Article

Soft Contact Lenses

Hydrogel and Silicone Hydrogel Lens General Considerations

July 1, 2010

Soft Contact Lenses

Hydrogel and Silicone Hydrogel Lens General Considerations

The FDA gives each contact lens material a generic name. In general, all hydrogel and silicone hydrogel lens generic names end in the suffix “filcon” and all nonhydrogel lenses end in “focon.”

Hydrogel lenses are categorized into four groupings for purposes of evaluating effects of accessory products upon the lens material. Lenses with less than 50 percent water content are considered to be “low water” and the others are “high water.” Less reactive surfaces are termed “nonionic” and more reactive materials are labeled “ionic.” Silicone hydrogel lenses are low water.

Disinfection of hydrogel and silicone hydrogel lenses can usually be done safely and effectively by approved chemical or hydrogen peroxide systems. However, some Group 4 ionic polymers may react negatively with potassium sorbate- or sorbic acid-preserved solutions.

In the term Dk, D stands for diffusion and k for solubility. The oxygen permeability of hydrogel lenses is almost entirely the result of solubility and for GP materials almost entirely the result of diffusion. In silicone hydrogel materials, oxygen permeability is a combination of solubility and diffusion, with the larger amount from diffusion. That is, the hydrogel component in the formulation provides solubility and the silicone component provides diffusion. Each generic material below is accompanied by a representative Dk number.

A clinically useful approximation is to consider Dk values for hydrogel lenses in three groups:

H₂0																	Dk
38±%																	9±
55±%																	18±
75±%																	36±

It is also important to remember that Dk/t (central transmissibility) and Dk/t (average overall transmissibility) are dependent upon contact lens thickness configuration and are more important than Dk with hydrogel lenses. With silicone hydrogel contact lenses, Dk/t and Dk/t are more similar than with hydrogel lenses.

This table should assist you in identifying specific lenses in each category as related to disinfection and Dk; and it will also help you determine an appropriate mix of lens types for your practice.

GROUP 1

Low Water (<50% H₂0)
Nonionic Hydrogel Polymers

tefilcon (38%) (Dk = 8.9)

Cibasoft
Illusions
Softint
STD
Torisoft
LL Bifocal

tetrafilcon A (43%) (Dk = 9)

Cooper Clear
Cooper Toric
Preference
Preference Toric
Vantage Thin Accents
Vantage
Vantage Accents
Vantage Thin

crofilcon (38%) (Dk = 13)

CSI
CSI Toric

helfilcon A&B (45%) (Dk = 12)

Continental Toric
Flexlens
Flexlens Toric
Flexlens Aphakic
Optima Toric

mafilcon (33%) (Dk = 4)

Menicon

polymacon (38%) (Dk = 9)

Allvue

Biomedics 38

Clearview

CustomEyes 38

EpconSOFT

EsstechPS

Esstech PSD

Esstech SV

Frequency 38

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

PS-45 Multifocal

Simulvue 38

Sof-form II

Soflens

Soflens 38

Soflens Multifocal

Softics

SoftView

Unilens 38

Westhin Toric

hioxifilcon B (49%) (Dk = 15)

Alden HP
Alden HP Toric
Aquaease
Essential Soft Toric Multifocal
Flexlens
Quattro
Satureyes
Satureyes Toric and Multifocal

Note: All X-Cel lenses are available in helfilcon A, hioxifilcon A, hioxifilcon B, and methafilcon A.

Silicone Hydrogel Polymers

lotrafilcon A (24%) (Dk = 140)

Air Optix Night & Day Aqua

lotrafilcon B (33%) (Dk = 110)

0₂0ptix
Air Optix for Astigmatism
Air Optix Aqua Multifocal
Air Optix Aqua

galyfilcon A (47%) (Dk = 60)

Acuvue Advance
Acuvue Advance for Astigmatism

narafilcon B (48%) (Dk = 55)

1-Day Acuvue TruEye

senofilcon A (38%) (Dk = 103)

Acuvue Oasys
Acuvue Oasys for Astigmatism
Acuvue Oasys for Presbyopia

sifilcon A (32%) (Dk = 82)

0₂0ptix Custom

comfilcon A (48%) (Dk = 128)

Biofinity
Biofinity Toric

enfilcon A (46%) (Dk = 100)

Avaira
Avaira Toric

GROUP 2

High Water (>50% H₂0)
Nonionic Hydrogel Polymers

lidofilcon A(70%)(Dk = 31)

• Acti Fresh 400
•CV 70

alfafilcon A (66%) (Dk = 32)

Soflens Toric

omafilcon A (59%) (Dk = 33)

Biomedics XC
Proclear 1-Day
Proclear EP
Proclear Multifocal
Proclear Multifocal Toric
Proclear Sphere
Proclear Toric

vasurfilcon A (74%) (Dk = 39.1)

