9 GP materials and care solutions

What major properties are used to evaluate GP contact lens materials?

• Oxygen permeability (Dk)

• Specific gravity

• Wetting angle

• Hardness

• Flexure resistance and modulus

• Surface treatments or enhancements

What does Dk represent, and what do D and k mean?

Dk represents a material’s oxygen permeability.

• D = diffusion coefficient: how easily oxygen moves through the polymer

  • Silicone increases oxygen diffusion

• k = solubility coefficient: how much oxygen dissolves in the material

  • Fluorine increases oxygen solubility

How does oxygen pass through a GP lens material?

Oxygen:

1. Dissolves into the polymer material through solvation

2. Diffuses through the polymer membrane

3. Exits the material through permeation

Therefore, oxygen permeability depends on both oxygen diffusion (D) and solubility (k).

What is Dk/t, and why is Dk/t more clinically useful than Dk alone?

Dk/t = oxygen transmissibility, or the amount of oxygen transmitted through an actual lens.

• Dk describes the oxygen permeability of the material itself.

• t represents lens thickness.

• As lens thickness increases, Dk/t decreases.

• Dk/t is more clinically valuable because oxygen delivery depends on both the lens material and the thickness of the finished lens.

How is Dk reported using the ISO/Fatt method?

Dk is measured at 35°C and reported in:

× 10⁻¹¹ (cm³ O₂ × cm)/(cm² × sec × mmHg)

Dk describes the material, whereas Dk/t describes oxygen transmission through the actual lens.

How is GP lens specific gravity classified?

• Low: ≤ 1.10

  • Example: Paragon HDS 100 = 1.10

• Medium: 1.11–1.20

• High: > 1.20

  • Example: Acuity 100 = 1.270

How can specific gravity affect a GP lens fit, and how can this effect be minimized?

A lens with a higher specific gravity is more likely to position inferiorly, especially when the lens is thick.

This is particularly relevant for:

• High-plus lenses, which are thicker centrally

• Prism-ballasted lenses, which contain additional thickness

To reduce inferior positioning:

• Make the lens as thin as possible

• Select a material with a lower specific gravity

What does the wetting angle indicate about the wettability of a GP lens material?

The wetting angle reflects how readily liquid spreads across the lens surface:

• Small wetting angle: liquid spreads across the surface → hydrophilic and more wettable

• Large wetting angle: liquid beads up on the surface → hydrophobic and less wettable

High-yield relationship:
Lower wetting angle = better wettability.

How do hydrophilic and hydrophobic GP materials differ on the sessile-drop test?

In the sessile-drop method, a liquid drop is placed on top of the lens material:

• On a hydrophilic surface, the drop spreads out and forms a small advancing angle

• On a hydrophobic surface, the drop beads up and forms a large advancing angle

The advancing angle is measured as the liquid advances across the lens surface.

What is the difference between the advancing and receding wetting angles?

• Advancing angle: measured at the leading edge as liquid advances over a dry surface

• Receding angle: measured as liquid withdraws from an already wetted surface

What is Young’s modulus, and what does it indicate about a GP lens material?

Young’s modulus measures a material’s resistance to elastic deformation or bending.

• Higher modulus: stiffer material that resists flexure

• Lower modulus: more flexible material that bends more readily

What general relationship exists between Dk and modulus in GP lens materials?

As Dk increases, modulus generally decreases.

Therefore, very high-Dk GP materials, particularly those with Dk >125, tend to be more flexible and have less resistance to bending than lower-Dk materials.

Why is modulus clinically important when selecting a very high-Dk GP material?

A very high-Dk material may provide better oxygen permeability but can have a lower modulus, making the lens more likely to flex or deform.

Material selection should therefore balance:

• Adequate oxygen permeability

• Adequate stiffness and flexure resistance

• Lens design and thickness

What are some examples of very high Dk GP materials

Menicon Z, Infinite, and Acuity 200 as examples of materials combining very high Dk, over 150, with modulus values around approximately 1,200–1,350 MPa.

How are the Rockwell and Shore D hardness methods used to evaluate GP materials?

