It is not. Working at a computer will not damage your eyes. However, long days at the computer can produce aesthenopia or eye strain.
Rest. Sitting many hours in front of the computer can lead to eye strain, fatigue, watery or burning eyes, irritation and redness from dry eyes (blink less). Best to take occasional breaks, since staring at that fixed screen distance can lead to constant accommodation and even more myopia progression in younger individuals.