Table 2.

Summary of Soft Contact Lens Groups, as Classified by the FDA

Group	Water Content	Polymer Type	Lens Material
I	<50% H2O	Nonionic polymer	Tetrafilcon A, Polymacon
II	>50% H2O	Nonionic polymer	Lidofilcon A or B, Alfafilcon A,
			Omafilcon A, Nelfilcon A,
			Vasurfilcon A, Hioxifilcon A
III	<50% H2O	Anionic polymer	Bufilcon A, Phemfilcon A, Ocufilcon A
IV	>50% H2O	Anionic polymer	Etafilcon A, Vifilcon A

Source: U.S. Food and Drug Administration.