• Rockwell hardness

  • Used for GP buttons

  • Typical range: 100–120

  • Measures resistance to compression

• Shore D hardness

  • Used for finished lenses

  • Typical range: 75–85

  • Measures resistance to scratching

What are the major types of GP lens surface treatment or enhancement?

• Plasma treated

• Plasma coated

• Polyethylene glycol, such as Hydra-PEG

These treatments or enhancements are used to modify the GP lens surface, particularly to improve surface wettability.

What is the main purpose of plasma treatment for GP lens materials?

Plasma treatment modifies the surface of a GP lens material without changing the material’s bulk properties.

Plasma treatment:

• Removes surface impurities

• Alters the surface’s chemical structure

• Alters and smooths the surface’s physical structure

• Lowers the wetting/contact angle, improving wettability

How does plasma treatment improve the chemical and physical structure of a GP lens surface?

Plasma treatment can:

• Create surface chemical groups or structures such as amide groups (N–C=O), fluoride ions, and silicates

• Remove impurities from the lens surface

• Smooth the physical surface by reducing surface irregularities

These changes make the inherently poorly wetting plastic surface more hydrophilic.

What happens to the wetting angle as plasma power increases?

As plasma power increases, the contact angle decreases substantially, indicating improved wettability.

What is Hydra-PEG, and with which lens types can Hydra-PEG be used?

Hydra-PEG, made by Tangible Sciences, is a covalently bonded hydrophilic coating applied to a contact lens surface.

Hydra-PEG can be applied to:

• Soft lenses

• GP lenses

• Hybrid lenses

The coating is designed to increase surface lubricity and water retention while resisting protein and lipid deposits.

Which solutions are compatible with Hydra-PEG-coated lenses?

• Tangible Clean

• Boston Simplus

• Unique pH

• Clear Care

• Clear Care Plus

Which products should not be used with Hydra-PEG-coated lenses?

Do not use:

• Progent

• Boston Advance Cleaner

• Optimum CDS

• Boston Enzymatic Cleaner

These products are incompatible with the coating and may damage or degrade the Hydra-PEG surface.

What is PMMA, and why was PMMA historically important as a contact lens material?

PMMA (polymethyl methacrylate) was the first available plastic with good optical properties suitable for contact lenses.

What are the major advantages and disadvantages of PMMA as a contact lens material?

Advantages:

• Excellent optical clarity

• Durable

• Scratch resistant

• Maintains lens shape

• Resistant to deposits

Major disadvantage:

• No oxygen permeability

• Therefore, PMMA can produce significant hypoxic corneal complications

What corneal adverse effects can result from PMMA-induced hypoxia?

The absence of oxygen permeability can cause:

• Corneal edema

• Corneal exhaustion syndrome

• Corneal neovascularization

• Endothelial polymegethism

• Endothelial pleomorphism

These adverse effects stem from chronic or repeated inadequate oxygen delivery to the cornea.

What are corneal endothelial polymegethism and pleomorphism?

• Polymegethism: increased variation in endothelial cell size

• Pleomorphism: increased variation in endothelial cell shape, with loss of the normal uniform hexagonal pattern

Both can indicate endothelial stress associated with chronic contact lens-induced hypoxia.

Mnemonic:

• PolyMEGAthism = variable cell magnitude/size

• PleoMORPHism = variable cell morphology/shape

How do low-Dk and high-Dk GP lenses differ in their effects on corneal swelling?

• Low-Dk GP materials, such as PMMA, produce greater corneal swelling because little or no oxygen passes through the lens.

• High-Dk GP materials provide more oxygen and therefore produce substantially less corneal swelling.

Why was cellulose acetate butyrate important in the development of GP contact lenses?

Cellulose acetate butyrate (CAB) was the first rigid gas-permeable material.

• First lenses made: 1970

• Initial lenses were not FDA approved

• FDA inspection occurred in 1975

• FDA approval received in 1978, making CAB the first approved GP material

• Dominated the GP market until 1982

How did CAB compare with PMMA?

CAB offered two main changes compared with PMMA:

• Low but measurable oxygen permeability: Dk approximately 3.75–5.90

• Greater flexibility than PMMA

Although CAB transmitted more oxygen than PMMA, its Dk remained relatively low.

