Michelle Phan, a video blogger, shows Gaga enthusiasts how to use circle lenses.

Youtube

he obsession with all things Lady Gaga has touched the ophthalmology world with the disturbing popularity of "circle lenses" — unusually large contact lenses which give the wearer the big-eyed look Gaga sported in her "Bad Romance" music video. Doctors warn that the unregulated lenses, sold on the internet as cosmetic enhancements, could cause infections and lead to blindness. Is this "eyeball as accessory" trend taking Gaga-mania a step too far? (Watch an ABC report about "circle lenses")

How do circle lenses work?
Unlike standard contact lenses, which cover only the eye's colored portion (the iris), circle lenses extend slightly into the whites of the eye, creating the illusion of a larger iris. While you can buy circle lenses (at $20-30 a pair) that look plausible, they are also available in frankly fake neon hues and pseudo-mystical patterns. 

Did Lady Gaga actually wear circle lenses in the "Bad Romance" music video?
No. According to The New York Times, Gaga's gargantuan eyes were a computer-generated special effect. But that hasn't dissuaded wannabes; one YouTube tutorial teaching "little monsters" to achieve Gaga's look using circle lenses has received over 9 million page views.

Why are circle lenses more dangerous than normal contacts?
Since the website selling these products is flouting FDA regulations, customers are purchasing lenses without a proper prescription or fitting, leaving users susceptible to inflection and corneal tears — injuries which could lead to blindness. 

Sources: NY Times, Geekosystem, Stylelite