This feature already exists:
RickHeath wrote:In the meantime using circle regions (don't forget to create a layer first if you're new to ASP/Bibble) that fit the red eyes reasonably closely and with a small feather (in a test shot I tried just now to check in ASP, I used 56 pixels with 8 feather on an 18MP image). I find that reducing exposure of the layer by 1-2 stops and decreasing the saturation to -50 to -75 gives good results.
1 layer, 2 circle regions and a reduced saturation is all you need.
The only trick a plugin could add here is the automatic detection of red eyes.