Why were silicone-acrylate GP materials developed, and who developed them?

Silicone acrylates were developed to eliminate or reduce the corneal edema and other hypoxic adverse effects associated with PMMA.

Development is credited to:

• Norman Gaylord, chemist

• Leonard Seidner, OD

• U.S. Patent 4,120,570

The first silicone-acrylate lenses appeared in 1979, including Polycon I and Menicon O2.

What were the oxygen permeability and wettability of the early Polycon I silicone-acrylate lens?

Polycon I:

• Dk: approximately 3.1–5.0

• Wetting angle: 67°

The added silicone allowed oxygen to diffuse through the material, but the relatively large wetting angle indicated limited surface wettability.

What was the major advantage of silicone-acrylate materials over CAB and PMMA?

Silicone-acrylate materials offered better oxygen permeability:

• Typical Dk: approximately 10-20

• Greater Dk than both CAB and PMMA

• Reduced the risk of hypoxic corneal effects compared with PMMA

What were the major disadvantages of silicone-acrylate GP materials?

Silicone made the material hydrophobic, resulting in:

• Poor surface wettability

• Lipid and protein deposition

• Rapid surface drying

• Ocular redness

• Inconsistent or fluctuating vision

Higher-Dk silicone-acrylate materials were also associated with:

• Crazing

• Warpage

• Deposits

• Brittleness

How did second-generation silicone-acrylate materials balance oxygen permeability and wettability?

Second-generation silicone acrylates had Dk values of approximately 20–60.

• Increasing silicone increased oxygen permeability

• However, more silicone made the material softer, more hydrophobic, and less wettable

• Methacrylic acid (MA) was added to improve wettability

The silicone-to-methacrylic-acid ratio had to be limited because excessive silicone produced a lens that was too soft and poorly wettable.

Why did adding methacrylic acid to silicone-acrylate materials increase protein deposition?

Methacrylic acid improved wettability but also increased the lens surface’s ionicity.

• The resulting negatively charged surface attracted positively charged tear proteins

• This increased protein deposition

What properties did fluorine add to fluoroalkyl methacrylate GP materials?

Fluoroalkyl methacrylates were similar to silicone acrylates but included fluorine.

Fluorine provided:

• Good oxygen solubility

• Non-stick properties similar to Teflon

• Improved resistance to surface deposits

How do silicone and fluorine contribute differently to modern fluoro-silicone acrylate GP materials?

• Silicone increases oxygen diffusion (D)

  • Increases Dk

  • Also makes the material softer and more hydrophobic

• Fluorine increases oxygen solubility (k)

  • Allows a high Dk with less silicone

  • Improves wettability and provides non-stick properties

Together, silicone and fluorine create a more favorable balance of oxygen permeability, wettability, and material properties.

Why are fluoro-silicone acrylates considered the modern, more optimal GP material combination?

Fluoro-silicone acrylates can achieve:

• High oxygen permeability

• Less dependence on hydrophobic silicone

• Better surface wettability

• Less deposit adherence

• A more favorable balance of oxygen transmission, stiffness, and surface performance

This combination helps overcome the major limitations of earlier silicone-acrylate materials.

Why can we get away with low Dk corneal GP lenses in daily wear?

A low-Dk corneal GP lens can be acceptable for daily wear because oxygen reaches the cornea by more than just diffusion through the lens:

1. The eye is open, so atmospheric oxygen is readily available through the tear film.

2. A corneal GP lens is small and covers only the central cornea, leaving the peripheral cornea directly exposed.

3. The lens moves with each blink, producing tear exchange beneath the lens and bringing fresh, oxygenated tears to the cornea.

4. Corneal GP lenses are generally relatively thin, so their actual oxygen transmissibility, Dk/t, may still be sufficient despite a lower material Dk.

5. The lens is removed before sleep, when the closed eyelid already substantially reduces oxygen availability. Low-Dk materials should therefore not be used for overnight wear.

Which high-Dk F-S/A materials are appropriate for daily-wear corneal GP lenses, particularly thicker designs?

