and readable.

Brightness matters most when it is excessive for the room or used late in the day. A clinical trial comparing evening reading on a light-emitting eReader versus a printed book found that the eReader condition led to longer time to fall asleep, reduced evening sleepiness, suppressed melatonin, a later circadian clock, and lower next-morning alertness. That is a sleep and timing effect—not necessarily “eye damage”—but it can matter a lot for health and daytime performance.

This is where eReaders differ from tablets. Many dedicated eReaders use e-ink displays, which are reflective (closer to paper) and usually much dimmer than tablets. That often feels gentler for long reading sessions, while tablets and phones are brighter, more contrasty, and more likely to tempt multitasking. A common myth is that “blue light from screens is destroying the retina.”

A narrative review on blue light notes that while blue light can cause photochemical reactions in eye tissues and damage is possible in lab conditions, there is currently no evidence that normal screen and household LED use is retinotoxic to the human retina.

Another myth: “blue-blocking glasses fix digital eye strain.” Systematic review evidence shows mixed results, and meta-analysis work has not found strong, high-certainty benefits for blue-blocking lenses in reducing visual fatigue.