Fair enough Stewart, but I did not get the impression that this "black-eyed" fall looked very much like a brain rattler rather than an eye rattler. You are of course correct that I was jumping to conclusions. I simply am inclined to think of optical rather than cranial effects in such cases, partly because I think that suitable blows or changes in blood pressure affecting the eye would be commoner than those affecting the brain in general, including the visual cortex in particular.

What is more, I suspect (without substantial support) that most blows powerful enough to cause phosphenes in the cortex might well be powerful enough also to cause phosphenes in the retina. Do you happen to know of any work that differentiates between these two classes of effect or gives any indication which is commoner?

Of course, at least one kind of visual disturbance in the brain does affect some people painfully commonly, as a result of cranial blood vessel contraction and perhaps the associated pressure changes, without any mediation of a blow: migraines.

I happen to be the fortunate host to very occasional migraines that most migraine sufferers would contemptuously deny to be migraine at all: as far as they are concerned migraines are crippling, nauseating, agonising attacks that last a day or two. Mine are mild, monolateral or bilateral, wriggling arcs of jagged light patterns that start round about the focal point, making reading difficult, then migrate outwards till they vanish some 20 min later. No pain, no nausea. What a luxury!