Precision UV

hioxifilcon A (59%) (Dk = 28)

Extreme H₂0 59% Thin
Extreme H₂0 59% Extra
Biocurve Gold Sphere and Toric

hioxifilcon D (54%) (Dk = 21)

Clarity H₂0
C-Vue Advanced Custom Toric
Extreme H₂0 54%
Extreme H₂0 54% Toric

nelfilcon A (69%) (Dk = 26)

Dailies AquaComfort Plus
Focus Dailies
Focus Dailies Toric
Focus Dailies Progressive
FreshLook One-Day
Synergy
Triton

hilafilcon B (59%) (Dk = 22)

SofLens Daily Disposable

acofilconA(58%)Dk = (25.5)

Flexlens Tricurve Keratoconus

GROUP 3

Low Water (<50% H₂0)
Ionic Hydrogel Polymers

bufilcon A (45%)(Dk = 16)

Hydrocurve II 45
Soft Mate B

deltafilcon A (43%)(Dk = 10)

Amsoft
Amsoft Thin
Comfort Flex
Custom Flex
Metrosoft
Soft Form Toric

phemfilcon A (38%) (Dk = 9)

DuraSoft 2
DuraSoft 2 Optifit

Silicone Hydrogel Polymers

balafilcon A (36%) (Dk = 112)

PureVision
PureVision Multi-Focal
PureVision Toric

GROUP 4

High Water (>50% H₂0)
Ionic Hydrogel Polymers

bufilcon A (55%) (Dk = 16)

Hydrocurve I
Hydrocurve 3 Toric
Softmate II

perfilcon (71%) (Dk = 34)

Permalens
Permalens XL
Permalens Therapeutic
Permalens Aphakic

etafilcon A (58%) (Dk = 28)

Acuvue
1-Day Acuvue
1-Day Acuvue Moist
Acuvue 2
Acuvue 2 Colours
Acuvue Bifocal

focofilcon A (55%) (Dk = 16)

Fre-Flex

ocufilcon B (53%)(Dk = 16)

ClearSight 1 Day
Continental
Ocu-Flex 53

ocufilcon C(55%)(Dk = 16)

UCL55
UCL-Pediatric

ocufilcon D (55%) (Dk = 19.7)

Biomedics 55
Biomedics 55 Premier
Biomedics Toric
ClearSight 1 Day Toric

ocufilcon E (65%) (Dk = 22)

Ocuflex 65

ocufilcon F (60%) (Dk = 24.3)

Hydrogenics 60 UV

phemfilcon A (55%) (Dk = 16)

DuraSoft 3
DuraSoft 3 Optifit
Freshlook
Freshlook Toric
Freshlook Colorblends
Wildeyes

methafilcon A (55%) (Dk = 18)

Biocurve Advanced Aspheric
Biocurve 1-Day
Biocurve Toric & Sphere
C-Vue1 Day ASV
C-Vue 55
Edge III 55
Elite AC
Elite Daily
Elite AC Toric
Flexlens
Frequency 55 Sphere & Multifocal
HD2
HDX2
Horizon 55 Bi-Con
Kontur
LL55
New Horizons
Sauflon 55 UV
Sauflon 55 Asphere
Sof-form 55
Vertex Sphere
Vertex Toric

methafilcon B (55%) (Dk = 18)

Frequency 55 Toric
Hydrasoft Sphere
Hydrasoft Toric

vilfilcon A (55%)(Dk = 16)

Focus 1-2 Week Softcolors
Focus Monthly Softcolors
Focus Progressives
Soft 55
Soft 55 EW

Spherical Clear and Visibility Tint Disposable and/or Planned Replacement Hydrogels

Disposable and/or Planned Replacement Tinted Enhancer and Opaque Hydrogels

Toric Disposable and/or Planned Replacement Hydrogels

Multifocal Disposable and/or Planned Replacement Hydrogels

Daily Wear Spherical Clear and Visibility Tint Hydrogels

Extended Wear Spherical Clear and Visibility Tint Hydrogels

Therapeutic Spherical Clear and Visibility Tint Hydrogels

Aphakic Spherical Clear and Visibility Tint Hydrogels

Special Design Spherical Clear and Visibility Tint Hydrogels

Daily Wear Tinted Enhancer and Opaque Hydrogels

Customized Tinting

Adventures In Color Technology, Alden Optical, Crystal Reflections, Custom Color Contacts, Specialty Tint, and Ciba Vision Special Eyes Program provide custom tinting of soft contact lenses for prosthetic and other uses. For specific information, call them. Their telephone numbers and addresses are listed in the company directory at the end of this booklet.

Marietta Vision states that the Chromagen lens is available for certain color deficiencies. It has a 5mm to 7mm tinted optic zone and custom parameters. Call (866) 300-6257 for details.