The tiny babies can catch up with good nutrition! You could give them things like banana, baby rice cereal, baby food, dog food, chicken, tuna, boiled egg.... lots of good fat and a little extra protien to their regular diet.
I would consider removing the odd eyed boy from your breeding program (and related offspring). The gene that causes this.. also causes mega colon. Basically the lighter eye is lighter because the gene stopped pigment working in that area. The same for any white areas on the body. In about 90% of cases the gene affects the insides of the rat as well, mega colon is basically where their intestines don't work and they can't process food or poop right. You will notice these babies, they are sickly looking they don't thrive like the other babies.. they look bloated and their death is very painful for them.
Here is a link for more info on Megacolon:
Health Guide: Megacolon
Link about the genes + mega colon:
White blazes and megacolon
Pic of a litter of babies, the ones with mega colon are obvious. The other babies in the litter have a 50% chance of getting late on set mega colon when they are 10 months or older.
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