List of soft contact lens materials
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Soft contact lenses are one of several types of contact lenses for corrective vision eyewear as prescribed by optometrists and ophthalmologists.
Background
In the US market, soft contact lenses are approved by the US Food and Drug Administration. 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. These include:
- soft contact lenses
- rigid gas-permeable (RGP)
- daily wear
- extended wear
- disposable
- planned replacement contact lenses.
The US Food and Drug Administration (FDA) defines soft contact lenses as:
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.
History
The first contact lenses were made of glass, in 1888. Initially the glass was blown but soon lenses were made by being ground to shape. For the first fifty years, glass was the only material used. The lenses were thin, yet reports of injury were rare. In 1938 perspex (polymethylmethacrylate, or PMMA) began to replace glass in contact lens manufacture. PMMA lenses were easier to produce so the production of glass lenses soon ended. Lenses made of PMMA are called hard lenses. Soft contact lenses were first produced in 1961 by Czech chemical engineer Otto Wichterle using polyhydroxyethylmethacrylate (pHEMA), a material that achieved long-term commercial application. Lenses made of polyacrylamide were introduced in 1971.
Types
The FDA classifies soft contact lenses into four groups for the US market. They are also subcategorized into 1st generation, 2nd generation, and 3rd generation lens materials. 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.
The FDA has been considering updating soft contact lens group types and related guidance literature.
Contact lens polymers
The materials that are classified in the 5 FDA groups include the ones listed in the next 5 sections:
| FDA lens group | Adopted name | Transmissibility level (Dkx10-11) | Water content | Chemical composition |
|---|---|---|---|---|
| I non-ionic low water content | galyfilcon A | 60 | 47% | – |
| lotrafilcon A | 140 | 24% | DMA, siloxane, TRIS | |
| lotrafilcon B | 110 | 33% | ||
| polymacon | 7.5 | 36% | HEMA | |
| tetrafilcon | 9.0 | 43.5% | HEMA, MMA, NVP | |
| II non-ionic high water content | alphafilcon A | 22.9 | 66% | HEMA, NVP |
| hilafilcon A | 26.9 | 70% | ||
| omafilcon A | 19.6 | 62% | HEMA, PC | |
| III ionic low water content | balafilcon A | 99 | 36% | NCVE, NVP, PBVC, TPVC |
| bufilcon A | 16.0 | 45% | DA, HEMA, MAA | |
| IV ionic high water content | etafilcon A | 17.0 | 58% | HEMA, MAA |
| ocufilcon D | 19.7 | 55% | ||
| vifilcon A | 16.0 | 55% | HEMA, MAA, PVP | |
| DA– diacetone acrylamide; DMA– N,N-dimethylacrylamide; HEMA– 2-Hydroxyethyl methacrylate; MAA– methacrylic acid; MMA– methyl methacrylate; NCVE– N-carboxl vinyl ester; NVP– N-vinyl pyrrolidone; PBVC– poly[dimethylsiloxyl] di[silybutanol] bis[vinyl carbamate]; PC– phosphorylcholine; TPVC– tris-(trimethylsiloxysilyl) propylvinyl carbamate; TRIS– tris-(hydroxylmethyl) aminomethane |
Hydrogel groups
Below is a list of most contact lens materials on the market, their water percentage, their oxygen permeability rating, and manufacturer brands. Note that the higher the oxygen transmissibility rating, the more oxygen gets to the eye.
Low-water nonionic
| Material | % Water | Oxygen Transmissibility (Dk/t) | Brands |
|---|---|---|---|
| Tefilcon | 38 | 8.9 | Cibasoft, Illusions, Torisoft, Softint, STD, LL Bifocal |
| Tetrafilcon A | 43 | 9 | Cooper Clear, Cooper Toric, Preference, Preference Toric, Vantage, Vantage Accents, Vantage Thin, Vantage Thin Accents |
