Checking the "eyes get worse during the day" hypothesis

Many PRK blogs mention that their vision gets worse during the day and I have noticed mine slip a bit, so I wanted to see how much worse mine gets during the day. I did these tests in the same order, with the same # of artificial tears, same lighting, same computer (I always use the same lighting and same computer).

Left eye:

12pt: 69% (this morning: 81%)

18pt: 92% (this morning: 92%)

27pt: 96% (this morning: 97%)

all others 100% (this morning: 100%)

Right eye:

12pt: 74% (this morning: 76%)

18pt: 100% (this morning: 90%)

all others: 100% (this morning: 100%)

So there appears to be a little truth for me. Both 12pt numbers dropped a little, and I did notice a few more artifacts getting in the way.