Silicone Hydrogel Materials Research Articles

International trends in prescribing extended wear soft contact lenses (2000–2023): An update

PurposeExtended wear has long been considered as the ultimate contact lens modality in terms of user convenience. The purpose of this work is to update earlier surveys by describing international trends in extended wear soft lens fitting between 2000 and 2023, inclusive. MethodAn annual contact lens prescribing survey was sent to eye care practitioners in up to 71 countries between 2000 and 2023, inclusive. Data relating to 282,142 soft contact lens fits undertaken in 20 countries returning reliable longitudinal data were analysed in respect of extended wear soft lens fitting. ResultsOver the duration of the work there was a very small decrease in the prescribing of extended wear soft lenses (p < 0.0001). More detailed inspection shows that prescribing of these lenses steadily increased from 5.8 % of all soft lens fits in 2000 to 11.6 % in 2007, then steadily decreased to 5.2 % in 2023. Of all soft contact lenses prescribed to males, 9.2 % were fitted for extended wear, compared with 6.7 % for females (p < 0.0001). The mean age of extended wear soft lens wearers at fitting was 34.7 ± 14.7 years, compared to 31.1. ± 14.10 years for daily soft lens wearers (p < 0.0001). Analysis of 1,948 recent extended wear soft lens fits (2019–2023, inclusive), in terms of material type, revealed that, on average, 86 % and 14 % of extended wear soft lenses were fitted using silicone hydrogel and hydrogel materials, respectively. ConclusionA modest increase in extended wear soft lens prescribing from 2000 to 2007 corresponded with the introduction of high oxygen transmissibility silicone hydrogel lenses. However, prescribing of this lens type declined thereafter, probably due to ongoing concerns over their increased rate of microbial keratitis, resulting in a prescribing rate in 2023 (5.2%) that was little different to that observed in 2000 (5.8%).

Physical Properties and Interaction With the Ocular Surface of Water-Gradient Contact Lenses.

Since the introduction of silicone hydrogel contact lenses, many silicone-hydrogel materials have been produced, including water-gradient contact lenses with a silicone hydrogel core and a thin hydrogel outer layer (e.g., delefilcon A, verofilcon A, and lehfilcon A). Their properties have been investigated in various studies assessing both the chemical-physical characteristics and the comfort, but the overall picture is not always consistent. In this study, water-gradient technology is reviewed by looking at basic physical properties both in vitro and in vivo and at the interaction with the human ocular surface. Surface and bulk dehydration, surface wetting and dewetting, shear stress, interaction with tear components and with other environmental compounds, and comfort are discussed.

Development of Functional Ophthalmic Materials Using Natural Materials and Gold Nanoparticles.

Ginsenoside, known as a natural substance, is a saponin component in ginseng and has various effects, such as antibacterial, antioxidant, and anti-inflammatory effects. In addition, gold nanoparticles can realize various optical and physical properties according to particle size and shape. For polymer polymerization, ginsenoside and gold nanoparticles were used as additives and copolymerized with a basic silicone hydrogel material. As gold nanoparticles, spherical and rod-shaped particles were used, and basic physical properties, such as water content, refractive index, and wettability of the prepared ophthalmic lenses, were measured. As a result of measuring the physical properties of the resulting polymer, it was found that the contact angle decreased by about 1.6% to 83.1% as the addition ratio of ginsenoside increased. In addition, as the addition ratio of metal nanoparticles increased, the refractive index was found to increase regardless of the shape of the nanoparticles. In addition, in the case of water content, the spherical shape gradually decreased according to the addition ratio, while the rod shape gradually increased according to the addition ratio. Therefore, it was found that the addition of ginsenoside, known as a saponin-based natural substance, has excellent wettability, and gold nanoparticles with different shapes have different properties. Thus, it is judged that the resulting copolymer can be utilized as a variety of highly functional ophthalmic polymer materials with high refractive index and high wettability.

