Translations:The Eye and Retina/5/en

The Iris and the Pupil

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The iris is the part of the eye located between the cornea and the lens. In the center of the iris is the pupil, which is an aperture that allows the light to enter the eye. The iris' muscles constrict the pupil when exposed to bright light, and dilate it when exposed to dim light. Melanin levels are one of the most prominent factors responsible for the color of the iris. When melanin is relatively absent, the iris will likely be blue or green, while when there is a lot of melanin, the iris will be more likely to appear brown or black.