Eye strain from heartbeat care and bright screen changes. Use contrasting display mode to highlight barriers and good headphones to separate rhythmic music.  Some of the Geometry Dash best players use their metronome app to lock in tempos, especially on levels when jumps fall out of step with the music. Consider lowering screen brightness to reduce eye strain, using high-contrast mode to highlight obstacles, and wearing good headphones to separate rhythm cues.  For difficult tempos, especially when the music and jumps are out of rhythm, some elite players use a metronome app.