Uptake and release of polyhexamethylene biguanide (PHMB) from hydrogel and silicone hydrogel contact lenses using a radiolabel methodology

PurposeThe purpose of this study was to evaluate the uptake and release of radiolabelled polyhexamethylene biguanide (PHMB) on reusable daily wear contact lenses (CLs) over 7 days. MethodsThree silicone hydrogel (SH) contact lens materials (lotrafilcon B, balafilcon A, senofilcon A) and two conventional hydrogel (CH) materials (etafilcon A, omafilcon A) were examined. In experiment 1 (1-day study), CLs were soaked in 2 mL of phosphate buffered solution (PBS) containing radiolabelled 14C PHMB (1 µg/mL) for 8 h. The release kinetics of 14C PHMB from the CLs was measured at t = 0.25, 0.5, 1, 2, 4, 8, and 24 h in fresh 2 mL PBS. In experiment 2 (7-day study), the CLs were soaked in the 14C PHMB (1 µg/mL) solution for 8 h followed by a 16-hour release in 2 mL PBS. The lens cycle was repeated daily for 7 days. After both experiments, the residual amount of PHMB remaining within the lenses was extracted to determine the total uptake of PHMB. ResultsIn experiment 1, the total uptake of PHMB for etafilcon A was significantly greater than senofilcon A (p = 0.01). There were no significant differences in total uptake of PHMB between other lens materials (p > 0.05). Etafilcon A released more PHMB compared to all other lens types over a 24-hr period (p < 0.001). In experiment 2, all CL materials continued to sorb more PHMB over time (p < 0.001). By day 7, the amount of PHMB sorbed by etafilcon A was significantly greater than senofilcon A (p = 0.02). After day 2, the CH materials released significantly more PHMB than the SH materials (p < 0.01). ConclusionThe CL materials continued to sorb PHMB with no signs of saturation after 7 days. All lens materials released a consistent amount of PHMB each day. Radioactive labelling provides a sensitive method of assessing the uptake and release of PHMB from CL materials.

Lens wear adaptation in neophytes wearing monthly replacement soft lenses

Purpose: Many eye care professionals (ECP’s) still advocate a gradual adaptation to lens wear in neophyte soft contact lens wearers, however this approach has limited supportive evidence. This study aimed to ascertain whether this adaptation period, given modern advancements in soft lens materials, was necessary for monthly disposable soft contact lenses, in both hydrogel and silicone hydrogel materials.

Clinical Performance Evaluation of a New Silicone Hydrogel Material

Purpose: This study evaluated the clinical performance of a new silicone hydrogel (SiHy) material, with a core lens material containing 55% water that gradually transitions to nearly 100% water at the outer surface.

Surface characterization of a silicone hydrogel contact lens having bioinspired 2-methacryloyloxyethyl phosphorylcholine polymer layer in hydrated state

Purpose: A new silicone hydrogel (SiHy) material was designed through surface modification of a cross-linkable bioinspired 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer for long-term ocular performance. The surface properties of this MPC polymer-modified lens were characterized under hydrated condition to reveal its unique surface structure and superior surface properties in lubricity and softness.

Evaluation of Pollen Adhesion to Verofilcon-A Soft Contact Lenses

Purpose: A new 1-day disposable soft contact lens (SCL), verofilcon-A, constructed of silicone hydrogel material, has recently become available in Japan. This SCL has a very smooth surface produced by using the SMARTSURFACE ® Technology, and it was expected that pollen particles and protein components would not adhere easily to its surface. We examined the degree of pollen adhesion to the surface of the verofilcon-A material SCL and compared the results with those of other 1-day disposable SCLs (1DSCL). Methods: To determine the number of pollen grains attached to the surface of different types of SCLs, 0.01 mg/ml of cedar pollen solution was dropped onto the surface of 13 types of 1DSCL. After 24 h, each 1DSCL was rinsed in a shaker and washed five times with saline (n = 10 for each 1DSCL type). The number of pollen particles adhered to the 1DSCL and the percentage of surface area occupied by pollen was determined. Results: The number of pollen particles on the 1DSCLs ranged from 0 to 185 in the 200 × 200 µm area. The number of particles was lowest in the delefilcon-A and verofilcon-A SCLs with 0 particles, and the number was higher in the other 11 1DSCLs. The number of pollen particles was negatively correlated with the water content (r = −0.48), oxygen permeability (Dk; r = −0.43), oxygen transmissibility (r = −0.42), and center thickness (r = −0.33) of the 1DSCLs. The pollen adhesion area ranged from 0.0% to 3.1% and was lowest in the delefilcon-A and verofilcon-A 1DSCLs. There were significant differences in the pollen adhesion area between colored 1DSCLs (2.73 ± 1.97%) and clear 1DSCLs (1.03 ± 1.01%, P&lt;0.001) and between hydroxyethyl methacrylate-based 1DSCLs (1.84 ± 1.45%) and silicone hydrogel-based 1DSCLs (0.05 ± 0.16%, P&lt;0.001). Conclusion: These findings indicate that the verofilcon-A 1DSCL processed with SMARTSURFACE™ Technology is an excellent option for SCL users with allergic conjunctivitis during the high pollen season.