Common high-Dk materials include:

• Acuity 58: Dk 58

• Boston EO: Dk 58

• Optimum Comfort: Dk 65

• Fluoroperm 92: Dk 64

Acceptable applications include daily-wear corneal lenses for:

• Hyperopia

• Toric or multifocal designs

• Irregular corneas

• Thicker lens designs

Higher Dk helps compensate for the reduction in Dk/t caused by increased lens thickness.

Which common hyper-Dk F-S/A materials can be used for daily wear, overnight wear, scleral lenses, orthokeratology, and thick lenses?

Common hyper-Dk materials include:

• Acuity 100: Dk 111

• Boston XO: Dk 100

• Boston XO2: Dk 141

• Optimum Extra: Dk 100

• Optimum Extreme: Dk 125

• HDS 100: Dk 101

These materials are acceptable for:

• Daily wear

• Overnight wear

• Scleral lenses

• Orthokeratology

• Thick lens designs

Why are hyper-Dk materials preferred for overnight wear, orthokeratology, scleral lenses, and thick GP lenses?

These applications reduce oxygen delivery to the cornea:

• Overnight wear/orthokeratology: the closed eyelid reduces available oxygen

• Scleral lenses: large diameter, increased lens thickness, a post-lens fluid reservoir, and minimal tear exchange reduce oxygen delivery

• Thick lenses: increased thickness lowers Dk/t

Therefore, a higher material Dk is needed to maintain adequate oxygen transmissibility.

What are the major ultra-Dk F-S/A materials and their Dk values?

• Acuity 200: Dk 211

• Acuity 181: Dk 181

  • Material: tisilfocon A

• Menicon Z: Dk 163

  • Material: tisilfocon A

• Optimum Infinite: Dk 180

  • Tisilfocon A with a modified surface for better wettability

• Optimum Breathe: Dk 250

  • Indicated for scleral lenses

What important material tradeoff should be considered when selecting an ultra-high-Dk GP material?

Ultra-high Dk does not automatically mean the material is best for every lens.

As Dk increases, the material may have:

• Lower modulus and greater flexure

• Greater softness or brittleness

• More difficult surface wettability

• Greater manufacturing or handling challenges

Which GP materials are FDA-approved for extended-wear applications, and what are their indications?

• Boston Equalens II (oprifocon A): Dk 85

  • Indicated for orthokeratology

• Menicon Z (tisilfocon A): Dk 163

  • Approved for up to 30 days of continuous wear

• Optimum Infinite (tisilfocon A): Dk 180

  • Indicated for orthokeratology

• HDS 100 (paflufocon A): Dk 101

  • Indicated for orthokeratology

High-yield point: A high Dk alone does not automatically authorize extended wear. The specific material and lens design must have FDA approval for the intended extended-wear indication.

Why do GP materials used for extended or overnight wear require a high Dk?

During sleep, the closed eyelid reduces atmospheric oxygen reaching the cornea. A high-Dk material helps maintain adequate Dk/t and reduces hypoxia-related complications such as:

• Corneal edema

• Epithelial and stromal changes

• Neovascularization

• Endothelial stress

This is especially important for orthokeratology because the lens is intentionally worn overnight.

What is Menicon Z composed of, and what features improve its clinical performance?

Menicon Z contains:

• Fluoro-methacrylate

• Siloxanyl styrene

• Cross-linking agents

• A UV absorber

The material is also plasma treated, which modifies the hydrophobic surface to improve wettability without changing the bulk properties.

What are the key historical and regulatory facts about Menicon Z?

• Introduced in 1987

• Received FDA 510(k) clearance in 1996

• Received FDA premarket approval in 2000

• Approved for up to 30 days of continuous wear

• Material name: tisilfocon A

• Dk: 163

What is notable about the hardness and surface treatment of Menicon Z?

Menicon Z has a Rockwell hardness of 60, making the material relatively soft compared with the typical GP-button range previously listed as 100-120.

Because the material’s high oxygen permeability is associated with a more hydrophobic and relatively softer composition, plasma treatment is used to improve surface wettability.

What are the major types of GP lens care systems, and what are common examples?

