Another angle on contact lens surface analysis

Darren Campbell, Sarah Carnell, Gareth Ross, Brian Tighe

Research output: Contribution to conferencePoster

Abstract

Purpose: Dynamic contact angle (DCA) methods have advantages over other contact angle methodologies, not least that they can provide more than single contact angle values. Here we illustrate the use of DCA analysis to provide “fingerprint” characterisation of contact lens surfaces, and the way that different materials change in the early stages of wear.
Method: The DCA method involves attaching to a microbalance weighted strips cut from a lens. The strips are then cyclically inserted into and removed from an aqueous solution. Conventionally, readings of force taken from linear portions of the resultant dipping curves are translated into advancing (CAa) and receding contact (CAr) angles. Additionally, analysis of the force versus immersion profile provides a “fingerprint” characterisation of the state of the lens surface.
Results: CAa and CAr values from DCA traces provide a useful means of differentiating gross differences in hydrophilicity and molecular mobility of surfaces under particular immersion and emersion conditions, such as dipping rate and dwell times. Typical values for etafilcon A (CAa:63.1; CAr:37) and balafilcon B (CAa:118.4; CAr:36.4) illustrate this. Surface modifications induced in lens manufacture are observed to produce not only changes in these value, which may be small, but also changes in the DCA “fingerprint” (slope, undulations, length of plateau). Interestingly, similar changes are induced in the first few hours of lens wear with some lens-patient combinations.
Conclusions: Although single parameter contact angles are useful for material characterisation, information of potential clinical interest can be obtained from more detailed analysis of DCA traces.
Original languageEnglish
Pages284
Publication statusPublished - 2010
EventBritish Contact Lens Association - Birmingham, United Kingdom
Duration: 27 May 201030 May 2010

Conference

ConferenceBritish Contact Lens Association
CountryUnited Kingdom
CityBirmingham
Period27/05/1030/05/10

Fingerprint

emersion
slope angle
aqueous solution
plateau
methodology
analysis
method
material
rate
change in value
parameter

Bibliographical note

Abstract published on Abstracts / Contact Lens & Anterior Eye 33 (2010), 284-285 DOI http://dx.doi.org/10.1016/j.clae.2010.07.002

Cite this

Campbell, D., Carnell, S., Ross, G., & Tighe, B. (2010). Another angle on contact lens surface analysis. 284. Poster session presented at British Contact Lens Association, Birmingham, United Kingdom.
Campbell, Darren ; Carnell, Sarah ; Ross, Gareth ; Tighe, Brian. / Another angle on contact lens surface analysis. Poster session presented at British Contact Lens Association, Birmingham, United Kingdom.
@conference{08ac96ad585a47bd93896eea2b2c98de,
title = "Another angle on contact lens surface analysis",
abstract = "Purpose: Dynamic contact angle (DCA) methods have advantages over other contact angle methodologies, not least that they can provide more than single contact angle values. Here we illustrate the use of DCA analysis to provide “fingerprint” characterisation of contact lens surfaces, and the way that different materials change in the early stages of wear.Method: The DCA method involves attaching to a microbalance weighted strips cut from a lens. The strips are then cyclically inserted into and removed from an aqueous solution. Conventionally, readings of force taken from linear portions of the resultant dipping curves are translated into advancing (CAa) and receding contact (CAr) angles. Additionally, analysis of the force versus immersion profile provides a “fingerprint” characterisation of the state of the lens surface.Results: CAa and CAr values from DCA traces provide a useful means of differentiating gross differences in hydrophilicity and molecular mobility of surfaces under particular immersion and emersion conditions, such as dipping rate and dwell times. Typical values for etafilcon A (CAa:63.1; CAr:37) and balafilcon B (CAa:118.4; CAr:36.4) illustrate this. Surface modifications induced in lens manufacture are observed to produce not only changes in these value, which may be small, but also changes in the DCA “fingerprint” (slope, undulations, length of plateau). Interestingly, similar changes are induced in the first few hours of lens wear with some lens-patient combinations.Conclusions: Although single parameter contact angles are useful for material characterisation, information of potential clinical interest can be obtained from more detailed analysis of DCA traces.",
author = "Darren Campbell and Sarah Carnell and Gareth Ross and Brian Tighe",
note = "Abstract published on Abstracts / Contact Lens & Anterior Eye 33 (2010), 284-285 DOI http://dx.doi.org/10.1016/j.clae.2010.07.002; British Contact Lens Association ; Conference date: 27-05-2010 Through 30-05-2010",
year = "2010",
language = "English",
pages = "284",

}

Campbell, D, Carnell, S, Ross, G & Tighe, B 2010, 'Another angle on contact lens surface analysis' British Contact Lens Association, Birmingham, United Kingdom, 27/05/10 - 30/05/10, pp. 284.