| Crofilcon | 38 | 13 | CSI, CSI Toric |
| Helfilcon A/B | 45 | 12 | Continental Toric, Flexlens, Flexlens Toric, Flexlens Aphakic, Optima Toric, All X-Cel lenses |
| Mafilcon | 33 | 4 | Menicon |
| Polymacon | 38.6 | 8.5–24.3 | Allvue, Biomedics 38, Clearview, CustomEyes 38, EpconSOFT, EsstechPS, Esstech PSD, Esstech SV, Frequency 38, HD, HD-T, HDX, HDX-T, Horizon 38, Hydron Mini, Hydron Zero 4 SofBlue, Hydron Zero 6 SofBlue, Hydron Versa Scribe, Lifestyle MV2, Ideal Soft, Lifestyle Xtra, Lifestyle 4Vue, Lifestyle Toric Bifocal, LL38, Metrosoft ll Multifocal, Metrosoft Toric, Natural Touch, Occasions, Optima 38/SP, PS-45 Multifocal, Simulvue 38, Sof-form II, SofLens, SofLens38, SofLens Multi-Focal, Softics, SoftView, Unilens 38, Westhin Toric, EZvue Soft Contact Lens, Solotica |
| Hioxifilcon B | 49 | 15 | Alden HP Sphere, Alden HP Toric, Aquaease, Essential Soft Toric Multifocal, Flexlens, Quattro, Satureyes, Satureyes Toric and Multifocal, All X-Cel Lenses |
High-water nonionic
| Material | % Water | Oxygen Transmissibility (Dk/t) | Brands |
|---|---|---|---|
| Surfilcon A | 74 | 35 | |
| Lidofilcon A | 70 | 31 | ActiFresh 400, CV 70 |
| Lidofilcon B | 79 | 38 | |
| Netrafilcon A | 65 | 34.5 | |
| Hefilcon B | 45 | 10 | Optima Toric |
| Alphafilcon A | 66 | 32 | SofLens Toric for Astigmatism |
| Omafilcon A | 58–60 | 28–36.7 | Proclear 1-Day, Proclear EP, Proclear 1 day Multifocal, Proclear Multifocal Toric, Biomedics XC, Aveo |
| Omafilcon B | 62 | 21.3–52.3 | Proclear Sphere, Proclear toric, Proclear toric XR, Proclear multifocal, Proclear multifocal XR, Proclear multifocal toric |
| Vasurfilcon A | 74 | 39.1 | Precision UV |
| Hioxifilcon A | 59 | 28 | Alden HP Sphere, Alden HP Toric, ExtremeH₂O 59% Thin/Extra, Biocurve Gold Sphere and Toric, Aura ADM, Scout by Warby Parker, Hydro by Hubble, Miru 1 Day |
| Hioxifilcon D | 54 | 21 | Alden HP Sphere, Alden HP Toric, ExtremeH₂O 54%, Clarity H₂0, C-Vue Advanced Custom Toric |
| Nelfilcon A | 69 | 26 | Focus Dailies, Focus Dailies Toric/Progressive, Dailies AquaComfort Plus, FreshLook One-Day, Synergy, Triton |
| Hilafilcon A | 70 | 35 | |
| Hilafilcon B | 59 | 22 | SofLens 59, SofLens Daily Disposable, SofLens Daily Disposables for Astigmatism |
| Acofilcon A | 58 | 25.5 | Flexlens Tricurve Keratoconus |
| Nesofilcon A | 78 | 42 | Biotrue ONEday |
Low-water ionic
| Material | % Water | Oxygen Transmissibility (Dk/t) | Brands |
|---|---|---|---|
| Bufilcon A | 45 | 16 | Hydrocurve II 45, Soft Mate B |
| Deltafilcon A | 43 | 10 | Amsoft, Amsoft Thin, Comfort Flex, Custom Flex, Metrosoft, Soft Form Toric |
| Phemfilcon | 38 | 9 | Durasoft 2 |
High-water ionic
| Material | % Water | Oxygen Transmissibility (Dk/t) | Brands |
|---|---|---|---|
| Bufilcon A | 55 | 16 | Hydrocurve I, Hydrocurve 3 Toric, Softmate II |
| Perfilcon A | 71 | 34 | Permalens |
| Etafilcon A | 58 | 23.8–28 | Acuvue, Acuvue Bifocal, Acuvue 2, Acuvue 2 Colors, 1-Day Acuvue, 1-Day Acuvue Moist, 1-Day Acuvue Moist for Astigmatism, 1-Day Acuvue Moist Multifocal, 1-Day Acuvue Define, Colornova, Discon, Waldo, Natural Vue, Ocylens |
| Focofilcon A | 55 | 16 | Fre-Flex |
| Ocufilcon B | 52–53 | 16–24 | ClearSight 1-Day, Continental, Ocu-Flex 53 |
| Ocufilcon C | 55 | 16 | UCL55, UCL-Pediatric |
| Ocufilcon D | 55 | 17.8–28.1 | Biomedics 55 Premier asphere, Biomedics Toric, ClearSight 1-Day Toric, Horien 1-Day Disposable |
| Ocufilcon E | 65 | 22 | Ocuflex 65 |
| Ocufilcon F | 60 | 24.3 | Hydrogenics 60 UV |
| Phemfilcon A | 55 | 16 | Durasoft 3, Freshlook, Wildeyes |
