KEY TAKEAWAYS

• Ocular surface homeostasis relies on coordinated tear film, epithelial, gland and blink function.
• Contact lenses alter pre- and post-lens tear dynamics, so successful wear depends on more than refractive correction.
• Modern materials balance oxygen delivery with wettability, moisture retention, mechanical compatibility and surface behaviour.
• Packaging solution forms the lens’s first biochemical and lubricating interface with the tear film.
• Clinical and in vitro evidence related to Bausch + Lomb INFUSE^® supports a systems-based discussion of material and packaging-solution attributes.

Ocular Surface Homeostasis and the Challenge of Contact Lens Wear

A healthy ocular surface depends on homeostasis: the coordinated function of the tear film, ocular surface tissues, glands and blink mechanism. Key contributors include:

• The tear film and blink mechanism
• Corneal and conjunctival epithelia
• Meibomian and lacrimal glands

Together, these structures support optical quality, lubrication, antimicrobial defence, epithelial health and comfort.¹ Disruption of this balance can contribute to tear film instability, hyperosmolarity, inflammation, epithelial stress, fluctuating vision and contact lens discomfort.^1,9

Because a contact lens sits within the tear film, lens wear can influence this homeostatic environment. By dividing the tear film into pre- and post-lens compartments, a lens can alter:

• Tear distribution and evaporation
• Lipid-layer behaviour
• Blink-related lubrication and tear film stability⁹

In everyday wear, these effects may be compounded by digital device use, reduced or incomplete blinking, low humidity and extended wear, which can contribute to end-of-day dryness, discomfort and potential discontinuation.^9,10 These considerations highlight why modern contact lens design must account for the interaction between the lens material, packaging solution, tear film and ocular surface, rather than focusing on any single property in isolation.

This Science in Focus article examines Bausch + Lomb INFUSE^® through that systems-based perspective, considering how the kalifilcon A lens material and packaging solution design may work together to support tear film stability, comfort and ocular surface balance.^1,3,10

From Material Performance to Ocular Surface Compatibility

With this systems-based perspective, material performance becomes a central component of ocular surface compatibility. Beyond correcting vision, the contact lens material must support oxygen delivery, tear spreading, hydration and mechanical interaction with the ocular surface.

Oxygen Permeability, Wettability, and Tear Film Stability

Silicone hydrogel materials increased oxygen permeability compared with traditional hydrogels, an important advance because the avascular cornea depends largely on atmospheric oxygen.^2,3,10

Oxygen transmission remains essential, but it does not fully predict comfort or wearing success. Other important attributes include:

• Wettability and tear spreading
• Hydration and moisture retention
• Surface stability^1,3,9,10

A wettable surface supports rapid, uniform tear spreading after each blink. Modern silicone hydrogels use internal wetting agents, surface modifications and hydrophilic networks to improve tear film compatibility while retaining high oxygen transmission.^1,3,9,10

Clinical evidence: In a randomized, double-masked, bilateral study, kalifilcon A retained 96.3% moisture after 16 hours and lost significantly less water than six comparator daily disposable silicone hydrogel lenses.⁵

Mechanical Compatibility, Surface Smoothness, and Friction

Each blink generates frictional and shear forces among the eyelids, lens, tear film and ocular tissues. Mechanical compatibility therefore depends on how the lens moves, flexes and interacts with the ocular surface.

Material stiffness (modulus) affects lid interaction and tissue response. Earlier, higher-modulus silicone hydrogels were associated with mechanical complications. Newer materials generally aim to reduce modulus while maintaining oxygen permeability.^2,12

Surface behaviour also matters:

• Smooth, wettable surfaces support tear spreading and may reduce blink-related friction.
• Higher friction, lipid deposition or protein adsorption may contribute to lens awareness, discomfort and ocular surface stress.^1,3,12-14

Integrating Material Attributes Within the Lens System

As the lens material used in Bausch + Lomb INFUSE^®, kalifilcon A illustrates this integrated approach by combining oxygen permeability, hydration, lower modulus, wettability and surface performance.⁵

No single metric determines comfort. Clinical performance reflects the combined effects of water content, oxygen transmissibility, modulus, wettability and friction within the tear film and ocular surface environment.^1-3,12-14

Beyond the Lens Polymer: Packaging Solutions as Part of the Lens System

Having considered kalifilcon A as the contact lens material used in Bausch + Lomb INFUSE^®, the next consideration is the packaging solution that accompanies the lens onto the eye. Packaging solution is part of the lens system, not simply a storage medium, and helps establish the initial biochemical and lubricating interface with the tear film.¹

Modern packaging formulations may include components intended to support:

• Hydration and lubrication
• Wettability and tear spreading
• Osmotic balance
• Protein stability and epithelial stress responses^1,6-8

The following sections summarize in vitro models used to examine how packaging solution components may relate to epithelial stress responses and tear protein preservation.

Osmotic Balance, Oxidative Stress, and Epithelial Support

Hyperosmolarity is associated with inflammation, epithelial stress and tear film instability. Osmoprotectants help cells maintain volume and function during osmotic challenge, while electrolytes support the ionic environment needed for normal corneal and tear film function.^1,4

Hyperosmolarity model: In an in vitro study, human corneal epithelial cells were exposed for 24 hours to daily disposable silicone hydrogel lens packaging solutions in a hyperosmolar milieu. After exposure, culture supernatants were analyzed for the inflammatory markers IL-6, IL-8 and MCP-1. The Bausch + Lomb INFUSE^® packaging solution containing erythritol and glycerin produced no significant increase in the markers, whereas several comparator solutions significantly increased one or more.⁶

Oxidative-stress model: Oxidative challenge provides a complementary way to assess epithelial stress. In a separate in vitro study, human corneal epithelial cells were exposed to hydrogen peroxide-induced oxidative stress after preincubation with the Bausch + Lomb INFUSE^® packaging formulation containing erythritol and glycerin. In this model, the solution demonstrated antioxidant and metabolic properties, supporting potential epithelial stress-related mechanisms.⁷

Some systems also include physiologically relevant electrolytes to more closely reflect the natural tear environment. However, the clinical contribution of individual packaging-solution components remains difficult to isolate.¹

Surface Conditioning, Lubrication, and Tear Protein Preservation

Surfactants in packaging solutions can lower surface tension, improve lens wettability and promote more uniform tear spreading, supporting lubrication at the lens-tear film interface.¹

The interface during wear is shaped by solution chemistry, surface wetting and tear proteins adsorbed to the lens.

