You need to protect your eyes against the blue light emitted by smartphones. You can adjust your phone's screen settings. For example, turn on automatic brightness settings that allow your phone to adjust according to the environment. Text size can be increased to avoid straining your eyes when reading. You can also hold the phone at a sensible distance, such as 16-18 inches away from your eyes. If you must bring the phone closer, then zoom in on your screen. Another way is to turn on the night mode feature and enable your phone automatically adjust screen settings based on time of day. Consider acquiring an anti-reflective screen protector since it reduces glare from the sun or ambient lights. You can also use artificial tears to lubricate your eyes and blink a lot to refresh your eyes.