What is the ruling on divorcing the wife and paying the deferred mahr, or keeping her despite not having children, if the husband discovers that her visual impairment is 5 diopters instead of 3 as she stated before marriage, and he fears this will be passed on to their children?

Poor eyesight is not a defect that permits annulment of the marriage, and the wife is entitled to the full mahr (dowry), and the husband is not allowed to reclaim it. Divorce is disliked when there is no need for it. Procreation is a right for both spouses together, and neither of them is permitted to deprive the other of it except by mutual agreement.