Key tear proteins include:

• Lysozyme and lactoferrin
• Secretory IgA
• Other proteins involved in antimicrobial defense, lubrication and tear film stability^1,11

Because native lysozyme supports antimicrobial activity and lubrication, preserving its function is relevant to maintaining the biochemical environment of the lens–tear film interface.¹¹

Protein-stabilization model: In an in vitro model, Bausch + Lomb INFUSE^® packaging solution preserved 90.7% of lysozyme activity after sodium lauryl sulfate exposure; comparator daily disposable solutions preserved less than 5.0%.⁸

These findings provide mechanistic support for the role of packaging solution composition in the lens system, but they should be interpreted as in vitro evidence rather than direct clinical evidence of performance during wear.^6-8

A New Perspective on Maintaining Ocular Surface Homeostasis

Contact lens biocompatibility has progressed from a primary focus on oxygen transmission to a systems-based view encompassing:

• Tear film stability and hydration
• Mechanical compatibility and lubrication
• Epithelial stress responses
• Protein preservation^1,3,5

Bausch + Lomb INFUSE^® illustrates how material attributes and packaging-solution components can be considered together within one lens system. Relevant features include oxygen transmissibility, wettability, moisture retention, lower modulus, osmoprotectants, electrolytes, surfactants and protein-stabilizing components.^1-3,5-10

The clinically relevant question is how effectively the complete system supports comfort

References

1. Efron N, Brennan NA, Bright FV, Glasgow BJ, Jones L, Sullivan DA, Tomlinson A, Zhang J, et al. Contact lens care and ocular surface homeostasis. Contact Lens Anterior Eye. 2013;36(Suppl 1):S9-S13.
2. Tighe BJ. A decade of silicone hydrogel development: surface properties, mechanical properties, and ocular compatibility. Eye Contact Lens. 2013;39(1):4-12.
3. Stapleton F, Stretton S, Papas E, Skotnitsky C, Sweeney DF. Silicone hydrogel contact lenses and the ocular surface. Ocul Surf. 2006;4(1):24-43.
4. Jones L, Downie LE, Korb D, Benitez-del-Castillo JM, Dana R, Deng SX, et al. TFOS DEWS II Management and Therapy Report. Ocul Surf. 2017;15(3):575-628.
5. Schafer J, Steffen R, Reindel W. A clinical assessment of dehydration resistance for a novel silicone hydrogel lens and six silicone hydrogel daily disposable lenses. Presented at: American Academy of Optometry; 2020.
6. VanDerMeid K, Byrnes MG, McGrath D, Menzel T, Rah M, Reindel W, et al. Effects of a novel contact lens packaging solution on hyperosmolarity-induced IL-6, IL-8 and MCP-1 responses in a human corneal epithelial cell line. Presented at: British Contact Lens Association; 2021.
7. Lo T, Rah M, Kwon M, VanDerMeid K, Xie X, Lam MH. Analysis of antioxidant effects of a daily disposable contact lens packaging solution on human corneal epithelial cells. Presented at: British Contact Lens Association Asia; 2026.
8. Scheuer C, Barniak V, Rah M, Reindel W. Effect of daily disposable contact lens solutions in stabilizing the activity of a tear film protein. Presented at: British Contact Lens Association; 2021.
9. Craig JP, Willcox MDP, Argüeso P, Maïssa C, Stahl U, Tomlinson A, Wang J, Yokoi N, Stapleton F. The TFOS International Workshop on Contact Lens Discomfort: Report of the Contact Lens Interactions With the Tear Film Subcommittee. Invest Ophthalmol Vis Sci. 2013;54(11):TFOS123-TFOS156.
10. Walsh K, Jones LW, Morgan PB, Papas EB, Sulley A. Twenty-five years of silicone hydrogel soft contact lenses. Optom Vis Sci. 2025;102(6):361-374.
11. Omali NB, Subbaraman LN, Coles-Brennan C, Fadli Z, Jones LW. Biological and clinical implications of lysozyme deposition on soft contact lenses. Optom Vis Sci. 2015;92(7):750-757.
12. Lin MC, Yeh TN. Mechanical complications induced by silicone hydrogel contact lenses. Eye Contact Lens. 2013;39(1):115-124.
13. Vidal-Rohr M, Wolffsohn JS, Davies LN, Cerviño A. Effect of contact lens surface properties on comfort, tear stability and ocular physiology. Cont Lens Anterior Eye. 2018;41(1):117-121.
14. Lievens CW, Rayborn E. Tribology and the ocular surface. Clin Ophthalmol. 2022;16:973-980.

Author Disclosures

Authored and reviewed by Bausch + Lomb Global Medical and Scientific Affairs.

Bausch + Lomb INFUSE^® is a registered trademark of Bausch + Lomb Incorporated or its affiliates. Brand names can vary by market and product availability may differ by region. Please contact your local Bausch + Lomb representative for further information.