I googled just now and find out there is some products of sunglasses with transparent lenses. And I can see this kind of products in movies that the hero wearing a pair of glasses which can turn dark automatically as he walked into some bright circumstances. There are some such products, but they are not familiar to us and they are not so popular. Contact lenses are transparent, and they can also provide protection from UV radiation to some extent. But they are not as good as sunglasses. Actually sunglasses with various colored lenses are more fashionable and cooler. Brown lens is the best choice recommended, because it could provide 100% protection from UV rays. Grey is a fashionable choice, and it also can provide fully protection too. If I were you, I would rather choose sunglasses with colored lenses.
As you know sunglasses are made with colored lenses. To some extent, they are transparent so as you can see things through the lenses. And today, there are two types of sunglasses. one type is made of full tinted lenses. The sunglasses looks great and very cool especially some black sunglasses. They can reduce intensive light when you wear it. The other type of sunglasses are made of gradient tinted lenses. Usually, the lenses are darker in the upper part of lenses and gradually to be transparent at the button of the lenses. The purpose of the sunglasses is to protect the eyes fron intensive sunlight, at the same time, allow you see things more clearly through the button part of lenses. So, most of people prefer sunglasses with gradient tinted lenses.
The material of the sunglasses is special which could prevent your eyes from the uv rays in the strong sun lights. Some sunglasses are made with transparent. And other sunglasses are made with translucent character. But their colors of the glasses are various which offer you a lot of choices. The sunglasses now are regarded as the accessories to improve their looks. Their role is so important in summer.
It's hardly to say they are transparent or translucent. I've seen some sunglasses at Walmart and found some of them are much clear, while others seem to be translucent. Later, I hold consult with a sunglasses retailer and he told me that it depends on the darkness and materials. But most of them are translucent. The difference between transparent and translucent is transparent means allowing the views of objects on the other side, while translucent blocks objects on the other side. Glasses can absorb lights, but not all lights are good to eyes. Then sunglasses are created. Some scientists found that translucent sunglasses can prevent harm lights from sun shine. And sunglasses help with enhancing one's outlook. People who do not have near sight also want to wear eye glasses. Thus sunglasses just satisfy them.