What are the structural differences between an eagle’s eye and the human eye that make them seeing so much better?

07 Dec What are the structural differences between an eagle’s eye and the human eye that make them seeing so much better?

All animals have evolved visual systems that maximize their likelihood to pass on their genes to succeeding generations. For animals that are often prey (e.g. frogs and many fish), having the very widest field of vision is highly important to minimize the risk of getting eaten by predators sneaking up from behind or the side. So their eyes are typically on either side of their head, with very little overlap in front. This provides an extremely wide field of vision even if there is little stereo or detailed vision.

Predators such as birds of prey depend for their survival on getting enough food by surprising those frogs and fish. Not being threatened as much by other predators up the food chain, evolution has provided birds of prey with both eyes facing forward for maximized distance and depth perception. The ” high-definition” photoreceptors of the eye are called cones (rods are for peripheral vision). Cones are far more numerous and closely packed in eagles than in humans (or most other mammals). Unlike rods in the retina, cones vary in structure with some being more sensitive to certain wavelengths than others (color perception). While the human macula is densely packed with cones, we can at best differentiate detail only to about 20/10 acuity (an even that is rare and found in young people). The eagles’ eye has a much deeper macula with even more densely packed cones than ours. Some of these are even sensitive to wavelengths we cannot perceive (infrared and ultraviolet).

So as much as we would all like to have “Eagle Vision” the differences in the anatomy of our eyes makes that unlikely, even with such advanced new technology as LASIK and IOLs!