Pre-contact lens and pre-corneal tear film kinetics

Comparative Analysis of the Osmoprotective Effects of Daily Disposable Contact Lens Packaging Solutions on Human Corneal Epithelial Cells

Purpose

Contact lens (CL) wear challenges the balance of the ocular surface environment by increasing water evaporation and tear osmolarity. Maintaining ocular surface homeostasis during CL wear remains a goal of lens manufacturers and an important consideration for eye care professionals. The purpose of this study was to measure the metabolic activity and inflammatory responses of a transformed human corneal epithelial cell (THCEpiC) line under hyperosmotic conditions in the presence of CL packaging solutions.

Methods

CL packaging solutions sampled from seven daily disposable silicone hydrogel CL blister packages were prepared at 25% and made hyperosmolar (400 mOsm/kg) with NaCl. THCEpiCs were incubated with each solution for 24 hr, after which cell culture supernatants were collected. THCEpiC metabolic activity was determined by an alamarBlue assay. Concentrations in cell culture supernatants of inflammatory cytokine (interleukin [IL]-6) and chemokine (IL-8), as well as monocyte chemoattractant protein-1 (MCP-1), were quantitated by specific enzyme-linked immunosorbent assays.

Results

THCEpiC metabolic activity under hyperosmolar conditions decreased in the presence of somofilcon A and senofilcon A solutions (p=0.04 and 0.004, respectively), but no other solution (all p≥0.09). Concentrations of IL-6 increased in the presence of delefilcon A, somofilcon A, narafilcon A, and senofilcon A solutions (all p≤0.001), but no other solution (all p≥0.08), while those of IL-8 increased in the presence of all solutions (all p≤0.03) but kalifilcon A (p>0.99), and those of MCP-1 increased in the presence of delefilcon A, verofilcon A, somofilcon A, and stenfilcon A solutions (all p<0.0001), but no other solution (all p>0.99).

Conclusion

CL packaging solutions differ in their capacity to inhibit epithelial inflammation. THCEpiC inflammatory response was less in the presence of a CL packaging solution containing osmoprotectants than in solutions lacking osmoprotectants under moderately hyperosmolar conditions in vitro. Clinical studies are warranted to further substantiate the benefit of osmoprotectants.

The role of poroelastic diffusion in the transient wetting behavior of hydrogels

Wetting and water absorption of hydrogels is often encountered in many applications. We seek to understand how wetting behavior can be affected by the time-dependent swelling of hydrogels. We measured the advancing contact angles of water droplets on hydrogels of varying thicknesses where thicker gels absorbed water more slowly. We also observed that, above a threshold advancing speed, water droplets would collapse into a lower contact angle state on the surface. We hypothesized that this collapse threshold speed is a result of competition between the poroelastic diffusion of water into the gel and the advance of the spreading droplet, the thickness of the surface, and the diffusion of water into the gel. Taking the ratio of the diffusion and advancing timescales results in a Peclet number with gel thickness as a characteristic length scale. Our results show that above a Peclet number of around 40, droplets will collapse on the surface across all gel thicknesses, confirming our hypothesis. This work provides simple insight to understand a complex time-dependent wetting phenomenon for a widely used hydrogel.

Impact of the physical properties of contact lens materials on the discomfort: role of the coefficient of friction

Contact Lens Discomfort (CLD) is the main cause in contact lens (CLs) discontinuation, referred in literature as drop-out phenomenon. Despite such evidence was reported in several clinical studies, a relationship between physico-chemical properties of CLs and CLD is not still totally understood. In this regard, the friction of CLs surfaces seems to be related to discomfort feeling events, probably due to an alteration of the lubricate function of the tear film after the CL placement inside the ocular environment. In the last years, many studies have been finalized to the friction measurements of CLs surface, finding conflicting data due to a lack in standardized protocol. The aim of this review is primarily to show evident relationships between CLs surface properties (i.e. wettability, tear evaporation, tear film quality, etc.) and the coefficient of friction (CoF), resulting therefore the most relevant physical quantity in the CLs characterization. In addition, we reported the most recent studies in CLs tribology, which highlight that the introduction of a standard protocol in CoF measurements is necessary to obtain reproducible results, considering the aim to evaluate in a more precise way the relationship between this material surface property and comfort in CLs users.

Short-term application of diquafosol ophthalmic solution benefits children with dry eye wearing orthokeratology lens

Purpose

This aim of this study was to evaluate the effect of 3% Diquafosol Ophthalmic Solution (DQS) on children with dry eye from wearing overnight orthokeratology (OrthoK) lenses.

