Comparing on eye dehydration and corneal staining of three daily disposable contact lenses in a low humidity environment

Schäfer, Jeffery; Steffen, Robert; Vaz, Tara; Reindel, William

doi:10.1016/j.clae.2012.08.037

Cited by 4 publications

(3 citation statements)

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“…The performance of NarA and SenA can be explained with the limited ability of the internal wetting agents (PVP based) to protect the CL surface as compared to surface coatings. It is interesting that in spite of the “smart chemistry” technology, the limited loss of bulk water (confirmed also in our measurements) in the course of air exposure 47 and the very low (3%) bulk percentage of silicon, the X-ray photoelectron spectroscopy showed that the surface content of Si of the desiccated StenA sample was as high as 10.2%. 46 Such behavior agrees with the hypothesis that in StenA, the hydrophobic silicone material phase separates on a small length scale and in the course of desiccation these Si enriched domains appear at the CL surface as hydrophobic nonwettable spots.…”

Section: Discussionsupporting

confidence: 79%

Relationships between the material properties of silicone hydrogels: Desiccation, wettability and lubricity

et al. 2020

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Silicone hydrogels (SiHy), represent composite matrices composed of hydrophobic gas permeable silicone (Si) rich core and a surface enriched with hydrophilic polymer moieties. Their utilization in contact lens design requires number of SiHy properties (hydration, wettability, lubricity) to be optimized for the challenging conditions at the ocular surface. Typical limitations in literature are that (i) these properties are studied in isolation, monitoring only one parameter but not the rest of them, and (ii) measurements are performed with hydrated samples immediately after removal from storage solutions. Here we study the simultaneous evolution of critical material properties (evaporative loss of water, water contact angle, coefficient of friction) of different SiHy subjected to continuous blink-like desiccation/rehydration cycling. SiHy with wetting agents incorporated in their core (narafilcon A, senofilcon A) were particularly susceptible to extended desiccation. Stenfilcon A, a material with only 3% bulk Si content maintained its performance for 4 h of cycling, and delefilcon A (80% surface water content) resisted extended 8 h of desiccation/rehydration runs. Strong correlation exists between the evolution of SiHy wettability and lubricity at ≥4 h of blink-like cycling. Understanding the interplay between SiHy properties bears insights for knowledge based design of novel ophthalmic materials.

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Section: Discussionsupporting

confidence: 79%

Relationships between the material properties of silicone hydrogels: Desiccation, wettability and lubricity

et al. 2020

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“…While the delefilcon A lens quickly loses its surface water to exhibit water behavior similar to that of other silicone hydrogels, the nesofilcon A lens maintains its water over the first 15 minutes of wear and dehydrates less than 2% over 16 hours of wear; 44 although the etafilcon A lens did not lose substantial surface water over the first 15 minutes of wear in this study, it loses in excess of 6% of its water content over an extended period of wear. 19 , 43 Dehydration of the delefilcon A lens surface previously reported suggests that the mechanism may be collapse of the hydrophilic surface moieties that attract water once in contact with the eye and the associated tear fluid under the shear of normal blinking. 49…”

Section: Discussionmentioning

confidence: 99%

“…In a previous study, the etafilcon A lens lost greater than 5% of initial water after 4 hours of wear in a controlled, 6% relative humidity environment, while the nesofilcon A lens lost less than 2%. 43 In a different study of the two lenses, water loss was measured over 16 hours of wear in uncontrolled, ambient humidity. 44 While the etafilcon A lens continued to lose water over 16 hours of wear (>6%), the nesofilcon A lens water loss was consistently below 2% over the course of the day ( Figure 1 ).…”

Section: Discussionmentioning

confidence: 99%

Evaluation of surface water characteristics of novel daily disposable contact lens materials, using refractive index shifts after wear

Schäfer¹,

Steffen²,

Reindel³

et al. 2015

OPTH

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PurposeContact lens wearers today spend much time using digital display devices. Contact lens manufacturers are challenged to develop products that account for longer periods of time where blink rate is reduced and tear-film evaporation rate is increased, affecting both visual acuity and comfort. Two manufacturers recently introduced novel daily disposable contact lenses with high surface water content. The objective of the present study was to compare surface water characteristics before and after initial wear of recently introduced nesofilcon A and delefilcon A high surface water lenses with those of etafilcon A lenses.Patients and methodsTwenty healthy subjects wore each of the three lens types studied in a randomly determined order for 15 minutes. After each wearing, lenses were removed and the surface refractive index (RI) of each lens was immediately measured.ResultsThe mean RI of the unworn delefilcon A lens was 1.34, consistent with water content in excess of 80%. After 15 minutes of wear, the surface RI shifted to 1.43, consistent with its reported 33% bulk water content. In contrast, the mean surface RI of the nesofilcon A lens was 1.38, both initially and after 15 minutes of wear, and that of the etafilcon A lens was 1.41 initially and 1.42 after 15 minutes of wear.ConclusionThe surface of the delefilcon A lens behaves like a high water hydrogel upon insertion but quickly dehydrates to behave like its low-water silicone-hydrogel bulk material with respect to surface water content during wear, while both nesofilcon A and etafilcon A lenses maintain their water content during initial wear. The nesofilcon A lens appears unique among high water lenses in maintaining high surface and bulk water content during wear. This is important because changes in surface RI due to dehydration are reported to lead to visual aberration affecting user experience.

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Comfort, Ocular Dryness, and Equilibrium Water Content Changes of Daily Disposable Contact Lenses

Pereira

Lira²

2018

Eye &Amp; Contact Lens: Science &Amp; Clinical Practice

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Comparing on eye dehydration and corneal staining of three daily disposable contact lenses in a low humidity environment

Cited by 4 publications

References 0 publications

Relationships between the material properties of silicone hydrogels: Desiccation, wettability and lubricity

Relationships between the material properties of silicone hydrogels: Desiccation, wettability and lubricity

Evaluation of surface water characteristics of novel daily disposable contact lens materials, using refractive index shifts after wear

Comfort, Ocular Dryness, and Equilibrium Water Content Changes of Daily Disposable Contact Lenses

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