"One of the tired old canards on which antitheists have dined out for years is the claim that our eye is stupidly wired back to front, something no decent designer would use. E.g. the vociferous misotheist and eugenicist Clinton R. Dawkins said in his famous book, The Blind Watchmaker:
“Any engineer would naturally assume that the photocells would
point towards the light, with their wires leading backwards towards the brain. He would laugh at any suggestion that the photocells might point away, from the light, with their wires departing on the side nearest the light. Yet this is exactly what happens in all vertebrate retinas. Each photocell is, in effect, wired in backwards, with its wire sticking out on the side nearest the light. The wire has to travel over the surface of the retina to a point where it dives through a hole in the retina (the so-called ‘blind spot’) to join the optic nerve. This means that the light, instead of being granted an unrestricted passage to the photocells, has to pass through a forest of connecting wires, presumably suffering at least some attenuation and distortion (actually, probably not much but, still, it is the principle of the thing that would offend any tidy-minded engineer). I don’t know the exact explanation for this strange state of affairs. The relevant period of evolution is so long ago.”
Other anti-creationists such as Kenneth Miller parrot the same sort of argument.
However, ophthalmologists have denounced Dawkins’ claim repeatedly. E.g. George Marshall, the Sir Jules Thorn Lecturer in Ophthalmic Science, stated in reply to Dawkins:
“The idea that the eye is wired backward comes from a lack of knowledge of eye function and anatomy.”
Dr, Marshall explains that the nerves could not go behind the eye,
--because that space is reserved for the choroid,
--which provides the rich blood supply needed for the very metabolically-active retinal pigment epithelium (RPE).
--This is necessary to regenerate the photoreceptors,
--and to absorb excess heat.
*So it is necessary for the nerves to go in front instead.
It’s important to note that the ‘superior’ design of Dawkins with the nerves behind the photoreceptors would require either:
The choroid in front of the retina—but the choroid is opaque because of all the red blood cells, so this design would be as useless as an eye with a haemorrhage!
Photoreceptors not in contact with the RPE and choroid at all—but the photoreceptors would be slow to regenerate, so it would probably
Another creationist ophthalmologist, Dr Peter Gurney, in a detailed article, pointed out all the above with the RPE, but pointed out another use: extracting excess heat.
CMI
