This didn't strike me as quite right, as we know that cephalopods have eyes similar to vertebrate eyes, yet wired the other way around. Clearly, there must be an engineering solution to the problem.
And, sure enough, there is. The analogous part of a squid's eye is located just below the photoreceptors, and is perfectly capable of providing sufficient nutrients and oxygen to these cells. They also appear to do so more efficiently than vetebrate eyes. In a vetebrate, the part of the cell directly facing the choroid is the photoreceptive cilia, not the main body of the cell itself, while in cephalopods this is the other way round. The energy producing reactions inside our cells are carried out by mitochondria, and so it is these, in the cell body, to which oxygen needs to be delivered. Vetebrate eyes not only have their light detectors facing away from the light, they have their engines facing away from most the fuel supply.
As for the argument that the choroid is necessary as a heat sink, this doesn't appear to be true at all. The choroid is a source of heat. About a quarter of the light that falls on the retina is caught by light-absorbing pigments in the choroid, and then radiated out as heat energy. What we have here is a heat source placed directly next to the heat-sensitive part of the retina, which necessitates the high-speed blood flow through the choroid, so as to carry some of this heat away.
This is mostly drawn from
this article on the Panda's Thumb website.
As a side note to Blzbub, it seems perfectly believable to me that slevesque never wears sunglasses. I never wear sunglasses, and I've never noticed this being particularly unusual. A quick straw poll of my flatmates reveals that only 50% (or two, depending on how you want to look at it) own a pair of shades.
Edited by caffeine, : Added note to Blzbub
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