Methods

Myopic children aged 8-18 years with dry eye syndrome were enrolled in this prospective observational study, and they were grouped according to their OrthoK treatment history for at least 1 year. All participants received DQS 4 times per day for 1 month. The following indicators were measured at baseline 1 month after treatment: the Dry Eye Questionnaire-5 (DEQ-5), non-invasive tear meniscus height (TMH), non-invasive tear film break-up time (first and average, NIBUT-F and NIBUT-A), meibomian gland score (MG score), conjunctival hyperemia redness score (R-scan), and blink pattern analysis.

Results

A total of 104 participants (189 eyes) including 40 OrthoK wearers (72 eyes) and 64 Orthok candidates (117 eyes) completed the study. Of all, after DQS treatment for 1 month, DEQ-5 scores reduced from 5.54 ± 3.25 to 3.85 ± 2.98 (t = -3.36, p = 0.00). TMH increased from 0.20 ± 0.05 mm to 0.21 ± 0.05 mm (t = 2.59, p = 0.01), NIBUT-F and NIBUT-A were prolonged from 6.67 ± 4.71 s to 10.32 ± 6.19 s and from 8.86 ± 5.25 s to 13.30 ± 6.03 s (all p = 0.00), respectively. R-scan decreased from 0.69 ± 0.28 to 0.50 ± 0.25 (t = -9.01, p = 0.00). Upper MG scores decreased from 1.04 ± 0.32 to 0.97 ± 0.36 (t = -2.14, p = 0.03). Lower MG scores, partial blink rate, partial blinks, and total blinks did not change significantly. Both break-up time (BUT) and R-scan improved significantly after DQS treatment for 1 month (all p = 0.00) in OrthoK candidates and OrthoK wearers. Among the OrthoK wearers, TMH and dry eye symptoms increased significantly (all p = 0.00) but did not increase in OrthoK candidates (p > 0.05). There were no adverse events related to DQS.

Conclusion

Diquafosol Ophthalmic Solution was effective for children wearing overnight orthokeratology in relieving dry eye symptoms and improving ocular surface parameters, which may help improve children's OrthoK wearing tolerance and compliance.

Evaluation of Celligent® Biomimetic Water Gradient Contact Lens Effects on Ocular Surface and Subjective Symptoms

This study aimed to evaluate the non-invasive and subjective symptoms associated with Lehfilcon A water gradient silicone hydrogel contact lenses with bacterial and lipid resistance technology. A prospective, longitudinal, single-centre, self-controlled study was conducted among silicone hydrogel contact lens wearers. Non-invasive analysis of the pre-lens tear film was performed using the Integrated Clinical Platform (ICP) Ocular Surface Analyzer (OSA), and the meibomian glands were evaluated with the Cobra® HD infrared meibographer. After 30 days of contact lens wear, the subjects were re-evaluated to determine the changes in conjunctival redness, subjective dry eye disease, tear meniscus height, lipid pattern, and non-invasive break-up time. Results showed that the lipid layer thickness decreased significantly from 2.05 ± 1.53 to 0.92 ± 1.09 Guillon patterns, and the tear meniscus height decreased from 0.21 ± 0.04 to 0.14 ± 0.03. The mean pre-lens non-invasive break-up time (NIBUT) significantly increased from 15.19 ± 9.54 to 25.31 ± 15.81 s. The standard Patient Evaluation of Eye Disease (SPEED) score also decreased from 7.39 ± 4.39 to 5.53 ± 4.83. The results suggest that Lehfilcon A significantly reduced lipid and aqueous tear film volume but improved break-up time and subjective dry eye symptoms.

Dynamic Aspects of Pre-Soft Contact Lens Tear Film and Their Relation to Dry Eye: Basic Science and Clinical Relevance

Soft contact lens (SCL) perturbs the intimate connection between the pre-lens tear film (PLTF) and the ocular surface in various ways, i.e., (i) decrease in tear meniscus radius and aqueous tear thickness, (ii) attenuation of tear film lipid layer spread, (iii) limited wettability of SCL surface, (iv) increased friction with eyelid wiper, etc. This often results in SCL-related dry eye (SCLRDE) manifested as PLTF instability and contact lens discomfort (CLD). In this review, the individual contributions of factors (i-iv) to PLTF breakup patterns (BUP) and CLD are considered via the tear film-oriented diagnosis framework adopted by the Asia Dry Eye Society from a clinical and basic science perspective. It is shown that SCLRDE (due to aqueous deficiency, increased evaporation, or decreased wettability) and BUP of PLTF classify within the same types as the ones observed for the precorneal tear film. The analysis of PLTF dynamics reveals that the inclusion of SCL enhances the manifestation of BUP associated with (i) decreased thickness of PLTF aqueous layer and (ii) limited SCL wettability as shown by the rapid expansion of BUP area. PLTF thinness and instability result in increased blink-related friction and lid wiper epitheliopathy as major contributor to CLD.

