About a year ago, I had a small cold and headache with the feeling
that the tubes inside my head were blocked. During that time, the left
side of my head hurt, and my left eye became bloodshot, as if
irritated. I awoke on several mornings to find my left eyelids stuck
together with hardened eye-juice.

That was a year ago. It only lasted a week, and I feel fine. However,
ever since then, my left eye has seemed more irritable than the right
one.  My left eye always looks a little redder and a little more tired
compared to the right one. So, for example, if I'm sleepy, the left
eye always looks sleepier than the right one. If I splash water on my
face in the morning, the left eye is the one that goes red. Why?

The difference is mostly comparative, I guess. The right eye makes the
left one look bad. But why, since then, has the left looked worse?

~Iain