As noted previously by another comment, there are several factors that must be taken into account in determining the effectiveness of nuclear weaponry. I'll try and keep this as general and simple as possible.

First, of course, is the blast radius, which is dependent on a multitude of complexities. For example, and aside from yield factors (arguably the most important and unfortunately the data we cannot accurately determine), it is reasonable to believe that most nations with nuclear weaponry and deployment capabilities will set the detonation to occur in the atmosphere over the target area. This is for a number of reasons, but mainly to avoid large scale fallout spread and global contamination (wind carries irradiated particles) and to maximize the EMP blast. From that statement, we can implicitly deduce additional fallout factors to add to our analysis, such as wind speed, direction, and obstructions. One way the United States, Russia, China, and more recently, North Korea have avoided fallout concerns is to eliminate surface contamination and wind variables altogether: subterranean detonations. When the boom boom is under a quarter mile of dirt and rock, fallout concerns will be nowhere near what they would be with a surface or atmospheric detonation. Although it's not a perfect system and there is no guarantee of containment, what happens is the earth surrounding the device is vaporized, leaving a crater at the surface. If you would like, you can look at Google Earth and see multiple crates is the southwestern portion of the US, localized mainly around White Sands, falling east of Groom Lake (If I remember correctly). It may be easier to just google "trinity test site" and see where that takes you.

I'm getting ahead of myself here, but blindness from nuclear detonation is wholly dependent on one's proximity to zero and line of sight to the detonation.

Long story short, nuclear detonations are most certainly survivable depending on one's proximity to the blast and any interfering obstructions. The initial heat blast decays rapidly and the following shockwave has a limited range as well. It's also important to note that the heat blast and shock wave are not "instantaneous" and have a velocity. Thus, depending on one's proximity to the detonation, it is possible to seek shelter before either hits you.

As for fallout from the detonation, it depends. Assuming the detonation was a surface detonation, blasting tons of irradiated particles into the atmosphere, mass extinction over time is a real possibility. I'm off on a tangent. I'll come back if anyone wants to get into this. I'm starting to think OP is right and the raiders/gunners/minutemen/BOS/ghouls/etc we all fight against are figments of the Sole Survivor's swollen, irradiated, and cryogenically frozen subconscious. We never woke up.