As to the eye strain, it caused by prolonged eye use. When using their eyes for computer work, people blinks less frequently. Tears coating the eye evaporate more rapidly during long non-blinking phases and this can cause dry eyes. Also, the air in many office environments is dry, which can increase how quickly your tears evaporate, placing you at greater risk for dry eye problem or eye strain.
If you are experiening computer eye strain especially the try eye, you could go to your doctor to ask for eye drops (artifical tears) to use during the working. It contains the ingredents which can lubricate your eyes and let you eye wet and feel comformtable.