A comparison of accommodation and ocular discomfort change according to display size of smart devices.

Both devices showed significant decreases in NPA and NPC, and the larger changes were seen when using the small display smartphone. Even within 20minutes of using, subjects start to feel ocular discomfort, and it was more severe and faster after smartphones than tablets. Therefore, the smaller the display size, the greater the adverse impact on eyes, and thus, appropriate display size will need to be selected depending on the time and purpose of use.