Many critics of intelligent design point to examples of obvious imperfections, such as the location of neural connections being in front of the photoreceptor cells, rather than behind the retina, and the formation of a blind spot because the neural wiring to the brain must poke through the retina to form the optic nerve. Why do these seeming errors exist?

There are practical considerations not being considered here. This is a functional solution to a series of problems involving fragility of the cellular architecture, the nature of the cell makeup involved in photoreception, and the ability to support it mechanically in addition to the neurological signaling required to transmit information from the impingement of photons on the photoreceptors themselves. It looks like a faulty patchwork of less than ideal planning and execution but, in fact, is a miracle of sorts including the seemingly illogic design element you describe. We would have to give you a quite detailed and lengthy lecture to defend this idea, but we assure you it is defensible, it is that people simply do not understand physiology, and cellular anatomy, and biochemistry sufficiently yet to understand the interplay of the energies at an electrical and chemical level impinging on cellular matter in a way to create the proper signaling and responses to the environment, and transmit the information intelligibly to the brain for processing, and have everything hang together and be efficient. In short, this is really a problem for another day when there is greater knowledge and sophistication in understanding the biology involved. We cannot jump out too far in front of you and fill in many blanks with information you, in a sense, have not developed, at least to a great extent, on your own, so there must be more deep thinking and cross‑fertilization of disciplines as well to find the root reasons for this odd anatomical array. This itself is quite a powerful clue, if people want to follow it, it will be rewarding, we assure you.