List of soft contact lens materials
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:
- soft contact lenses
- rigid gas-permeable (RGP)
- daily wear
- extended wear
- disposable and
- planned replacement contact lenses.
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 (hydrogel and silicone hydrogel materials)
The materials that are classified in the 5 FDA groups include the ones listed in the next 5 sections:[10][11]
History
The first contact lenses were made of a polymer called polymethylmethacrylate (PMMA) and became available in the 1960s. 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 manufacturer brands.[13] Note that the higher the oxygen permeability rating, the more oxygen gets to the eye.
Group 1 - Low Water (<50% H₂O) 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 | Alden SE, Miru |
| Galyfilcon A | 47 | 86[14] | Acuvue Advance with Hydraclear, Advance for Astigmatism |
| Lotrafilcon A | 24 | 140 | AirOptix Night & Day |
| Lotrafilcon B | 33 | 138 | O2Optix / AirOptix |
| Senofilcon A | 38 | 107 | Acuvue Oasys |
| Samfilcon A | 46[15] | 163[16] | Bausch + Lomb Ultra |
Group 2 - High Water (>50% H₂O) 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, Biomedics Extra, Aveo |
| Vasurfilcon A | 74 | 39.1 | |
| Hioxifilcon A | 59 | 36 | ExtremeH2O 59%, Aura ADM |
| Hioxifilcon D | 54 | 21 | ExtremeH2O 54% |
| Nelfilcon | 69 | 26 | Focus Dailies, Dailies Toric |
| Hilafilcon A | 70 | 35 | Soflens 1-day |
| Hilafilcon B | 59 | 22 | Soflens 59 |
| Nesofilcon A | 78 | 42 | Biotrue |
Group 3 - Low Water (<50% H₂O) Ionic Polymers
| Material | % Water | Oxygen Permeability (Dk) | Brands |
|---|---|---|---|
| Balafilcon A | 36 | 112/130 | Purevision, Purevision 2 |
| Bufilcon A | 45 | 16 | |
| Deltafilcon A | 43 | 10 | |
| Phemfilcon | 38 | 9 | Durasoft 2 |
Group 4 - High Water (>50% H₂O) 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 Moist, Acuvue Define, Colornova, Discon, Waldo, Natural Vue |
| 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 | Expressions Colors, Frequency 55, Hubble, Revolution, Sunsoft Eclipse, Sunsoft Toric, Vertex Sphere, Vertex Toric |
| Methafilcon B | 55 | 18 | Frequency 55 Toric |
| Vilfilcon A | 55 | 16 | Focus 1-2 Week, Focus Toric, Focus Progressives |
Group 5 - Silicone Hydrogel Polymers
| Material | % Water | Oxygen Permeability (Dk) | Brands |
|---|---|---|---|
| Delefilcon A | 33-80 (water gradient) | 140 | Dailies Total1 |
| Narafilcon B | 48 | 55 | Acuvue TruEye (old) |
| Narafilcon A | 46 | 100 | Acuvue TruEye (new) |
| Stenfilcon A | 54 | 100 | MyDay |
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
- ↑ 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.
- ↑ "About Contact Lenses - clma.net". clma.net. Contact Lens Manufacturers Association. Retrieved 18 June 2016.
- ↑ "Caring for Your Vision: Advantages and Disadvantages of Various Types of Contact Lenses". www.aoa.org. American Optometric Association. Retrieved 18 June 2016.
- ↑ 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.
- ↑ http://www.aalens.com/fda.html
- ↑ 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.
- ↑ 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.
- ↑ "Contact Lens Compendium". contactlensupdate.com. Contact Lens Spectrum. Retrieved 18 June 2016.
- ↑ 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 (PPT) on 17 Nov 2011.
- ↑ "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.
- ↑ "Editorial - Should Silicone Hydrogels be Placed in a Separate FDA Soft Contact Lens Category?". www.siliconehydrogels.org. Retrieved 18 June 2016.
- 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.
- ↑ "Contact Lens Materials: Water Content". www.aclens.com. aclens.com. Retrieved 18 June 2016.
- ↑ Dr. Karen French (12 May 2008). "The Performance of Galyfilcon A" (PDF). OpticianOnline.Net. Contact Lens Monthly. Retrieved 18 June 2016.
- ↑ AVID L. KADING, OD, FAAO. "New Lens Technology Targets Improved Vision and Comfort: Samfilcon A - Contact Lens Design & Materials". clspectrum.com.
- ↑ "Product Spectrum: Unsurpassed Comfort and Vision the Goal with Monthly SiHy Lens". clspectrum.com. Contact Lens Spectrum. Retrieved 18 June 2016.
- ↑ "Looking at Silicone Hydrogels Across Generations". www.optometricmanagement.com. Optometric Management. Retrieved 18 June 2016.