Effect of Contact Lens Solutions in Stabilizing the Activity of Tear Lysozyme

Purpose

Interactions between tear proteins and the interfaces of contact lenses can be complex and can influence contact lens wear success. Tear proteins, including lysozyme, function to maintain the balance of ocular surface homeostasis, as evidenced by the effects of its conformation relative to stabilizing the tear film and its potential impact on corneal epithelial cells. Contact lens manufacturers include components in lens care and blister package solutions to help stabilize the tear film and preserve homeostasis. This in vitro study was performed to evaluate the ability of daily disposable contact lens package solutions to stabilize lysozyme and preserve its native conformation under denaturing conditions.

Methods

Lysozyme was added to contact lens solutions sampled from kalifilcon A, etafilcon A, senofilcon A, narafilcon A, nelfilcon A, verofilcon A, delefilcon A, somofilcon A, and stenfilcon A blister packages, then mixed with the protein denaturant sodium lauryl sulfate. Lysozyme activity was evaluated by adding test solutions to a suspension of Micrococcus luteus. Native lysozyme lyses the Micrococcus luteus cell wall, which decreases suspension turbidity. Stabilization of lysozyme activity was determined by comparing suspension turbidity before and after exposure to test solutions.

Results

Lysozyme stabilization was 90.7% for kalifilcon A solution, a statistically significant improvement (p < 0.05) compared to phosphate buffered saline (PBS, negative control). No significant improvement was observed with any other contact lens solution (all lysozyme stabilization < 5.00%).

Conclusion

The representative tear protein lysozyme was significantly more stable in the novel kalifilcon A contact lens solution containing multiple moisturizers and osmoprotectants than in PBS or other daily disposable contact lens solutions. The lysozyme activity assay provides mechanistic evidence that the kalifilcon A contact lens solution can stabilize proteins under conditions that typically denature proteins, which may contribute to maintaining ocular surface homeostasis.

Comparison of the Pre-Lens Tear Film Stability and Visual Performance of a Novel and Two Other Daily Disposable Contact Lenses in Healthcare Professionals Wearing Facial Masks for Prolonged Time

OBJECTIVE

To compare a novel daily disposable contact lens (DDCL) verofilcon A with other DDCL materials in terms of pre-lens tear film (PLTF) stabilization and visual performance for prolonged use in healthcare professionals with the use of masks.

METHODS

Subjects aged 20-40 years old were prospectively randomized into three study groups. Group 1: verofilcon A, group 2: nesofilcon A and group 3: senofilcon A. The subjects were evaluated at baseline with best corrected visual acuity (BCVA), non-invasive tear break up time (NIBUT) of pre-lens tear film, and high order aberrations (HoAs). After 28 days of CL use, NIBUT at 1, 4, 8, and 12 h, HoAs, contrast sensitivity (CS) with CVS100-E and contact lens dry eye questionnaire-8 (CLDEQ-8) were evaluated.

RESULTS

Between August and September 2021, 147 eyes of 77 subjects were included in the three study groups. At day 28, the CS scores at 18 cycles per degree, spatial frequencies, and the mean NIBUT scores at 4, 8, and 12 h were higher in the verofilcon A group compared to the nesofilcon A and at 12 h were higher compared to the senofilcon A (p < 0.05). The mean HoAs and CLDEQ-8 test scores were higher in the nesofilcon A group (p < 0.001).

CONCLUSION

The results of this study suggest the superiority of the PLTF stabilization ability of verofilcon A in healthcare professionals with prolonged use of mask. The improved CS and NIBUT scores of this lens could be explained by a new and unique surface technology with greater than 80% water content.

