Visual phenomenon while flying

I was recently sitting in a window seat on the left side of a plane. The sun was to the left and perpendicular to the plane, and the sunshine was hitting me on the left side of my face. I was reading at the time, and noticed that if I closed my left eye, the page looked normal, black type on white paper. But if I closed my right eye, only seeing through the eye that the sun was shining on, I saw red type on white paper. Can someone explain this?

WAG: When the sun shines that bright, right into your eyes, you can actually see your retinas. If you’ve ever had a doctor shine a bright light in your eyes, you know what I’m talking about, and you know they’re kind of reddish with veins all over the place. So when you’re looking at something black, and your eyes are getting no input from the external world, you just see the red. Again, this is a WAG.

But my eyes *were *getting input from the external world. I was still able to read with that eye, except that I perceived the type as being red. And the sun’s light was entering from the side, not from straight-on.