Keshav enters a dark room from a brightly lit area. He experiences difficulty in viewing objects, but gradually his vision improves.

Explain the role of the photoreceptors in this case.

Rhodopsin is the pigment which is responsible for vision in dim lights. It gets bleached in bright light. It takes a few seconds for it to regenerate in dim light. Then, the vision improves. Iodopsin responsible for vision in bright light does not function in dim light.