Image edited from source at Britannica

The eye (any eye) is a miracle of evolution, which has filled its structure at every scale with an apparent intentionality that is the hallmark of complicated systems under intensive selective pressure. It is very much possible to look at almost every design feature and state a compelling reason why it's there, which makes it a rich place for the engineering-minded to find fun little design features.

This post is meant to discuss topics that are less frequently discussed elsewhere, and not often discussed in introductory courses, rather than anything that can be quickly gleaned off of common summaries. Another way to describe it is that I intend to dive a bit into the kind of fridge-logic questions you might come up with randomly after opening the evolutionary eye-fridge, particularly the ones that turn out to have interesting answers.

As such, this post is going to be a bit of a grab bag of topics, rather than a focused point-by-point breakdown of the eye. I’m still going to group topics broadly into general categories, just for organizational reasons.