Contact Lens Prescribing in Canada 2006

A questionnaire was used to identify current preferences for contact lens prescribing in Canada. Practitioners were asked to submit information on the first ten patients fit­ted with contact lenses immediately after receipt of the survey; 151 completed questionnaires were returned, detailing contact lens fits to 1,421 patients. The results indicated that of the patients fitted with contact lenses, the majority were prescribed soft lenses. The preferred modality was monthly planned replacement. Over 80% of the soft lens fits were with either silicone hydrogel or mid-water content materials, with an even split between the two material options. Of the rigid lens fits the ma­jority were for daily wear. The overnight wear of rigid lenses appears to be for the practice of orthokeratology. Practitioners are recommending multipurpose solutions for the majority of their soft lens patients (91%).

Preparation and Analysis of Functional Silicone Hydrogel Lenses Containing ZrO₂ and Antimony Tin Oxide Nanoparticles.

This study prepared silicone hydrogel ophthalmic lenses using 2-hydroxyethylmethacrylate (HEMA), synthesized silicone monomer (SID), dimethylarsinic acid (DMA), N-hydroxyethyl acrylamide (HEA), ethylene glycol dimethacrylate (a crosslinking agent, EGDMA), and azobisisobutyronitrile (an initiator, AIBN). Also, Zirconium oxide (ZrO₂), antimony tin oxide (ATO) nanoparticles were added to the silicone hydrogel material to analyze the characteristics of the nanoparticles. The mixture was heated at 130 °C for 2 hours to produce the ophthalmic contact lens by cast mould method. As a result, the manufactured silicone hydrogel lens was prepared having high oxygen permeability and tensile strength while satisfying the basic requirements of ophthalmic hydrogel lens materials. Also, the addition of ZrO₂ NPs increased tensile strength of the manufactured lens, and ATO NPs were found to improve wettability. Therefore, ZrO₂ and ATO nanoparticles can be used effectively as additives for functional ophthalmic silicone hydrogel lenses.

The Impact of Incubation Conditions on In Vitro Phosphatidylcholine Deposition on Contact Lens Materials.

Previous in vitro measurements of contact lenses commonly investigate the impact of nonpolar tear film lipids (i.e., sterols). Polar lipids, however, are equally important stabilizing components of the tear film. This research explores and presents further knowledge about various aspects of polar lipid uptake that may impact contact lens performance. This study evaluated the impact of incubation time, lipid concentration, and replenishment of an artificial tear solution (ATS) on the uptake of phosphatidylcholine (PC) onto conventional hydrogel (CH) and silicone hydrogel (SH) contact lens materials. Four SHs and two CH lens materials (n = 4) were soaked in a complex ATS containing radioactive 14C-PC as a probe molecule. Phosphatidylcholine uptake was monitored at various incubation time points (1, 3, 7, 14, and 28 days), with different ATS lipid concentrations (0.5×, 1×, 2×) and with and without regular replenishment of the ATS. Phosphatidylcholine was extracted from the lenses, processed, and counted by a β counter, and accumulated PC (μg/lens) was extrapolated from standard lipid calibration curves. All materials exhibited increasing PC deposition over time. Conventional hydrogel materials showed significantly lower PC uptake rates (P < .001) than any of the SH materials. Increasing lipid concentration in the ATS resulted in increased PC binding onto the contact lens materials (P < .001). Replenishing the ATS every other day, however, impacted the PC deposition differently, showing increased binding (P < .001) on CHs and reduced PC deposition for SH materials (P < .001). Length of incubation, lipid concentration in the ATS, and renewal of the incubation solution all influenced the amount of PC that sorbed onto various lens materials and therefore need to be considered when conducting future in vitro deposition studies.

