How does the iris impact vision?

The iris plays a crucial role in vision by adjusting the size of the pupil, which is the opening through which light enters the eye. By varying the size of the pupil, the iris controls the amount of light that reaches the retina, where the image is formed. In bright light conditions, the iris contracts to make the pupil smaller, reducing light intake and protecting the sensitive structures of the eye. Conversely, in dim lighting, the iris expands the pupil to allow more light to enter, enhancing visibility.

This function is essential for providing the appropriate level of light for optimal vision in different environments. The ability to control light intake helps to ensure that the retina is not overwhelmed by too much brightness, which could lead to discomfort and potential damage.