Other Comments on Red Eye Reduction
Using a mask and selectively darkening the pupils, we have gone from the picture on the left to the one on the right below.
As you can see, darkening the pupils really improves the picture. As an aside, I sharpened the image on the right before finishing, and it also helps the photo (look at the fur, and the writing on the collar).
The photo above did not have a real severe case of red (green) eye. Check out the before-after photos below, which start from a more severe case of reflection from the eyes.
I used the same process as above. This demonstrates that it will work on a quite severe case. Notice though that the process retains the flash highlight. Take a look at an alternative method below.
In this photo, I used the mask to drop everything to pure black. This is equivalent to simply painting pure black over the pupils, which I have seen some do. Notice how less attractive the image looks without the flash highlight (personally, every photo I see like this makes the subject look evil). So, whatever mechanism you use, leave (or put in) a lighter area for the flash highlight. It really does make a difference.