I've been having a bit of eye strain, and since my eyeglasses are old, I made a trip to the optometrist to get a new prescription. I was stunned when he told me the problem... my eyesight has improved, so my eyes are straining with glasses too strong for them.
I've been wearing glasses since I was in the third grade, and each time I purchased new frames, it was always with stronger prescription lenses than the ones before. (Thank goodness for modern lightweight, thin, plastic lenses because mine would look like coke bottle bottoms if I had to use the old time "glass" glasses.) As my near-sightedness increased over the years, sometimes the change was slight, but it was always for the worse, and never the better.
So I find it interesting that after a year of eating healthier and striving to avoid processed foods, my eyesight improved. Coincidence? Maybe, but... I clearly see another reason to keep eating healthy!