What do red-eye correction and anti-red-eye lamp of digital camera mean?

The red-eye phenomenon of flash photography is that people's pupils are wide open in the dark, and the flash directly shoots into the pupils, illuminating the retina with rich blood vessels, showing that the pupils are red. Red-eye correction is to convert the red-eye of a picture that has been shot as red-eye into brown-black to eliminate the red-eye phenomenon. Anti-red-eye flash is to add pre-flash before shooting, stimulate the pupil to contract quickly with strong light, and flash again without illuminating retinal blood vessels. The former is a remedial measure and the latter is a preventive measure.