“How the eye works”

Today in my physics class, we learned, among other topics, how the eye works.  Before I share what I was taught, I want to show a quote from Liberman’s book (pg. 18) that I was reminded of:

I was taught that vision is a mechanical function that works just like an optical lens — a “camera” in the eye.  In my textbook, the chapter on the optics of the eye was preceded by a chapter on general optics.  First we learned how light moved through lenses and prisms, and then we applied this to the vision process.  In fact, we studied the eye as if it were a camera that just happened to be located in the head.

The book’s copyright is in 1995, so Liberman must have learned that information over 13 years ago.  Now, over a decade later in 2008, I learned the following:

• The current chapter (Chapter 24)  we are learning from is on the combination of lenses and how light rays move through them.  Section 24.2 was on the camera.  Section 24.3 was on the eye.
• We learned that the lens is at a fixed distance from the retina.  This is the major difference between a camera and an eye; while a camera’s focus is changed by moving the lens, an eye’s focus is changed by changing the shape of the lens.  Cameras and eyes are similar because they both have a converging (plus) lens and a film/retina that the light rays are captured on.
• Then we learned the terms near point, far point, and the equation for the refractive power of a lens (measured in diopters).  Additionally, we learned about how light rays hit the retina in a normal eye, a myopic eye, and a hyperopic eye.

Wow, science has advanced so far in the mechanics of the eye in the past decade! 🙄 Anyway, I just thought I would share this information in case anyone wanted to know what is currently being taught on how the eyes (do not) work.