BCLA CLEAR - Contact lens wettability, cleaning, disinfection and interactions with tears

Contact lens materials have undergone significant changes over the past 20 years, particularly with respect to the introduction of silicone hydrogel materials. Whilst this development addressed hypoxic issues, other important areas relating to contact lens success, notably comfort, require further research.Contact lens wettability remains a crucially important part of biocompatibility. Contact lenses can be made more wettable by incorporation of surfactants into blister packs, internal wetting agents, surface treatments or care solutions. However, there remains no clear association between contact lens wettability and comfort, making it challenging to determine the potential for these approaches to be of significant clinical benefit. Most contact lenses are used on a daily wear, reusable basis, which requires them to be disinfected when not worn. The ideal disinfecting solution would also improve comfort during wear. However, balancing these requirements with other factors, including biocompatibility, remains a challenge. Soft lens materials invariably take up and subsequently release certain components of disinfecting solutions onto the ocular surface. This may affect tear film stability and the normal ocular microbiome, and further research is needed in this area to determine whether this has any affect on comfort. Finally, contact lens materials sorb components of the tear film, and these interactions are complex and may change the biochemistry of the tear film, which in turn may affect their comfort.In conclusion, the interaction between lens materials, tear film and disinfection solution plays an important role in the biocompatibility of lenses. However, the exact role and whether this can be altered to improve biocompatibility and comfort during wear remains debatable. This report summarises the best available evidence to examine this complex relationship and the opportunities for practitioners to enhance in-eye comfort of contemporary lenses, along with providing suggestions for areas of study that may provide further information on this topic.

In vitro analysis of the interaction of tear film inflammatory markers with contemporary contact lens materials

PurposeSeveral clinical studies have suggested that reusable silicone hydrogel contact lens materials exhibit a two-times increased rate of corneal infiltrative events compared to reusable hydrogels. One potential factor contributing to this complication relates to the differential uptake of tear film-based pro-inflammatory cytokines. The purpose of this study was to use an in vitro assay to investigate whether four pro-inflammatory cytokines differed in their uptake onto six contemporary contact lens materials. MethodsConventional hydrogel (etafilcon A, omafilcon A) and silicone hydrogel (balafilcon A, comfilcon A, senofilcon A, somofilcon A) contact lens materials were soaked in solutions containing pro-inflammatory cytokines IL-1β, IL-6, IL-8 and TNF-α. Samples of the soaking solutions were collected over various time points and analyzed using the Meso Scale Discovery system, which served as a measurement of cytokine uptake onto the contact lens materials. ResultsBoth conventional hydrogels (etafilcon A, omafilcon A) and two of the four silicone hydrogels tested (balafilcon A, comfilcon A), exhibited some uptake of IL-1β, IL-8 or TNF-α (p < 0.05). Senofilcon A and somofilcon A did not exhibit uptake of any of these cytokines (p > 0.05). There was no uptake of IL-6 onto any of the contact lens materials investigated (p > 0.05). ConclusionThe contact lens materials tested did not exhibit any uptake of IL-6 and furthermore, did not exhibit more than 10 ± 3 % to 25 ± 12 % uptake of IL-1β, IL-8 or TNF-α. Numerous factors could contribute to the reported increase in corneal infiltrative events with reusable silicone hydrogel materials, however, based on these results, it appears that uptake of these four cytokines are unlikely to contribute to this finding.

The possibility of developing customized 3D-printed silicone hydrogel bolus for post-mastectomy radiotherapy

ABSTRACT 3D printing technology is widely used for fabricating bolus in post-mastectomy radiotherapy. 3D printed boluses are usually made from hard materials like Polylactic Acid, which can’t adhere to patients’ skin perfectly in clinical practice because of the patients’ uneven surfaces of chest walls and large radiotherapy area. In this work, the feasibility of 3D printing soft self-adhesion boluses using water tissue equivalent silicone hydrogel material in post-mastectomy radiotherapy was studied, and intensity modulated radiotherapy plans were designed to study the performance of the water tissue equivalent silicone hydrogel bolus by comparing to the results of using virtual boluses with the relative electron density of 1.09 in radiotherapy. The comparison demonstrated that water tissue equivalent silicone hydrogel boluses have better adhesive property than boluses made from hard materials. The average air gap volume between the water tissue equivalent silicone hydrogel bolus and patients’ skin is 9.5 cc. The average degree of adhesion and average maximuum air cavity dimension are 3.7% and 4.3 mm, respectively. The dose distribution of the virtual bolus and the water tissue equivalent silicone hydrogel bolus are roughly the same in Dose Volume Histogram.

