The document discusses how the eyes continuously work to dilate and contract the pupils in response to changing light conditions. It describes how Cocoons fit-over sunglasses help create a "zone" of optical tranquility by fully enclosing prescription glasses and blocking unregulated light from entering from below, reducing eyestrain. Wearers of Cocoons report feeling more relaxed and needing their radial and circular muscles to work less hard compared to other fit-over sunglasses.