What happens to the eye when you enter a darkened cinema hall from bright sunshine? Give reason for your answer.

As we enter a darkened cinema hall from bright sunshine, at first we cannot see anything clearly. But in no time, our vision improves. This is because outside the cinema hall, the intensity of light entering the eye is large, so the iris makes sure that the pupil is small. But when we enter the cinema hall, the pupil expands making more room for light making things visible.