Impact of morphology on O2 permeability in silicone hydrogel membranes: new insights into domain percolation from experiments and simulations

The transport of oxygen through silicone-hydrogel (SiHy) materials is of great interest in bio-materials' applications. In this study O2 permeability of hydrogels made from UV-cured polyacrylamide containing different siloxane co-monomers were analyzed through the traditional coulometric flux method, as well as by 1H NMR T1 relaxometry. It was shown by coulometric flux methods that the crosslinked polyacrylamide with short, linear siloxane side chains (polydimethylsiloxane (PDMS)) has higher O2 permeability as well as O2 solubility, as calculated from the composite diffusivity, than that with branched siloxane (tris-(trimethylsiloxysilyl-) (TRIS)). On the other hand, based on direct measurement from NMR T1 analyses, a slightly higher O2 solubility was observed for the samples with branched siloxane as expected from its larger free volume. In order to understand the reason behind this discrepancy, a series of morphological studies using 29Si and 1H NMR T2 relaxometry, as well as small-angle X-ray scattering (SAXS) were undertaken. These results are discussed in the context of molecular dynamic simulations undertaken on the same systems which together strongly suggest that morphology plays a critical role in O2 permeability. It is proposed that samples made from the linear silicone, PDMS, has a more pronounced siloxane phase separation than its bulky counterpart, TRIS. Significantly percolating hydrophobic silicone domains with twice the siloxane content are found for the PDMS sample with reduced tortuosity of the hydrophilic domain's percolating path. The mobility in the linear siloxane was also much higher which can be attributed to the molecular structure and to fewer interfacial and topological constraints arising from the different domain structure. Hence, we propose a framework for O2 permeability in SiHys, emphasizing the importance of percolated hydrophobic domain in designing SiHy with optimized O2 permeability. The study demonstrates that while a simple permeability measurement can be used for materials' comparison, the use of multiple orthogonal techniques is critical for developing a more complete understanding of small molecule transport in heterogeneous materials.

1 day SiH lenses: A good choice for my patients?

Dr Kathy Dumbleton and Anna Sulley summarise the key points from a recent peer-reviewed paper summarising the evidence of the published literature that supports the benefits of both a 1 day modality and silicone hydrogel materials from patient needs to clinical performance, health outcomes and compliance, and highlights the advantages that can be provided to both new and existing contact lens wearers. (C76679, one distance learning point suitable for optometrists, contact lens opticians and dispensing opticians)

In-vitro dewetting properties of planned replacement and daily disposable silicone hydrogel contact lenses

AimTo compare the in-vitro videokeratoscopic surface dewetting properties of new-generation silicone hydrogel (SiH) planned replacement contact lenses (CL) with those of daily disposable CLs. MethodA chrome coated cornea model was used for the in-vitro evaluation of surface dewetting. Pre-lens and post-lens film layers were formed by instilling a normal preservative-free normal saline solution (PFNs) (0.9 %) before and after the placement of the CL on the model cornea. The tests were carried out on fanfilcon A, lotrafilcon B, samfilcon A, and senofilcon A lenses, as well as such daily disposable lenses as delefilcon, nesofilcon A and senofilcon one day. Using videokeratoscopic methods, images were obtained at 30-second intervals up to 180 s in the lens and control groups and were analyzed by the ImajeJ® program. ResultsThe mean measured area of the keratoscopic rings was largest in the fanfilcon group (67.56 mm2), followed by 61.53 mm2 in the lotrafilcon A group and 64.60 mm2 in the samfilcon group, while the smallest area was measured in the senofilcon A group, at 56.90 mm2. The area was measured as 64.33, 63.09 and 68.39 mm2 for the delefilcon, nesofilcon and Senofilcon one day CLs, respectively. The dewetting patterns and properties differed in the CL groups (p < 0.05), while no significant differences were found between the measured areas of the planned replacement and daily disposable CL groups (p > 0.05). DiscussionVideokeratoscopy using in-vitro cornea models has been identified as a reproducible and reliable method for the analysis of the surface dewetting of CLs. The dewetting characteristics of CL groups have been found to differ from each other, despite all being produced from SiH materials. The surface wetting coating has been shown to affect CL dewetting performance.

Uptake and Release of a Multipurpose Solution Biocide (MAP-D) From Hydrogel and Silicone Hydrogel Contact Lenses Using a Radiolabel Methodology.

