It is, but we have to live in the real world and no right is absolute. We rightfully infringe on someone who is incarcerated, but nowhere does it say "unless they are in prison". Nowhere does it limit us to small arms, or even conventional arms, but I'm pretty sure you don't want me having Sarin at my house. Reasonable people can draw the line in different places, and I'm fine with legally blind people having a handgun permit, but we must put serious thought into where the line is placed.
This is the usual anti-gun mantra, you don't want me to have nukes, you don't want me to Sarin, do you? It's absolute nonsense, a blind person having a gun is not a danger by them merely having it any more than it is for a sighted person to have it. If your blind you're subject to the same laws regarding intentional or negligent misuse. If blind or sighted misuse their gun, punish that, everything else is simply incremental gun banning by setting arbitrary limits on ownership and possession and substituting the judgment of the state for the judgment of the individual.