• Three-bottle system: discontinued Lobob system

• Two-bottle system: Boston Advance Cleaner + Boston Advance Conditioning Solution

• Multipurpose solutions: Boston Simplus and Unique pH

• Dual-indication systems for soft and GP lenses: Clear Care, Clear Care Plus, and Tangible Clean

What is the purpose of Boston Advance Cleaner, what ingredients perform each function, and what safety warning is essential?

Boston Advance Cleaner is the cleaning step of the Boston Advance two-bottle system.

• Surfactants: alkyl ether sulfate and ethoxylated alkyl phenol tri-quaternary cocoa-based phospholipid

  • Loosen and remove surface debris and deposits

• Microabrasive: silica gel

  • Mechanically assists deposit removal

• Visibility tint: titanium dioxide

  • Makes the cleaner easier to see during application and rinsing

Safety: Never place Boston Advance Cleaner directly into the eye. The lens must be thoroughly rinsed with multipurpose solution or saline after cleaning.

What are the two major functions of Boston Advance Conditioning Solution, and which ingredients provide them?

oston Advance Conditioning Solution provides disinfection and conditioning after the separate cleaning step.

Disinfection:

• Chlorhexidine 0.003%

• PHMB 0.0005%

• EDTA 0.05%

Conditioning:

• Polyethylene glycol (PEG): humectant that helps retain moisture

• Cellulose derivative polymer/cellulosic viscosifier: thickens the solution and increases lens-surface contact

• Polyvinyl alcohol (PVA): wetting agent that improves surface wettability

How are Boston Advance Cleaner and Conditioning Solution used together?

Boston Advance is a two-bottle system:

1. Rub the GP lens with the separate Cleaner to remove deposits.

2. Thoroughly rinse away the cleaner with saline or multipurpose solution.

3. Place the lens in the Conditioning Solution for disinfection, wetting, and storage.

How did the preservative systems of Boston GP solutions evolve over time?

• Boston Original: chlorhexidine 0.006% (60 ppm) plus EDTA 0.05%

• First-generation Boston Advance: PHMB 0.0015% (15 ppm)

  • Discontinued because the high PHMB concentration was too irritating

• Second-generation Boston Advance: chlorhexidine 0.003% (30 ppm) plus PHMB 0.0005% (5 ppm)

The newer Boston Advance formula uses less PHMB and combines it with chlorhexidine to maintain disinfection while reducing irritation.

What are the three main functions of Boston Simplus, and which ingredients provide each function?

Boston Simplus is a multipurpose GP solution that cleans, disinfects, and conditions.

• Cleaning

  • Poloxamine: surfactant

  • Hydroxyalkylphosphonate: daily protein remover

• Disinfection

  • Chlorhexidine 0.003%

  • PHMB 0.0005%

• Conditioning

  • Glucam: humectant that helps retain moisture

  • Hydroxypropyl methylcellulose: thickener that increases viscosity and lens-surface contact

How does Boston Simplus differ from the Boston Advance two-bottle system?

• Boston Simplus: one multipurpose solution that combines cleaning, disinfection, and conditioning

• Boston Advance: two separate products

  • Cleaner removes deposits and must be rinsed off

  • Conditioning Solution disinfects, wets, and stores the lens

Why can a GP-specific solution cause a toxic response when used with a soft contact lens?

Soft lenses absorb and retain preservatives, whereas GP lenses have little significant preservative uptake.

Because GP solutions can contain higher preservative concentrations, a soft lens may:

1. Absorb the preservative from the solution

2. Retain the preservative within the lens matrix

3. Release the preservative onto the ocular surface during wear

4. Produce a toxic or irritating ocular response

High-yield rule: Never assume a GP solution is safe for soft lenses unless the product specifically has a dual indication.

How does the PHMB concentration in Boston Simplus compare with Biotrue multipurpose solution, and why does the difference matter?

• Boston Simplus: PHMB 0.0005%

• Biotrue MPS: PHMB 0.00013%

• Boston Simplus contains approximately 3.84 times more PHMB

This higher concentration is generally tolerated by GP lenses because GP materials do not significantly absorb the preservative. A soft lens can absorb the higher PHMB concentration and potentially cause toxicity.