Dry eye disease and tear film assessment through a novel non-invasive ocular surface analyzer: The OSA protocol

We describe the role of OSA as a new instrument in the study of dry eye, and we recommend a protocol for conducting the tests as well as describe the advantages and disadvantages compared with other instruments. A comparison with other ocular surface devices (Tearscope Plus, Keratograph 5M, anterior-segment ocular coherence tomography, Easy Tear View-Plus, LipiView, IDRA, and LacryDiag) were presented due to manual or automatic procedure and objective or subjective measurements. The purpose of this study was to describe the OSA as new non-invasive dry eye disease diagnostic device. The OSA is a device that can provide accurate, non-invasive and easy-to-use parameters to specifically interpret distinct functions of the tear film. This OSA protocol proposed a lesser to higher non-invasive ocular surface dry eye disease tear film diagnostic methodology. A complete and exhaustive OSA and OSA Plus examination protocol was presented within the subjective questionnaire (Dry Eye Questionnaire 5, DEQ5), limbal and bulbar redness classification (within the Efron grade Scale, interferometry lipid layer thickness (LLT) (according to Guillon pattern), tear meniscus height (manually or automatic), first and mean non-invasive break up time (objective and automatic) and meibomian gland (MG) dysfunction grade and percentage (objective and automatic). The OSA and OSA Plus devices are novel and relevant dry eye disease diagnostic tools; however, the automatization and objectivity of the measurements can be increased in future software or device updates. The new non-invasive devices supposed represent a renewal in the dry eye disease diagnosis and introduce a tendency to replace the classic invasive techniques that supposed less reliability and reproducibility.

Evaluation of Ocular Surface Characteristics in Dry Eye Disease With and Without Soft Contact Lens Wear: A Comparative Study

OBJECTIVES

To investigate ocular surface alterations and in vivo confocal microscopic characteristics of the cornea in dry eye disease (DED) with contact lens wear (CLW).

METHODS

Sixty participants were divided into three groups: DED with CLW (n=20), DED without CLW (n=20), and normal control (n=20). Ocular surface parameters were evaluated. Basal tears and in vivo confocal microscopy images of the cornea were collected. Multiplex bead analysis was used to assess interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, nerve growth factor (NGF), and substance P (SP) in tears. Nerve morphology and dendritic cell density in corneal subbasal nerve images were calculated.

RESULTS

The DED with CLW group showed significantly higher ocular surface staining scores (P=0.022) and higher levels of IL-1β, NGF, and SP in tears (P=0.014, P=0.004 and P=0.025) than the DED without CLW group. Corneal dendritic cell density in the DED with CLW group was significantly higher than that in the normal controls (P=0.001) and DED without CLW group (P=0.043). Tear cytokine levels of IL-1β, NGF, and SP were correlated with ocular surface parameters in the DED with CLW group. Moreover, the years of CLW were positively correlated with corneal dendritic cell density (r=0.527, P=0.017) and negatively correlated with corneal nerve density (r=-0.511, P=0.021).

CONCLUSIONS

Patients with DED with CLW showed greater epithelial damage, elevated inflammatory cytokines and neuromediators in tears, and higher corneal dendritic cell density than patients with DED without CLW. The immune and nervous systems may be involved in contact lens-related DED.

Orthokeratology Lens Wear for 2 Years in Children Did Not Alter Tear Film Lipid Thickness by Non-Invasive Interferometry

Purpose

Previous studies suggest that overnight orthokeratology (OOK) may be detrimental to tear function. We aimed to investigate the effect of OOK on lipid layer thickness (LLT), blink pattern, and meibomian gland and elucidate the relationship of these variables.

Methods

Thirty-seven participants who wore OOK lenses every night for at least 2 years and twenty-four healthy non-contact lens wearers (controls) were enrolled in this retrospective study. LipiView interferometry, blink pattern analysis, the ocular surface status, and morphology and function of the meibomian gland were determined.

Results

The OOK group and healthy controls had similar LLT, blink patterns, ocular surface status, and the function of the meibomian gland. OOK participants demonstrated higher meiboscore in the lower eyelids (p < 0.05) but not in the upper eyelids. Within the OOK group, LLT was significantly impacted by the partial blink rate (p < 0.05) and the total score of the upper meibomian gland (p = 0.10).

Conclusions

Wearing OOK for 2 or more years increased lower eyelid meibomian gland dropout but did not have a reduction of LLT.

Ability of non-invasive tear break-up time to determine tear instability in contact lens wearers

PURPOSE

To evaluate the performance of precorneal and prelens non-invasive tear break-up time (NIBUT) measurements to determine tear instability in contact lens (CL) wearers.

