Yes, of course eye strain can cause headache. As you have said that you are watching the computer for a long time the whole day. So it is easy for you to have eye strains. Also, you should know that there are long term effects of eye strains. For example, it can put stress on the eye muscles and the facial and scalp muscles, causing pain and headache. And what is worse, it can lead to making your vision become worse. And finally, you have to wear glasses. So to relieve your symptoms, you should pay more attention to your eyes. For example, you can drop some eye drops on your eyes. Besides, controlling the time you use eyes and the good position and lighting are also essential.