What are the major functions and ingredients of Unique pH?

Unique pH is a multipurpose GP solution that cleans, disinfects, and conditions.

• Cleaning

  • Poloxamine: surfactant

  • No specific protein-removing molecule

• Disinfection

  • Polyquaternium-1 0.0011%

  • EDTA 0.01%

• Conditioning

  • Propylene glycol and polyethylene glycol (PEG): humectants

  • Hydroxypropyl guar: thickener

How should GP lenses be cleaned and disinfected with Unique pH?

• Place 2 to 4 drops of Unique pH on each side of the lens.

• Rub each side of the lens.

• Thoroughly rinse both sides.

• Store the lenses in fresh Unique pH for at least 4 hours.

• Discard the bottle within 90 days after opening.

How do the recommended cleaning instructions differ between Boston Simplus and Unique pH?

• Boston Simplus

  1. Fill the case with fresh solution.

  2. Soak the lenses overnight to loosen debris.

  3. Remove the lenses and rub both sides for 20 seconds.

  4. Rinse with Boston Simplus.

  5. Discard the bottle within 90 days after opening.

• Unique pH

  1. Apply 2-4 drops to each lens surface.

  2. Rub and thoroughly rinse each side.

  3. Soak in fresh solution for at least 4 hours.

  4. Discard the bottle within 90 days after opening.

Quick distinction:
Simplus = soak first, then rub for 20 seconds; Unique pH = rub and rinse first, then soak for 4 hours.

How effective are current GP solutions at cleaning and disinfecting lenses?

Current GP solutions generally provide:

• Excellent disinfection

• Good deposit removal

Approximate cleaning efficacy:

• Boston Simplus: ~95% of deposits removed

• Optimum: ~95%

• Boston Advance: ~91%

• Unique pH: ~83%

How do common GP solutions compare in antimicrobial efficacy?

Boston Simplus, Unique pH, and Boston Advance produce strong microbial reduction against the tested organisms, including:

• Staphylococcus

• Pseudomonas

• Serratia

• Fusarium

• Candida

What are the major functions and active ingredients of Clear Care Plus?

Clear Care Plus is a hydrogen-peroxide system that cleans, disinfects, and conditions soft and GP lenses.

• Cleaning: Pluronic 17R4 surfactant

• Disinfection: 3% hydrogen peroxide

• Conditioning: polyoxyethylene-polyoxybutylene, or EO-BO 21

  • Also called HydraGlyde

  • Acts as a humectant to improve moisture retention

How should Clear Care Plus be used safely?

1. Remove each lens and rinse the lens with Clear Care Plus for 5 seconds.

2. Place each lens in the appropriate basket of the special case.

3. Fill the case with solution to the indicated line.

4. Close the case and soak the lenses for at least 6 hours.

5. After complete neutralization, remove the lenses and apply them to the eyes.

The hydrogen peroxide must be reduced to less than 100 ppm before lens application.

Why must Clear Care Plus be used only with its special lens case and allowed to neutralize completely?

The special case contains a neutralizing catalyst that converts irritating 3% hydrogen peroxide into safer end products.

Placing unneutralized peroxide directly in the eye can cause significant burning and ocular-surface injury. Therefore:

• Never apply Clear Care Plus directly to the eye

• Never rinse a lens and insert the lens immediately

• Never use a standard flat lens case

• Always complete the minimum 6-hour neutralization cycle

How effective are hydrogen peroxide systems at removing lipid and protein deposits?

Hydrogen peroxide systems provide similar lipid removal to common multipurpose solutions.

For protein removal:

• All tested systems removed very little protein from senofilcon A

• Clear Care removed less protein from etafilcon A than Biotrue, but approximately the same amount as PureMoist

• Deposit removal varies with the lens material, not just the care solution

How effective is hydrogen peroxide at disinfecting GP lenses?

