For chickens don’t know how useful it is
https://pubmed.ncbi.nlm.nih.gov/15529996/
For humans but might still help, it has a bit on inheritance
https://medlineplus.gov/genetics/condition/coloboma/#inheritance
I don’t know anything about it. but if you are worried about it being hereditary then I would advise not to breed her, if it is recessive then it will be hard to get ride of later down the line, it is best to breed only from healthy normal animals.
I don’t breed duck so anyone who knows more...