The purpose of this study was to evaluate the uptake and release of radiolabelled myristamidopropyl dimethylamine (MAP-D) on reusable daily wear contact lenses (CLs) over 7 days. Three silicone hydrogel (SH) CL materials (lotrafilcon B, balafilcon A, senofilcon A) and two conventional hydrogel (CH) materials (etafilcon A, omafilcon A) were tested. A short-term (experiment 1, N=4) and a longer-term (experiment 2, N=3) study was conducted. In experiment 1, the CLs were incubated in 2 mL of phosphate buffered solution (PBS) containing 14C MAP-D (5 μg/mL) for 8 hrs. The release of 14C MAP-D was measured at t=0.25, 0.5, 1, 2, 4, 8, and 24 hr in PBS. In experiment 2, the CLs were incubated in the 14C MAP-D solution for 8 hrs followed by a 16-hr release in PBS. This cycle was repeated daily for 7 days. At the end of both experiments, lenses were extracted to determine the total uptake of MAP-D. The radioactivity was measured using a beta scintillation counter. In experiment 1, all three SH lenses sorbed similar amounts of MAP-D (P=0.99), all of which were higher than the two CH materials (P<0.01). However, the CH materials released a greater amount of MAP-D than the SH materials (P<0.01). In experiment 2, the uptake of MAP-D in SH materials increased over 7 days, whereas the amount of MAP-D remained constant in the CH materials (P=0.99). Similar to experiment 1, the CH lenses released more MAP-D than SH lenses after 7 days (P<0.01). The SH materials absorbed greater amounts of MAP-D compared to CH materials. However, the CH materials released the greatest amount of MAP-D. Radioactive labelling of MAP-D offers a highly sensitive method of assessing the uptake and release profiles of biocides to CL materials.

Preparation and Properties of Silicone Hydrogel Material Containing Silane Group with Cobalt Oxide Nanoparticles through Thermal Polymerization

This research is conducted to analyze the compatibility of used monomers and produce the high functional hydrogel ophthalmic polymer containing silane and nanoparticles. VTMS (vinyltrimethoxysilane), TAVS [Triacetoxy(vinyl)silane] and cobalt oxide nanoparticles are used as additives for the basic combination of SilM (silicone monomer), MMA (methyl methacrylate) and MA (methyl acrylate). Also, the materials are copolymerized with EGDMA (ethylene glycol dimethacrylate) as cross-linking agent, AIBN (thermal polymerization initiator) as the initiator. It is judged that the lenses of all combinations are optically excellent and thus have good compatibility. Measurement of the optical and physical characteristics of the manufactured hydrophilic ophthalmic polymer are different in each case. Especially for TAVS, the addition of cobalt oxide nanoparticles increases the oxygen permeability. These materials are considered to create synergy, so they can be used in functional hydrogel ophthalmic lenses.

Tuning corneal epithelial cell adhesive strength with varying crosslinker content in silicone hydrogel materials.

PurposeTo quantify the effect of silicone hydrogel crosslink density on the adhesion at corneal epithelial cells/silicone hydrogel contact lens interface.MethodsA custom-built rheometer, referred to as the live cell monolayer rheometer, was used to measure the adhesive strengths between corneal epithelial cell monolayers and silicone hydrogel lens surfaces. The resulting stress relaxations of senofilcon A–derived silicone hydrogel materials with varying crosslinking densities and delefilcon A were tested. Senofilcon A–like materials labeled L1, L2, L3, L4, and L5 contained crosslinker concentrations of 1.2, 1.35, 1.5, 1.65, and 1.8 wt%, respectively. The residual modulus measured from the live cell monolayer rheometer provided a direct indication of adhesive attachment.ResultsWithin the senofilcon-derived series, the adhesive strength shows a surprising minimum with respect to crosslink density. Specifically, L1 (1.20%) has the highest adhesive strength of 39.5 ± 11.2 Pa. The adhesive strength diminishes to a minimum of 11.2 ± 2.1 Pa for L3, whereafter it increases to 14.5 ± 2.5 Pa and 18.1 ± 5.1 Pa for L4 and L5, respectively. The delefilcon A lens exhibits a comparable adhesive strength of 27.8 ± 6.3 Pa to L1.ConclusionsThese results demonstrated that increasing the crosslink density has a nonmonotonic influence on the adherence of lenses to mucin-expressing corneal epithelial cells, which suggests a competition mechanism at the cell/lens interface.Translational RelevanceBecause the adhesiveness of contact lenses to ocular tissues may impact the comfort level for lens wearers and affect ease of removal, this study suggests that lens adhesion can be optimized through the control of crosslink density.