Hydrogen peroxide achieves strong disinfection against:

• Staphylococcus aureus

• Pseudomonas aeruginosa

• Serratia marcescens

• Candida albicans

• Acanthamoeba trophozoites

The graph shows weaker efficacy against:

• Fusarium keratoplasticum

• Acanthamoeba cysts, which fall below the indicated disinfection criterion

High-yield point: Hydrogen peroxide is highly effective against many organisms, but Acanthamoeba cysts are especially resistant.

What is Tangible Clean, and with which contact-lens materials is Tangible Clean approved for use?

Tangible Clean is a multipurpose solution that:

• Cleans

• Rinses

• Disinfects

• Stores lenses

Tangible Clean is cleared for:

• Soft lenses: HEMA and silicone hydrogel

• GP lenses: silicone acrylate and fluoro-silicone acrylate

• Hydra-PEG-coated lenses

What ingredients allow Tangible Clean to clean, disinfect, and condition contact lenses?

• Poloxamer: surfactant that cleans the lens

• Polyhexanide 0.0001% and EDTA: disinfecting/preservative system

• The poloxamer surfactant also helps condition GP lens surfaces

High-yield association: Tangible Clean is a dual-indication multipurpose solution that is compatible with Hydra-PEG.

How should contact lenses be cleaned and disinfected with Tangible Clean?

• Apply 3 drops of Tangible Clean.

• Rub each side of the lens for 15–20 seconds.

• Rinse each side of the lens.

• Store the lenses in fresh solution for at least 6 hours.

What is Progent, and how does Progent remove deposits from GP lenses?

Progent is an intensive GP lens cleaner that removes protein and lipid deposits through a powerful oxidizing reaction.

• Progent A: sodium hypochlorite, an alkaline bleach with a pH of approximately 11–13

• Progent B: potassium bromide

• Mixing A and B produces an oxidizing solution that turns yellow

• The solution attacks amino-acid side chains, causing protein degradation

How should Progent be used?

1. Mix Progent A and B together.

2. Soak the GP lenses for 25–30 minutes.

3. Remove the lenses after the recommended time.

4. Use the third vial of saline to thoroughly rinse away the Progent mixture.

Progent may be used weekly if desired.

What organisms and deposits is Progent effective against?

Progent provides:

• Protein removal

• Lipid removal

• Antimicrobial activity against:

  • Acanthamoeba

  • Bacteria

  • Fungi

  • Viruses, including pox viruses, HIV, HSV, adenovirus, and SARS-CoV-2

What is the major compatibility warning for Progent?

Do not use Progent on Hydra-PEG-coated lenses.

The strong oxidizing system can damage or degrade the Hydra-PEG surface coating. Progent should be reserved for compatible, uncoated GP lenses and used according to the recommended exposure time.

What was Miraflow, and what was its primary clinical purpose?

Miraflow was an extra-strength daily cleaner used for cleaning and disinfection, particularly for removing lipid and mucin deposits.

Its major ingredients included:

• 20% isopropyl alcohol

• Pluronic F-127: copolymer

• 10% Miranol H2M: surfactant

Miraflow was formerly produced by Ciba Vision, now Alcon, but the original product was discontinued. Similar formulations may be available from smaller manufacturers.

When is Boston Laboratory Lens Cleaner used, and who should use it?

Boston Laboratory Lens Cleaner is intended only for laboratory and professional use.

• Used for heavily deposited GP lenses

• Available through Bausch + Lomb or Art Optical

• Not intended for routine patient use or regular lens care

Why should Boston Laboratory Lens Cleaner not be used regularly or for extended soaking?

Boston Laboratory Lens Cleaner is a strong cleaning formulation intended for intensive deposit removal.

• Regular use may damage the lens surface or material

• Extended soaking can damage the lens

• The cleaner should only be used briefly and according to professional laboratory instructions

How do Miraflow, Boston Laboratory Lens Cleaner, and Progent differ?

• Miraflow: formerly an extra-strength daily cleaner, especially useful for lipid and mucin deposits; original product discontinued

• Boston Laboratory Lens Cleaner: professional-only rescue cleaner for heavily deposited lenses; extended exposure can damage the lens

• Progent: periodic oxidizing treatment for proteins, lipids, and broad antimicrobial activity; may be used weekly on compatible GP lenses but not on Hydra-PEG-coated lenses