The color of the Eyes

Jim Hutchins hutchins at
Fri Feb 17 14:01:37 EST 1995

Michael Liss        t3173 (c4549 at wrote:
: Well, I'm not exactly sure weather this is the right group for such a q
: question.  Here it is anyway:

: What is the stuff that gives the eyes their color?
: How can it be Blue/brown/green?
: Albinos have no color at all. So it must have something to do with
: the melanin pathway. 
: If you know what the chromophor is do you also know what protein it is 
: associated with?

: Anxiously waiting for an answer

: Mike

: Michael.Liss at

Eye color is due to the number and distribution of melanin-containing cells
called `clump cells' in the iris stroma.

The iris is built kinda like this:

      ======================    <- anterior epithelium (nearest cornea)
    /    *   *      *   *       \
  /   *        *     *    *      \
|       *        *     *         |  iris stroma with clump cells (*)
|   *      *             *      /
\     *        *          *    /
  \      *       *            
    \ *********************     } pigment granules in posterior epi. cells
     ======================     } posterior epithelium (nearest lens)

The `*'s represent the pigmented clump cells.  The pupil is to the left
of the page.

Albinos lack all pigmented cells in the iris, so the iris appears light pink
due to its blood supply.  (No *s are present at all).

Blue-eyed people have the posterior layer of pigmented cells, but not many
pigmented cells in the stroma.

Brown-eyed people have lots of pigmented cells throughout the stroma as well
as the posterior pigmented layer (like the picture shown).

Hope this helps


Jim Hutchins                    []     E-Mail: hutchins at
Associate Professor, Anatomy    []     Assistant Professor, Neurology
Univ Mississippi Med Ctr        []     Jackson, MS

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