Evaluation of daily disposable senofilcon A contact lenses in a symptomatic population.

PURPOSE: To evaluate the comfort performance of ACUVUE OASYS® 1-Day with HydraLuxe™ Technology among symptomatic contact lens wearers by using Contact Lens User Experience (CLUE) comfort scores and Contact Lens Dry Eye Questionnaire 8 (CLDEQ-8) discomfort and dryness scores. METHODS: Three clinical trials evaluated comfort and dryness when refitting symptomatic contact lens wearers to ACUVUE OASYS® 1-Day with HydraLuxe™ lenses. This analysis combined the CLUE comfort and CLDEQ-8 scores obtained at baseline and 2-week follow-up and compared average scores between visits. Subjects were grouped by habitual lens modality (daily disposable or daily wear reusable) and habitual lens material (silicone hydrogel or hydrogel). The analysis included data from 107 subjects. RESULTS: Significant increases in mean CLUE comfort scores between baseline and 2-week follow-up occurred in all subject groups across habitual lens modality and material, indicating an improvement in overall comfort. CLUE comfort score improved clinically (≥5-point increase) among 75.7% of subjects (81/107). Similarly, significant decrease in mean CLDEQ-8 scores between baseline and 2-week follow-up occurred in all subject groups, indicating a decrease in the prevalence of dryness and discomfort symptoms. CLDEQ-8 score improved clinically (≥3-point reduction) among 82.2% of subjects (88/107). A majority of subjects (57.0%) became asymptomatic (CLDEQ-8 score ≤ 11 points) after 2 weeks of bilateral wear. CONCLUSION: Refitting symptomatic contact lens patients to ACUVUE OASYS® 1-Day with HydraLuxe™ can improve overall comfort and reduce symptoms of dryness and discomfort, irrespective of the previous lens modality or habitual lens material.

Management of digital eye strain.

Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer workers and contact lens wearers.

Surface versus bulk activity of lysozyme deposited on hydrogel contact lens materials in vitro.

PURPOSE: To determine and compare the levels of surface versus bulk active lysozyme deposited on several commercially available hydrogel contact lens materials. METHODS: Hydrogel contact lens materials [polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon and etafilcon A with polyvinylpyrrolidone (PVP)] were incubated in an artificial tear solution for 16 h. Total activity was determined using a standard turbidity assay. The surface activity of the deposited lysozyme was determined using a modified turbidity assay. The amount of active lysozyme present within the bulk of the lens material was calculated by determining the difference between the total and surface active lysozyme. RESULTS: The etafilcon A materials showed the highest amount of total lysozyme activity (519 ±â€¯8 µg/lens, average of Moist and Define), followed by the ocufilcon material (200 ±â€¯5 µg/lens) and these two were significantly different from each other (p < 0.05). The amount of surface active lysozyme on etafilcon and ocufilcon lens materials was significantly higher than that found on all other lenses (p < 0.05). There was no active lysozyme quantified in the bulk of the nelfilcon material, as all of the active lysozyme was found on the surface (1.7 ±â€¯0.3 µg/lens). In contrast, no active lysozyme was quantified on the surface of polymacon, with all of the active lysozyme found in the bulk of the lens material (0.6 ±â€¯0.6 µg/lens). CONCLUSIONS: The surface and bulk activity of lysozyme deposited on contact lenses is material dependent. Lysozyme deposited on ionic, high water content lens materials such as etafilcon A show significantly higher surface and bulk activity than many other hydrogel lens materials.

The Effect of Denatured Lysozyme on Human Corneal Epithelial Cells.

