Sunday, January 19, 2014

The Cornea

Cornea is a clear transparent and elliptical structure with a smooth shinig surface. the average diameter is 11-12 mm The thickness of the central part is 0.52 mm and the peripheral part is 0.67 mm. The central one third is known as the optical zone. The refractive index of cornea is 1.37. The diopteric power of cornea is approximately 43 to 45 dioptres. The cornea consists of fie layers namely 1. The epithelium 2. Bowman’s membrane 3. The stroma 4. Descemets membrane 5. Endothelium There are two primary functions of cornea. 1. It acts as a major refractory medium 2. It protects the intraocular contents.


  1. Thanks for the info! Reading this blog, particularly the part about the cornea being the major refractory medium of the eye, has brought back up a question I've had since I was a child. Is the cornea structure in a cat's eye different? And, if so, is this the reason for cat's eyes appearing to glow? It would be logical that structural differences in the refractory medium would result in a difference in the amount and appearance of refracted, as well as reflected light.

  2. yes the structural differences in the refractory medium do cause changes in the overall appearance of the object for the on looker.
    In the cat's eyes case however, its the response of their retina to the light thrown into their eyes in the dark. These animals only have dark image perception and the glow in their eyes has something to do with the great excess of rods in their retina.

  3. Very informative post about the cornea, thank you! I had wondered the same thing about cats’ eyes also. So thank you for explaining that! I enjoy reading your posts:) The resent information about eye structure and different diseases is very interesting.