Another angle on contact lens surface analysis. / Campbell, Darren; Carnell, Sarah; Ross, Gareth; Tighe, Brian.

2010. 284 Poster session presented at British Contact Lens Association, Birmingham, United Kingdom.

Research output: Contribution to conferencePoster

TY - CONF

T1 - Another angle on contact lens surface analysis

AU - Campbell, Darren

AU - Carnell, Sarah

AU - Ross, Gareth

AU - Tighe, Brian

N1 - Abstract published on Abstracts / Contact Lens & Anterior Eye 33 (2010), 284-285 DOI http://dx.doi.org/10.1016/j.clae.2010.07.002

PY - 2010

Y1 - 2010

N2 - Purpose: Dynamic contact angle (DCA) methods have advantages over other contact angle methodologies, not least that they can provide more than single contact angle values. Here we illustrate the use of DCA analysis to provide “fingerprint” characterisation of contact lens surfaces, and the way that different materials change in the early stages of wear.Method: The DCA method involves attaching to a microbalance weighted strips cut from a lens. The strips are then cyclically inserted into and removed from an aqueous solution. Conventionally, readings of force taken from linear portions of the resultant dipping curves are translated into advancing (CAa) and receding contact (CAr) angles. Additionally, analysis of the force versus immersion profile provides a “fingerprint” characterisation of the state of the lens surface.Results: CAa and CAr values from DCA traces provide a useful means of differentiating gross differences in hydrophilicity and molecular mobility of surfaces under particular immersion and emersion conditions, such as dipping rate and dwell times. Typical values for etafilcon A (CAa:63.1; CAr:37) and balafilcon B (CAa:118.4; CAr:36.4) illustrate this. Surface modifications induced in lens manufacture are observed to produce not only changes in these value, which may be small, but also changes in the DCA “fingerprint” (slope, undulations, length of plateau). Interestingly, similar changes are induced in the first few hours of lens wear with some lens-patient combinations.Conclusions: Although single parameter contact angles are useful for material characterisation, information of potential clinical interest can be obtained from more detailed analysis of DCA traces.

AB - Purpose: Dynamic contact angle (DCA) methods have advantages over other contact angle methodologies, not least that they can provide more than single contact angle values. Here we illustrate the use of DCA analysis to provide “fingerprint” characterisation of contact lens surfaces, and the way that different materials change in the early stages of wear.Method: The DCA method involves attaching to a microbalance weighted strips cut from a lens. The strips are then cyclically inserted into and removed from an aqueous solution. Conventionally, readings of force taken from linear portions of the resultant dipping curves are translated into advancing (CAa) and receding contact (CAr) angles. Additionally, analysis of the force versus immersion profile provides a “fingerprint” characterisation of the state of the lens surface.Results: CAa and CAr values from DCA traces provide a useful means of differentiating gross differences in hydrophilicity and molecular mobility of surfaces under particular immersion and emersion conditions, such as dipping rate and dwell times. Typical values for etafilcon A (CAa:63.1; CAr:37) and balafilcon B (CAa:118.4; CAr:36.4) illustrate this. Surface modifications induced in lens manufacture are observed to produce not only changes in these value, which may be small, but also changes in the DCA “fingerprint” (slope, undulations, length of plateau). Interestingly, similar changes are induced in the first few hours of lens wear with some lens-patient combinations.Conclusions: Although single parameter contact angles are useful for material characterisation, information of potential clinical interest can be obtained from more detailed analysis of DCA traces.

M3 - Poster

SP - 284

ER -

Campbell D, Carnell S, Ross G, Tighe B. Another angle on contact lens surface analysis. 2010. Poster session presented at British Contact Lens Association, Birmingham, United Kingdom.