List of soft contact lens materials

FDA Classification of Silicone Hydrogels

Soft contact lenses are one of several types on the U.S. Market approved by the U.S. Food and Drug Administration[1] for corrective vision eyewear as prescribed by optometrists and ophthamologists.[2] The American Optometric Association published a contact lens comparison chart called Advantages and Disadvantages of Various Types of Contact Lenses on the differences between them.[3] These include:

Definition

The U.S. Food and Drug Administration (FDA) states that:

Soft contact lenses are made of soft, flexible plastics that allow oxygen to pass through to the cornea. Soft contact lenses may be easier to adjust to and are more comfortable than rigid gas permeable lenses. Newer soft lens materials include silicone-hydrogels to provide more oxygen to your eye while you wear your lenses.[4]

Types of soft contact lenses

The U.S. Food and Drug Administration (FDA) classifies soft contact lenses into four groups for the U.S. Market. They are also subcategorized into 1st generation, 2nd generation, and 3rd generation lens materials.[5] These 'water-loving' soft contact lens materials are categorized as "Conventional Hydrophilic Material Groups ("-filcon"):

Group Water Content Percentage Ionic/Non-Ionic
I Low Water Content (<50%) Nonionic
II High Water Content (>50%) Nonionic
III Low Water Content (<50%) Ionic
IV High Water Content (>50%) Ionic

Note: Being ionic in pH = 6.0 - 8.0". This chart was published in the FDA Executive Summary Prepared for the May 13, 2014 Meeting of the Ophthalmic Devices Panel of the Medical Devices Advisory Committee.[6]

The FDA has been considering updating soft contact lens group types and related guidance literature.[7][8][9]

Contact lens polymers (silicone hydrogel materials)

The materials that are classified in the four (4) FDA groups include the ones listed in the next 4 sections:[10][11]

History

The first contact lenses were made of a polymer called polymethylmethacrylate(PMMA) and became available in the 1960ss. Lenses made of PMMA are called hard lenses.[12] Soft contact lenses made of polyacrylamide were introduced in 1971.[12]

FDA groups and brands

Below is a list of most contact lens materials on the market, their water percentage, their oxygen permeability rating, and banufacturer brands.[13] Note that the higher the Oxygen Permeability rating, the more oxygen gets to the eye.

Group 1 - Low Water (<50% H20) Nonionic Polymers

Material % Water Oxygen Permeability (Dk) Brands
Teflicon 38 8.9 Cibasoft, Illusions, Torisoft
Tetrafilcon A 43 9 CooperToric, Preference, Preference Toric, Vantage
Crofilcon 38 13 CSI, CSI Toric
Hefilcon A 45 12
Hefilcon B 45 12
Mafilcom 33 4
Polymacon 38 9 Biomedics 38, Edge III, Z4/Z6, Soflens 38
Hioxifilcon B 49 15
Galyfilcon A 47 86[14] Acuvue Advance with Hydraclear, Advance for Astigmatism
Lotrafilcon A 24 140 Focus Night & Day
Lotrafilcon B 38 140 O2Optix / AirOptix
Senofilcon A 38 107 Acuvue Oasys
Samfilcon A 46[15] 163[16] Bausch + Lomb Ultra

Group 2 - High Water (>50% H20) Nonionic Polymers

Material % Water Oxygen Permeability (Dk) Brands
Surfilcon A 74 35
Lidofilcon A 70 31
Lidofilcon B 79 38
Netrafilcon A 65 34.5
Hefilcon C 57 ?
Alfafilcon A 66 32 Soflens 66
Omafilcon A 59 33 Proclear Compatibles
Vasurfilcon A 74 39.1
Hioxifilcon A 59 36 Definity 59%
Hioxifilcon D 54 21 Definity 54%
Nelfilcon 69 26 Focus Dailies, Dailies Toric
Hilafilcon A 70 35 Soflens 1-day
Hilafilcon B 59 22 Soflens 59

Group 3 - Low Water (<50% H20) Ionic Polymers

Material % Water Oxygen Permeability (Dk) Brands
Balafilcon A 36 ? Purevision
Bufilcon A 45 16
Deltafilcon A 43 10
Phemfilcon 38 9 Durasoft 2

Group 4 - High Water (>50% H20) Ionic Polymers

Material % Water Oxygen Permeability (Dk) Brands
Bufilcon A 55 16
Perfilcon A 71 34
Etafilcon A 58 28 Acuvue, Acuvue Bifocal, Acuvue 2, Acuvue 1-day
Focofilcon A 55 16
Ocufilcon B 53 16
Ocufilcon C 55 16
Ocufilcon D 55 19.7 Biomedics 55, Biomedics 55 Premier
Ocufilcon E 65 2
Ocufilcon F 60 24.3
Phemfilcon A 55 16 Durasoft 3, Freshlook, Wildeyes
Methafilcon A 55 18 Sunsoft Eclipse, Revolution, Sunsoft Toric
Methafilcon B 55 18
Vilfilcon A 55 16 Focus 1-2 Week, Focus Toric, Focus Progressives