METHODS

In this study, 50 eyes of 25 CL wearers were evaluated. Precorneal first and average NIBUTs and fluorescein tear break-up time (FBUT) were measured before wearing CLs in the morning. Those with FBUT less than 10 s were considered to have tear instability. After wearing CL, first and average prelens NIBUTs were measured at the 30th minute. The receiver operating characteristic (ROC) curve was analyzed to evaluate the performance of NIBUT measurements in the diagnosis of tear instability.

RESULTS

The FBUT value had a significant correlation with first and average precorneal NIBUT values (p < 0.001, r = 0.653 and p < 0.001, r = 0.628, respectively). The FBUT value had no correlation with the prelens first and average NIBUT values (p = 0.542 and p = 0.263, respectively). To understand the relationship between the precorneal and prelens NIBUT values measured by the automated method, their correlation was evaluated. There was no significant correlation between the precorneal and prelens NIBUTs (for all; p > 0.05). The area under curve (AUC) in ROC curve for the first and average precorneal NIBUTs were 0.842 (p < 0.001) and 0.810 (p < 0.001), respectively. The AUC values for the first and average prelens NIBUTs at the 30th minute of CL wear were 0.586 and 0.619, respectively (p = 0.317 and p = 0.166, respectively).

CONCLUSIONS

Precorneal NIBUT measurements may be useful in diagnosing tear instability. Prelens NIBUT values are not yet capable of adequately defining the tear film dynamics in CL wearers.

The relationship of pre-corneal to pre-contact lens non-invasive tear breakup time

Purpose

To examine the relationship between pre-corneal and pre-contact lens tear film stability (TFS), and to determine whether pre-corneal TFS is a reliable predictor of subsequent pre-lens TFS after a contact lens is placed on the eye.

Methods

667 records met inclusion criteria and were extracted from a soft contact lens multi-study database. Multivariable linear mixed effects models were fit to examine the association between pre-corneal and pre-lens TFS, adjusting for potential confounders and accounting for repeated measures. Receiver Operating Characteristic (ROC) analysis was employed to assess the predictive performance of pre-corneal TFS for subsequent pre-lens TFS. TFS was quantified for this analysis as the non-invasive tear breakup time (NITBUT).

Results

Pre-corneal NITBUT was significantly related to the pre-lens NITBUT at both 10 min (p<0.001) and 2–6 hrs (p<0.001) post-lens insertion. However, the sensitivities of pre-corneal NITBUT for predicting symptom-associated thresholds of pre-lens NITBUT ranged from 50–65%, and specificities ranged from 57–72%, suggesting poor-to-moderate diagnostic performance.

Conclusions

Despite the association of pre-corneal and pre-lens TFS, the inherent lability and sensitivity to environmental exposures of the tear film introduce significant variability into NITBUT measurements. Using pre-corneal NITBUT to identify likely successful contact lens candidates prior to fitting is thus not sufficiently accurate to be relied upon in the clinical setting.

Profiling of non-polar lipids in tears of contact lens wearers during the day

PURPOSE

This study explored whether the non-polar lipids in the human tear fluid lipidome show diurnal variation with and without contact lens wear. It also addressed the relationship between changes in ocular comfort during the day with the level of non-polar lipids.

METHODS

Tear samples were collected in the morning and evening with and without contact lenses using fine glass capillary tubes and were analysed by chip-based nano-electrospray ionization tandem mass spectrometric techniques. Tear levels of cholesteryl esters (CE), wax esters (WE) and triacylglycerides (TAG) were quantified.

RESULTS

TAG 48:0, 52:0 and WE 26:0/16:0, and 27:0/17:0 increased from morning to evening. TAG 52:2, WE 21:0/16:0, 21:0/18:1 and 28:0/18:1 decreased during the day when no lenses were worn. CE 21:0 was the only non-polar lipid that increased from morning to evening in contact lens wear. WE 21:0/16:0 and 27:0/17:0 were lower in the morning in contact lens wear compared to no lens wear (p ≤ 0.05). The level of non-polar lipids did not correlate with ocular comfort at the end of the day.

CONCLUSION

Even though the level of some of non-polar lipid species changed from morning to evening the total level of major tear non-polar lipids remained unchanged during the day with and without contact lens wear. The effect of change in the quantity and structure of lipid species on tear stability and ocular comfort warrants more investigation.