Purpose: During contact lens wear, the amount of lysozyme deposited on contact lenses varies depending on the lens material. The binding of lysozyme to some contact lens materials may result in a conformational change that denatures the protein to an inactive form. This investigation evaluated the effect that denatured lysozyme has on human corneal epithelial cells (HCECs) by measuring cell viability and the release of inflammatory cytokines. Methods: HCECs were exposed to lysozyme that was denatured to various activity levels. After 24-hour exposure to the lysozyme (1.9 mg/mL) in growth media, the cells were evaluated for cell viability using confocal microscopy. The metabolic activity of the cells was determined using an alamarBlue assay. Cell supernatants were analyzed for inflammatory cytokines. Results: Using confocal microscopy, there was no detectable change in the viability of the HCECs after exposure to the denatured lysozyme. However, using alamarBlue, a decrease in the metabolic activity of the HCECs exposed to denatured lysozyme was detected. HCECs exposed to lysozyme that was 67%, 47%, and 22% active showed a reduction in metabolic activity when compared with native (100% active) lysozyme and the media controls (P < 0.05). Exposure to the denatured lysozyme also caused an increase in the release of inflammatory cytokines (P < 0.05) from the HCECs. Conclusions: The results of this study show that denatured lysozyme can have a detrimental effect on HCECs. Both a reduction in metabolic activity and an increase in the release of inflammatory cytokines occurred after HCEC exposure to denatured lysozyme.

In Vitro Compatibility of Contact Lenses With Corneal Epithelial Cells.

PURPOSE: To determine the interaction of contact lenses of different materials with corneal epithelial cells grown in tissue culture. METHODS: Two different corneal epithelial cell lines were grown to confluence in culture media. Two hydrogel contact lenses with and without polyvinylpyrrolidone (PVP) {1-DAY ACUVUE MOIST (1-Day ACUVUE [hydrogel lenses]) and a silicone hydrogel contact lens, AIR OPTIX NIGHT & DAY} were removed from their blister packs, washed in phosphate-buffered saline, and applied to the cells. After exposure for 24 hr at 37°C, lenses were removed, and the corneal cells and supernatants processed. Supernatants from the cell assays were used to quantify the amount of 17 different cytokines that were produced using a multiplex bead assay. Cells were stained to assess amount of cell death (apoptosis or necrosis) or stained to determine the level of mitochondrial activity. Stimulants of necrotic death (latex) or apoptotic death (sorbitol) were used as positive controls. RESULTS: Cells produced cytokines during normal growth. Exposure of cells to the hydrogel lenses resulted in only minimal changes to normal production of cytokines, but latex or sorbitol produced the most change. Exposure of the cells to all three lenses caused 4% to 23% reduction in mitochondrial activity, whereas exposure to the positive controls caused 71% to 98% reduction in mitochondrial activity. Exposure of the corneal epithelial cells to contact lenses produced minimal morphological changes, whereas exposure to latex or sorbitol produced significant changes to the human corneal epithelial cell line. CONCLUSIONS: Exposure of corneal epithelial cells to contact lenses had minimal impact on their physiology. There was no difference in epithelial cell responses to hydrogel with or without PVP compared with the silicone hydrogel contact lens.

In Vitro Effect of Lysozyme on Albumin Deposition to Hydrogel Contact Lens Materials.

