The 20-20-20 rule

To reduce eye strain and fatigue, follow the 20-20-20 rule: every 20 minutes, take a 20-second break and look at something 20 feet away.

Para reducir la fatiga visual, sigue la regla 20-20-20: cada 20 minutos, descansa 20 segundos y mira algo a 20 pies de distancia.

(https://www.aoa.org/healthy-eyes/eye-and-vision-conditions/computer-vision-syndrome)