The iris is pigmented and opaque since it is a diaphram controlling the amount of light entering the eye.
(The iris; is pigmented; since it is a diaphram) (it; is; a diaphram controlling the amount of) (a diaphram; controlling; the amount of) (light; entering; the eye)
The iris it a diaphram light
is pigmented is controlling entering
since it is a diaphram
a diaphram controlling the amount of
the amount of
the eye