I should point out that, uncorrected, I am legally blind myself but I fly airplanes for a living. So no, I don't think being legally blind should inherently disqualify you from gun ownership or carrying.
However, it would make sense to me to bar someone from publicly carrying a weapon if they aren't correctable past the "legally blind" threshold. Such a person cannot properly identify targets or ensure they aren't endangering bystanders. I can barely walk around my apartment without the contacts in.