It is concerning my friend who is 52 years old, OFF late his eyes giving him a lot of trouble. He is not able to concentrate or work even for 15 -20 minutes continuously as the eyes tighten and feel not able to focus on the computer. Not able to focus properly as see double or blurred image. If concentrate hard feel headache. He did not have glasses and used to take a lot of pride in his eyesight. Is it that he has developed a power or something. Is it common at this age. Can there be something more to it other than checking for power in his eyes for glasses.