As you know, I wear circle lenses and many other people do as well. A blogger that I follow recently posted an entry titled, "How Defective Circle Lenses Damaged My Eyes"
She didn't abuse her eyes in any way. She keeps her lenses clean and she doesn't over use them or anything. She was given defective lenses.
If you wear lenses or have been thinking about wearing them, please read this post and be careful of where you buy your lenses from. This isn't to scare you away or force you to stop, but to be very careful of your choices.
If you're unsure of where to buy from, you can talk to the people on this forum: The Official Circle Lens Thread on Gaia, or follow the blog of the thread owner, Occasionally Cute which majority of her posts are of circle lenses! She's an awesome person and very nice! But at the thread, they have a list of shops where people have bought from and even a list of shops where you shouldn't buy from. However, it's better to be cautious and to exchange emails with the owners if you're unsure of their products but want more information.
I've only worn lenses from Shoppingholics, Pinkyparadise, and Honeycolor for the years that I've been wearing them and have had no irritations except for when I personally decide to wear them longer than suggested or if my eyes are becoming dry.
Just make sure you clean your lenses properly. Renew the solution every time you use them and if not in use, renew them every month. Wash your hands thoroughly before handling the lenses. Make sure the lenses are properly cleaned so that there's no build up. Every one to three months either get new lens cases or thoroughly clean the cases. Use a solution and eye drops that's best for your eyes to reduce dryness, if any. Don't wear them too long or too often, your eyes need to breathe. Also, if you feel ANY discomfort at all, take them out immediately and check if there's anything on the lens such as a speck of dust or a tear in the lens. Don't force yourself to wear them until they're comfortable. It won't work. Take them out, clean them, let them soak over night if need be and try again. If they continue to be uncomfortable and you don't know why, just throw them away.
Remember, these are little pieces of plastic we're putting in our eyes. Regardless if they're regular lenses or circle lenses, take care of them, yourself, and make sure you're purchasing them from a good and honest company.