WHY IS IT IMPORTANT TO STORE YOUR SUNGLASSES IN A CASE?
A pair of sunglasses is a fragile object that you won't always be wearing.
A glasses case allows you to store them at the end of the day or when the light level decreases, to maintain their condition as long as possible.
When you are not wearing your glasses, they must be protected to avoid scratches to the lenses and to maintain their protective features. The frame also needs protecting from impacts and deformation.
You can of course damage your sunglasses when wearing them, but it is more often when storing them that the risk of damage is the greatest. A case therefore proves essential for transporting them.