SIGNIFICANCE: Albumin deposition on contact lenses could be detrimental to contact lens (CL) wear because this may increase the risk of bacterial binding and reduce comfort. Lysozyme deposition on selected lens materials would reduce albumin deposition on lenses. PURPOSE: This study aims to determine if lysozyme deposition on CLs could act as a barrier against subsequent albumin adsorption, using an in vitro model. METHODS: Six hydrogel CL materials (etafilcon A, polymacon, nelfilcon A, omafilcon A, ocufilcon B, and nesofilcon A) were evaluated. Four CLs of each type were soaked in lysozyme solution for 16 hours at 37°C. Lysozyme-coated lenses were then placed in vials with 1.5 mL of artificial tear solution containing I-labeled albumin for 16 hours at 37°C with shaking. Four uncoated lenses of each type were used as controls. Lenses soaked in radiolabeled albumin were rinsed in a phosphate-buffered saline solution, and radioactive counts were measured directly on lenses using a gamma counter. Albumin uptake on lenses was measured using a calibration curve by plotting radioactive counts versus protein concentration. RESULTS: Results are reported as mean ± SD. Lysozyme-coated etafilcon A lenses exhibited lower levels of deposited albumin than uncoated etafilcon A lenses (58 ± 12 vs. 84 ± 5 ng/lens; P < .05). There were no differences in albumin adsorption between control (uncoated) and lysozyme-coated polymacon (105 ± 10 vs. 110 ± 34 ng/lens), nelfilcon A (51 ± 7 vs. 42 ± 20 ng/lens), omafilcon A (90 ± 20 vs. 80 ± 38 ng/lens), ocufilcon B (87 ± 20 vs. 115 ± 50 ng/lens), and nesofilcon A (170 ± 29 vs. 161 ± 10 ng/lens) lens materials (P > .05). Uncoated nesofilcon A lenses deposited the highest amount of albumin when compared with other uncoated lenses (P < .05). CONCLUSIONS: This study demonstrates that lysozyme deposited onto etafilcon A resists the deposition of albumin, which may potentially be beneficial to CL wearers.

Selectivity and localization of lysozyme uptake in contemporary hydrogel contact lens materials.

The purpose of this study was to investigate the early and selective uptake of lysozyme and the location of deposited lysozyme on contemporary hydrogel contact lens (CL) materials after exposure to an artificial tear solution (ATS) for 16 h. Seven different hydrogel CL materials [polymacon, omafilcon A, nelfilcon A, nesofilcon A, ocufilcon B, etafilcon A (Acuvue Moist), and etafilcon A (Acuvue Define)] were incubated in an ATS for various times. Total protein deposition was determined using a modified Bradford technique. Lysozyme, lactoferrin, and albumin deposition on CLs were determined using 125I-radiolabeling method. A confocal laser scanning microscopy (CLSM) technique was utilized to map the location of lysozyme uptake in an asymmetric environment. All lens materials had significant amounts of lysozyme after 1 min of exposure to ATS. After 16 h of incubation, higher levels of total protein deposited on the two etafilcon A-based lenses (Moist and Define), followed by ocufilcon B and both were significantly higher than all other CLs tested (p = 0.0001). The two etafilcon A materials (Moist and Define) also deposited the highest amounts of lysozyme (514.8 ± 28.4 and 527.1 ± 14.7 µg/lens respectively) when compared to other test CLs (p = 0.0001). The CLSM technique revealed that the non-ionic CLs tended to have symmetric distribution of lysozyme throughout the lens materials, while the ionic CLs had an asymmetric distribution, with the highest concentration of lysozyme on and near the exposed surface. The quantity and nature of proteins deposited on CLs varies, depending upon the chemical composition of the material. Among the various lenses tested, etafilcon A deposited the highest amount of total protein, most of it represented by lysozyme, which was largely located near the surface of the lens.

Biological and Clinical Implications of Lysozyme Deposition on Soft Contact Lenses.

Within a few minutes of wear, contact lenses become rapidly coated with a variety of tear film components, including proteins, lipids, and mucins. Tears have a rich and complex composition, allowing a wide range of interactions and competitive processes, with the first event observed at the interface between a contact lens and tear fluid being protein adsorption. Protein adsorption on hydrogel contact lenses is a complex process involving a variety of factors relating to both the protein in question and the lens material. Among tear proteins, lysozyme is a major protein that has both antibacterial and anti-inflammatory functions. Contact lens materials that have high ionicity and high water content have an increased affinity to accumulate lysozyme during wear, when compared with other soft lens materials, notably silicone hydrogel lenses. This review provides an overview of tear film proteins, with a specific focus on lysozyme, and examines various factors that influence protein deposition on contact lenses. In addition, the impact of lysozyme deposition on various ocular physiological responses and bacterial adhesion to lenses and the interaction of lysozyme with other tear proteins are reviewed. This comprehensive review suggests that deposition of lysozyme on contact lens materials may provide a number of beneficial effects during contact lens wear.