What should I do to protect my eye's health?

I spend about 5 hours before my computer with LCD screen. I have been using computers regularly for the past 7 years. I have not experienced any difficulty with my eyes so far. I play games and also deal with MS word documents a lot on my computer. I have no eye disease nor do I wear glasses. What should I do to maintain the health of my eye. Please suggest. This is just for the purpose of precaution against eye disorders.