I agree with the rest. I use artificial tears available OTC at chemists. I keep one in my bag at all times. You can also rinse your eyes every now and then during the day. Taking breaks from any monitor-related work, gazing into infinity (green trees, skies, or the ocean if you are lucky) are great eye-soothers. Placing your palm over your closed eyes for five minutes, for a few times during the day, can also help.