| Methafilcon A | 55 | 17.9-37.6 | Biocurve Advanced Aspheric, Biocurve 1-Day, Biocurve Toric & Sphere, C-Vue 1-Day ASV, C-Vue 55, Edge III 55, Elite AC, Elite Daily, Elite AC Toric, Expressions Colors, Flexlens, Frequency 55 Sphere/Multifocal, HD2, HDX2, Horizon 55 Bi-Con, Hubble, Kontur, LL55, New Horizons, Revolution, Sauflon 55, Sof-form 55, Sunsoft Eclipse, Sunsoft Toric, Vertex Sphere, Vertex Toric |
| Methafilcon B | 55 | 14.5–31.3 | Frequency 55 Toric, Hydrasoft Sphere, Hydrasoft Sphere Thin, Hydrasoft Aphakic, Hydrasoft Aphakic Thin, Hydrasoft Toric, Hydrasoft Toric Thin |
| Vilfilcon A | 55 | 16 | Focus 1–2 Week Softcolors, Focus Monthly Softcolors, Focus Toric, Focus Progressives, Soft 55, Soft 55 EW |
Silicone hydrogel polymers
| Material | FDA Group | % Water | Oxygen Transmissibility (Dk/t) | Modulus (MPa) | Center Thickness (mm) | Brands |
|---|---|---|---|---|---|---|
| Lotrafilcon A | 1 | 24 | 175 | 1.5 | 0.08 | Air Optix Night & Day Aqua |
| Lotrafilcon B | 1 | 33 | 110–138 | 1.0 | 0.08 | O2Optix, Air Optix for Astigmatism, Air Optix Aqua, Air Optix Aqua Multifocal, Air Optix Colors |
| Galyfilcon A | 1 | 47 | 86 | 0.43 | 0.07 | Acuvue Advance with Hydraclear, Acuvue Advance for Astigmatism |
| Senofilcon A | 1 | 38 | 103–147 | 0.7 | 0.07 | Acuvue Oasys, Acuvue Oasys for Astigmatism, Acuvue Oasys for Presbyopia, Acuvue Oasys 1-Day, Acuvue Oasys 1-Day for Astigmatism, Acuvue Oasys with Transitions, Acuvue Oasys Max 1-Day, Acuvue Oasys Max 1-Day Multifocal |
| Senofilcon C | 41 | 129–147 | 0.77 | 0.07 | Acuvue Vita, Acuvue Vita for Astigmatism | |
| Sifilcon A | 1 | 32 | 82 | 0.08 | O2Optix Custom | |
| Comfilcon A | 1 | 48 | 116–160 | 0.75 | 0.08 | Biofinity, Biofinity toric, Biofinity XR, Biofinity XR toric, Biofinity Energys, Biofinity multifocal |
| Enfilcon A | 1 | 46 | 100 | 0.6 | 0.06 | Avaira, Avaira Toric |
| Balafilcon A | 3 | 36 | 91-130 | 1.1 | 0.09 | PureVision, PureVision Toric, PureVision Multi-Focal, PureVision2, PureVision2 for Astigmatism, PureVision2 Multi-Focal for Presbyopia |
| Delefilcon A | 33–99 (water gradient) | 156 | 0.7 | 0.09 | Dailies Total1, Dailies Total1 Multifocal, DailiesTotal1 for Astigmatism | |
| Narafilcon B | 1 | 48 | 55 | 1-Day Acuvue TruEye (old) | ||
| Narafilcon A | 46 | 118 | 0.66 | 0.085 | 1-Day Acuvue TruEye (new) | |
| Stenfilcon A | 54 | 80–100 | 0.4 | 0.08 | MyDay, MyDay toric, MyDay Multifocal, Kirkland Signature | |
| Somofilcon A | 56 | 57–86 | 0.5 | 0.07 | Clariti 1 day, Clariti 1 day toric, Clariti 1 day multifocal, Live daily disposable | |
| Fanfilcon A | 55 | 90–110 | 0.6 | 0.06 | Avaira Vitality, Avaira Vitality toric, 24H Toric | |
| Samfilcon A | 46 | 163 | 0.7 | 0.07 | Bausch & Lomb Ultra, Bausch & Lomb Ultra for Astigmatism, Bausch & Lomb Ultra for Presbyopia | |
| Elastofilcon | 0.2 | 340 | SilSoft Aphakic, SilSoft Super Plus | |||
| Kalifilcon A | 55 | 134 | 0.5 | 0.08 | Bausch & Lomb INFUSE | |
| Asmofilcon A | 40 | 161 | 0.9 | 0.08 | Miru 1month | |
| Verofilcon A | 51–80 (water gradient) | 100 | 0.6 | 0.09 | Alcon Precision1, Alcon Precision1 for Astigmatism | |
| Lehfilcon A | 55–99 (water gradient) | 154 | 0.6 | 0.08 | Total30 | |
| Olifilcon B | 47 | 120 | 0.6 | 0.08 | Kits Daily, Everclear Elite, Hubble SkyHy | |
| Olifilcon A | 47 | 150 | 0.6 | 0.08 | Everclear Plus, Everclear Air |
Production generations
There are three generations of silicone hydrogel contact lens materials:
| 1st Generation | 2nd Generation | 3rd Generation | |
|---|---|---|---|
| Material: | Lotrafilcon A, Balafilcon A | Senofilcon A, Galyfilcon A | Samfilcon A, Comfilcon A, Enfilcon A, Asmofilcon 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 |