FDA classification of soft contact lens

four types of soft contact lens materials based on FDA classification

1. FDA Classification of soft contact lens By: sushmitha hebri

2. The U.S Food and Drug Administration(FDA) has classified soft contact lens materials according to their water content and ionic charge. The groups were initially designed to deal with how different lenses interacted with various lens care products and to differentiate between lenses which attracted varying amounts of protein deposits from the tear film. This classification simplifies the large number of possible soft lens materials into few groups

3. Group 1: Low water content, non-ionic polymers Group 2: high water content, non-ionic polymers Group 3: low water content, ionic polymers Group 4: high water content, ionic polymers

4. Ionic lens surface is ‘charged’ (usually negative) Non ionic lens surface is ‘neutrally charged’ or no charge. The main reason to have an ionic surface contact lens is to attract water into the lens ,thus older high water content are ionic. Advantage of having ionic lens is , it is easier to wet the contact lens. Disadvantage of having an ionic surface is that deposits may adhere to the lens more readily .

5. The groups and their features are listed in the table below : Group 1 Low water , Non-ionic Group 2 High water , Non-ionic Group 3 Low water , Ionic Group 4 High water , Ionic Lowest protein deposition Lower protein deposition Lower protein deposition Highest protein deposition Eg: B+L iConnect Annual B+L Optima 38 Eg: B+L Softlens 59 B+L Softlens daily disposable Eg: B+L Purevision 2 Eg: JnJ Acuvue lenses