Charged particles hitting the retina?

Our Perfect Master spoke of charges hitting the retinaand causing them to “fire” off the rods or cones in the retina, which low earth orbiting astronauts see as flashes of light. But I recall the astronauts that went to the moon also saw flashes of light when they closed their eyes. The explanation trotted out back then was the result of Cerenkov light (particles that travel through a medium–in this case vitreous humor-- faster then than light can travel generates a kind of “light” shock wave) which in turn was picked up by the retina.

Or is there a different mechanism at work with respect to the South Atlantic anomaly?

Probably the same mechanism.

The key is that in both cases they have access to charged particles that cause the light flashes.

I think the point here is that the van Allen belts or charged particles tend to shield low earth orbit from cosmic radiation that causes problems - high speed particles can cause all kinds of havoc.

SO I gather the SAA is a spot where this protection is not so good, similar to the (magnetic) poles, where the filed dps into the earth and the protective powerr of the magnetic fields at altitude is much less.