It wasn’t only their own nuclear bomb flash that they had to be aware of. They would be flying into an active war zone, with other bombers dropping their weapons on their own targets, missile warheads detonating, nuclear air-defence missiles going off, etc etc. The idea was that they would use the anti flash curtains to protect the rest of the crew, but the pilot had to be aware of what was going on outside and so his curtain would be pulled back far enough for this. However, he was also issued with an eye patch, so that if blinded in his uncovered eye he would still have a working one. If that was blinded in turn, he would hand over to the co-pilot, who also had an eye-patch…so there would have been a total of four eyes available to fly the mission.
Rumour has it that when they had dropped their bomb, and realising that the UK would by this time essentially be a pile of smoking ash, they would fly east until the fuel ran out, at which point the crew would bale out, and individually settle down to a nomadic life with an accommodating Mongolian woman.