Production generations

There are three generations of silicone hydrogel contact lens materials:[17]

1st Generation 2nd Generation 3rd Generation
Material: Lotrafilcon A, Balafilcon A Senofilcon A, Galyfilcon A Samfilcon A, Comfilcon A, Enfilcon A
Features: TRIS structures, plasma treated, high modulus Modified Tanaka monomer, lack of coatings, higher Dk for water content No TRIS structure, no surface treatments or wetting agents, breaks traditional water-Dk-modulus relationships

References

  1. ↑ Denise Hampton, Ph.D (13 May 2014). "Contact Lens Safety - Ophthalmic Devices Panel" (PDF). www.fda.gov. FDA Division of Ophthalmic and Ear, Nose and Throat Devices. p. 97. Archived from the original (Microsoft PowerPoint) on 18 Jun 2016.
  2. ↑ "About Contact Lenses - clma.net". clma.net. Contact Lens Manufacturers Association. Retrieved 18 June 2016.
  3. ↑ "Caring for Your Vision: Advantages and Disadvantages of Various Types of Contact Lenses". www.aoa.org. American Optometric Association. Retrieved 18 June 2016.
  4. ↑ Center for Devices and Radiological Health. "Contact Lenses - Types of Contact Lenses". www.fda.gov. U.S. Food and Drug Administration. Retrieved 18 June 2016.  This article incorporates text from this source, which is in the public domain.
  5. ↑ http://www.aalens.com/fda.html
  6. ↑ Ophthalmic Devices Panel of the Medical Devices Advisory Committee (May 13, 2014). "FDA Executive Summary Prepared for the May 13, 2014 Meeting of the Ophthalmic Devices Panel of the Medical Devices Advisory Committee" (PDF). U.S. Food and Drug Administration. p. 2. Archived from the original (PDF) on 7 Aug 2015. Retrieved 18 June 2016.
  7. ↑ LORETTA B. SZCZOTKA-FLYNN, OD, MS, FAAO (1 Feb 2005). "Contact Lens Materials: Advocating a New Lens Group". Contact Lens Spectrum. Contact Lens Spectrum - February 2005 Issue. Archived from the original (Journal Article) on 6 Oct 2015. Retrieved 18 June 2016.
  8. ↑ "Contact Lens Compendium". contactlensupdate.com. Contact Lens Spectrum. Retrieved 18 June 2016.
  9. ↑ Tina Kiang, PhD; Joseph Hutter, PhD; J Angelo Green, PhD; K Scott Phillips, PhD; Malvina B Eydelman, MD (10 Nov 2011). "Updating the Contact Lens Classification System" (PDF). www.fda.gov. http://www.fda.gov/cdrh/devadvice: FDA Center of Devices and Radiological Health. p. 38. Archived from the original (Microsoft Powerpoint) on 17 Nov 2011.
  10. ↑ "Contact Lenses: Manufacturing/Chemistry" (PDF). www.fda.gov. U.S. Food and Drug Administration. n.d. p. 25. Archived from the original (PDF) on 15 May 2015. Retrieved 18 June 2016.
  11. ↑ "Editorial - Should Silicone Hydrogels be Placed in a Separate FDA Soft Contact Lens Category?". www.siliconehydrogels.org. Retrieved 18 June 2016.
  12. 1 2 "Polymers in everyday things – Contact Lenses" (PDF). rsc.org. Royal Society of Chemistry. Archived from the original (PDF) on 19 June 2016. Retrieved 19 June 2016.
  13. ↑ "Contact Lens Materials: Water Content". www.aclens.com. aclens.com. Retrieved 18 June 2016.
  14. ↑ Dr. Karen French (12 May 2008). "The Performance of Galyfilcon A" (PDF). OpticianOnline.Net. Contact Lens Monthly. Retrieved 18 June 2016.
  15. ↑ AVID L. KADING, OD, FAAO. "New Lens Technology Targets Improved Vision and Comfort: Samfilcon A - Contact Lens Design & Materials". clspectrum.com.
  16. ↑ "Product Spectrum: Unsurpassed Comfort and Vision the Goal with Monthly SiHy Lens". clspectrum.com. Contact Lens Spectrum. Retrieved 18 June 2016.
  17. ↑ "Looking at Silicone Hydrogels Across Generations". www.optometricmanagement.com. Optometric Management. Retrieved 18 June 2016.
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