How could 'red eye' be removed from photos?

Get closer to your subject so that the angle of reflection is more than 2.5 degrees. To do this, just memorize the ratio 1/12. So if the lens-flash separation is 2 cm, the camera-subject distance should be 24 cm or less, i.e. about 1/4 of a metre. If the lens-flash separation is 3 cm, the camera-subject distance has to be 36 cm or less, so on and so forth.