Friction Measurements on Contact Lenses in Their Operating Environment

Roba, Marcella; Duncan, etc.; Hill, G. A.; Spencer, Nicholas D.; Tosatti, Samuele

doi:10.1007/s11249-011-9856-9

Cited by 97 publications

(130 citation statements)

References 17 publications

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“…Although the experimental conditions (e.g. counterbody geometry, normal load, sliding velocity) vary from study to study, the values obtained are of the same order of magnitude of those previously published for similar hydrogels: Yanez et al [34] reported analogous values for pHEMA hydrogels containing PVP, and Roba et al [28] also found comparable values for various commercial contact lenses.…”

Section: Characterization Of the Hydrogelssupporting

confidence: 74%

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About the effect of eye blinking on drug release from pHEMA-based hydrogels: anin vitrostudy

Galante

Paradiso

Moutinho

et al. 2015

Journal of Biomaterials Science, Polymer Edition

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Abstract:The development of new ophthalmic drug delivery systems capable of increasing the residence time of drugs in the eye and improve its bioavailability relatively to eyedrops has been object of intense research in recent years. Several studies have shown that drug loaded therapeutic soft contact lenses (SCLs) constitute a promising approach, with several potential advantages as compared with collyria. The main objective of this work is to study the effect of repetitive load and friction cycles caused by the eye blinking, on the drug release from hydrogels used in SCLs which, as far as we know, was never investigated before. Two poly-2-hydroxyethylmethacrylate based hydrogels, pHEMA-T and pHEMA-UV, were used as model materials. Levofloxaxin was chosen as model drug. The hydrogels were fully characterized in what concerns structural and physicochemical properties. PHEMA-UV revealed some superficial porosity and a lower short range order than PHEMA-T. We observe that the load and friction cycles enhanced the drug release from pHEMA-UV hydrogels. The application of a simple mathematical model, which takes into account the drug dilution caused by the tear flow, showed that the enhancement of the drug release caused by blinking on this hydrogel may be relevant in in vivo conditions. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems CorporationConversely, the more sustained drug release from pHEMA-T is not affected by load and friction cycles. The conclusion is that, depending on the physicochemical and microstructural characteristics of the hydrogels, blinking is a factor that may affect the amount of drug delivered to the eye by SCLs and should thus be considered. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems CorporationAbout the effect of eye blinking on drug release from pHEMA based hydrogels:an in vitro study The development of new ophthalmic drug delivery systems capable of increasing the residence time of drugs in the eye and improve its bioavailability relatively to eyedrops has been object of intense research in recent years. Several studies have shown that drug loaded therapeutic soft contact lenses (SCLs) constitute a promising approach, with several potential advantages as compared with collyria. The main objective of this work is to study the effect of repetitive load and friction cycles caused by the eye blinking, on the drug release from hydrogels used in SCLs which, as far as we know, was never investigated before.Two poly-2-hydroxyethylmethacrylate based hydrogels, pHEMA-T and pHEMA-UV, were used as model materials. Levofloxaxin was chosen as model drug. The hydrogels were fully characterized in what concerns structural and physicochemical properties. PHEMA-UV revealed some superficial porosity and a lower short range order than PHEMA-T.We observe that the load and friction cycles enhanced the drug release from pHEMA-UV hydrogels. The application of a simple mathematical model, which takes into account the drug dilution caused by the tear flow, show...

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Section: Characterization Of the Hydrogelssupporting

confidence: 74%

“…PVP increases the hydrophilicity of the material and has self-lubricant properties essential to the comfort and good performance of the contact lenses [27,28]. One hydrogel was prepared using an anhydrous mixture.…”

mentioning

confidence: 99%

About the effect of eye blinking on drug release from pHEMA-based hydrogels: anin vitrostudy

Galante

Paradiso

Moutinho

et al. 2015

Journal of Biomaterials Science, Polymer Edition

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“…Although CLs are widespread, a significant fraction of people are unable to wear them due to discomfort and ocular irritation. These symptoms are generally associated with physiological problems, such as the dry eye syndrome, and/or to proteins/lipids adsorption and friction between the eyelid and the anterior surface of the lens [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

“…Roba et al [18] state that this may lead to misleading results and concluded about the relevance of mimicking the eye's physiological environment, not only in what concerns parameters like the normal load and velocity, but also the lubricant solution composition. They suggest the use of a lubricant based on the packaging solution, containing lysozyme and serum, but without lipids.…”

Section: Introductionmentioning

confidence: 99%

The effect of albumin and cholesterol on the biotribological behavior of hydrogels for contact lenses

et al. 2015

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“…Contact lens wearers in particular experience ocular discomfort and this is one of the primary reasons for ceasing lens wear 3 . When a contact lens is placed on the eye, the friction coefficient between the lens material and the ocular surface has been shown to change 4 . There is evidence to suggest that dryness symptoms could be related to this altered friction 2,5,6 .…”

Section: Introductionmentioning

confidence: 99%

Impression Cytology of the Lid Wiper Area

Müntz

Doorn

Subbaraman

et al. 2016

JoVE

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Few reports on the cellular anatomy of the lid wiper (LW) area of the inner eyelid exist and only one report makes use of cytological methods. The optimization of a method of collecting, staining and imaging cells from the LW region using impression cytology (IC) is described in this study. Cells are collected from the inner surface of the upper eyelid of human subjects using hydrophilic polytetrafluoroethylene (PTFE) membranes, and stained with cytological dyes to reveal the presence of goblet cells, mucins, cell nuclei and various degrees of pre-and parakeratinization. Immunocytochemical dyes show cell esterase activity and compromised cell membranes by the use of a confocal scanning laser microscope. Up to 100 microscopic digital images are captured for each sample and stitched into a high-resolution, large scale image of the entire IC span. We demonstrate a higher sensitivity of IC than reported before, appropriate for identifying cellular morphologies and metabolic activity in the LW area. To our knowledge, this is the first time this selection of fluorescent dyes was used to image LW IC membranes. This protocol will be effective in future studies to reveal undocumented details of the LW area, such as assessing cellular particularities of contact lens wearers or patients with dry eye or lid wiper epitheliopathy. Video LinkThe video component of this article can be found at

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Friction Measurements on Contact Lenses in Their Operating Environment

Cited by 97 publications

References 17 publications

About the effect of eye blinking on drug release from pHEMA-based hydrogels: anin vitrostudy

About the effect of eye blinking on drug release from pHEMA-based hydrogels: anin vitrostudy

The effect of albumin and cholesterol on the biotribological behavior of hydrogels for contact lenses

Impression Cytology of the Lid Wiper Area

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