Problem with my eyes?

Hi All

for the last few years, after a photo-session of at least 1 hour, sometimes less, my eyes really get strained and I cannot see 100% clearly for a few hours. But that I mean not so bad that I can drive or walk around but they just feel so tired - more a less like how you vision is almost immediately after waking up.

I wear glasses and am 47 years of age - may matter. Can anyone shed any light (no pun intended) on this and maybe advise on eye 'exercises(? .. is there such a thing) or anything I can do or one does where a lot of strain is put on eyes.

Thanks

TK