MadSci Network: Anatomy
Query:

Re: Can you see your own cornea?

Date: Mon Jul 19 12:44:22 2010
Posted By: Tom Hancewicz, Sr. Scientist, Spectroscopy and Analytical Science
Area of science: Anatomy
ID: 1275525098.An
Message:

Even though a material may be clear, it can still be seen optically if the refractive index of the material is different from the air or surrounding material. The refractive index of the cornea is somewhere between 1.33 and 1.37 which makes it much higher than the surrounding air which has a refractive index is just a tiny amount greater than 1. Therefore when visible light travels from the surrounding air into the cornea at an angle other than zero it will be bent slightly allowing an observer to see it.

It is in fact easy to find you cornea by simply looking at your eye in the mirror. You will notice a clear surface covering the iris (the colored part of the eye) and pupil. This is the cornea. However, you don't actually see your own cornea when you use your eyes to look at other objects because you are looking through it at approximately zero angle and in the far-field (images are in focus far from the cornea). If you could see in near-field mode (near the cornea surface) you would be able to see a small distortion of the image due the refractive index difference at the surface and the large angles of incidence at near-field.

References:
http://www.medhelp.org/gov/cornea.htm
http://retina.anatomy.upenn.edu/~lance/eye/cornea.html


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