Table 2.

FDA Classification of Soft CL Materials for Lens-Solution Interaction Testing

Group	Characteristics	Example of Lens	Comments
I	Low Water (<50% H2O) Nonionic Hydrogel	Polymacon (38%) (Dk = 9)	Lowest rate of protein deposit formation of hydrogel materials due to non-ionic surface properties. low Dk
II	High Water (>50% H2O) Nonionic Hydrogel	Omafilcon B (62%) (Dk = 34)	Heat disinfection, preservatives sorbic acid and potassium sorbate should be avoided
III	Low Water (<50% H2O) Ionic Hydrogel	Deltafilcon A (43%) (Dk = 10)	Higher rate of protein deposit formation due to ionic surface properties. low Dk
IV	High Water (>50% H2O) Ionic Hydrogel	Etafilcon A (58%) (Dk = 28)	Highest rate of protein deposit formation of all groups. Heat disinfection, preservatives sorbic acid and potassium sorbate should be avoided
V	Silicone Hydrogel	Lotrafilcon B (33%) (Dk = 110)	Soft materials that have a Dk value greater than 30, which is not explained by their water content