It is OK for you to use windex to clean your sunglasses lenses. Just follow the steps. Firstly, put your sunglasses under running water to remove the dirt and particles and then dry them with a piece of soft cloth. Secondly, spray your sunglasses lenses with windex, holding your glasses by the bridge. Thirdly, rub your sunglasses lenses gently but firmly with another clean soft cloth. Fourthly, clean ridges and crevices with a cotton swap soaked in Windex. At last, dry your glasses again. Remember not to apply to hot water to rinse your sunglasses.
In fact, I think you had better not clean your lenses with the windex. As we all know, there is a ingredient in the windex called the ammonia, which is very slightly acidic and can dissolve alkali metals, which is what your sunglasses lens coatings are made out of. Then some time later, the coating on the surface of your glasses will disappear and the result is that your sunglasses can protect your eyes from the sunshine. In other words, there is another product called situation and glasses cleaner, so I suggest you clean your sunglasses with the right thing, that's why the professor and experts created them. Now, maybe you will say that the situation and cleaner will cost you some money. Frankly, I think it will not cost you much money. Meanwhile, you can also have a try with the soap and warm water, which nearly cost you nothing.
You'd better not use the windex to clean sunglasses lenses. If the windex contains the acidity, it may damage the coating around the lenses. The principle is just like that acid rain to the sun umbrella. If you want to clean sunglasses lenses, the most safe and easy way is to use the clean water to wash it.