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Hydrophilic Materials Facts

Methyl methacrylate/Vinyl pyrrolidone

KEY DATES - MMA/VP

  • 1969 - 1972 First recorded work on MMA/VP polymers in US and UK       
  • Mar 13 1972 -  Frankland, Highgate & Cordrey, file UK Pat -  CLM/Special Polymers
  • Apr 73 - Jun 76 - Frankland & Highgate publish US/UK patents -    IH Laboratories and Duragel
  • Nov 4 1980 - Patel & Da'Costa publish UK patent - Igel

KEY PRODUCTS - MMA/VP

  • 1970 - Sauflon - Materials and Lathe cut lenses
  • 1973 - Duragel - Materials
  • 1975 - Scanlens 75 (Ciba) - Lathe cut lenses
  • 1986 - Titmus (Ciba) - Lathe cut lenses
  • 1981 - Polymeric Sciences/Biogel - Materials
  • c1983 - Coopervision (PBH) - Permaflex - Cast moulded
  • c1980 - Igel - Materials and lathe cut lenses
  • c1984 - Lunelle (Essilor) - Lathe cut lenses
  • c1984 - MJS (Essilor) - Cast moulded
  • c1992 - Precision (Aspect) - Cast moulded

Current  situation - MMA/VP

In 1991 the British Standard BS 7208: Part 2 was published. This is a generic classification for the materials used to manufacture contact lenses.  The group filcon 4 is reserved for materials made from MMA/VP and their chemically related species. An additional notation a or b is specified to indicate whether the material is non-ionic or ionic. Almost all these materials are non-ionic (they do not need to be otherwise!) and are given the name filcon 4a. An examination of the Contact Lens Yearbook for 1993, shows that practically every supplier of soft lenses listed has a material of this description, including the following:

  • Allergan Hydron - Omniflex 70 - Lathe cut -  Hydron H67 - Lathe cut
  • Aspect - Supergold - Cast moulded
  • Bausch & Lomb - B&L 70 - Lathe cut
  • Cantor & Silver - Focus 60 , Hydrofit 55/74, Software 58, Focus 80, Sauflon PW - Lathe cut
  • Ciba Vision - Scanlens 75, Weicon CE - Lathe cut
  • Contact lens Precision Labs - SP80,PX70,SP70,SP60 - Lathe cut
  • Eyetech - Eurosoft 70,77,85, Cleargel 75 - Lathe cut
  • Igel - Igel 58,67,77 - Lathe cut
  • Lunelle - Sunsoft  55 - Lathe cut & Spun cast , Cristelle - Cast moulded, ES70 - Lathe cut
  • Madden & Layman - REL 65 ,75 - Lathe cut
  • MJS Scientific - Seelite 73 - Cast moulded
  • Nova - Soft 60,Hanita AGE 58 - Lathe cut
  • Pilkington BH - Permaflex 74 - Cast moulded, Polysoft 70 - Lathe cut
  • Revision - Revision 62,70 - Lathe cut
  • David Thomas - Hi-soft,Ledasoft 65,80 - Lathe cut
  • Wesley Jessen - Durasoft 3 - Lathe cut
  • Wohlk - W50D, Weflex 55, Geaflex 70, G72D - Lathe cut

In addition many of these suppliers and others will supply prescription specials, torics, bifocals, tinted and UV blocked versions. Some of these have been approved by the FDA in the US and include - Permaflex, Scanlens, Sauflon. There are also many US only products which are approved and which are based on MMA/VP polymers.

The history of the MMA/VP lenses spans more than 20 years throughout the world. The market for low water content lenses continues to decline in favour of high water. High water lenses are made from MMA/VP or from modified pHEMA. Modified pHEMA's, including the worlds largest selling lens, Johnson & Johnson Accuvue, achieve high water content by the inclusion of ionic components which compromise chemical and physical stability. Therefore for water contents of above 65%, almost all contact lenses available are made from MMA/VP copolymers. Their stability has enabled satisfactory daily handling and care with any system, in particular peroxide disinfectants which are generally the safest and most effective.

With regards numbers of MMA/VP lenses, one can only guess in the order of ten million over the last 20 years. Currently MJS, PBH and New Focus are cast moulding in excess of one million lenses per year of MMA/VP lenses into the frequent replacement market, and each claims to be increasing their production.

2007 Andrews Wright Ltd.

Examples of hydrophilic types:

AEP 40
Low water absorption and swell with maximum mechanical stability and dessicant action.

AEP 50
Most used for encapsulation of other chemical materials for preservation and controlled release.

AEP 60
Most used for moulding and mechanical devices with best combination of mechanical stability and volume expansion.

AEP 80
High volume expansion and water absorption used for wound care and similar applications

Biogel
Contact lens and implant materials are available in a range of water contents from 61% to 78% and with linear expansions from 1.39 to 1.67.

AEP blends
Blended formulations are made using a combination of proprietry and/or commercial materials for the manufacture of a range of products.