I have noticed remarkable shifts in the ability of my eyes to focus for reading.
When last I was eating a lot of bread and cheese, my eyesight deteriorated
so badly that I had to use 1.0 specs to read anything.  Since eating for my
blood-type, I can now read newprint most days without specs.
(small stuff I need to use a magnifying glass tho).  I am convinced that
diet can play a big part in the functioning of eyes!

Lynton