I agree with the others re: possible bleph/MGD. That would explain the symptoms (tired, irritated, light sensitive eyes, worsening as the day goes along). I would suggest going back to the doctor with some really specific questions. I was just reading your other thread. Some doctors don't really examine the oil glands in detail and others, when they do, don't say anything about them so it really helps to ask specifically.
Ask them to press on your meibomian glands, and ask them to comment on what they're seeing. Is oil flowing freely? do they appear to be producing enough? is the oil thickened or poor consistency or discolored or are the glands blocked? Is there inflammation? Also, if you haven't already, post in Dr. Latkany's forum (with your photo).
The Dry Eye Zone