- Email: [email protected]
A closer look at dynamic contact angle (DCA) analysis: angles, areas and advancing traces
Abstracts / Contact Lens & Anterior Eye 35S (2012) e1–e32
A (29◦ ; 31◦ ), lotrafilcon A (30◦ ; 35◦ ), lotrafilcon B (27◦ ;35◦ ), and comfilcon A (25◦ ;33◦ ) were statistically lower than all the other lens materials (p < 0.05). Conclusions: Advancing and receding CAs of the CIBA Vision lens materials, including the newest SH DD material (delefilcon A) as well as CooperVision’s comfilcon A, were significantly lower than the CAs for the other lens materials. The impact of low advancing and receding CAs on clinical comfort requires further investigation. Financial support for this study was funded by Alcon. http://dx.doi.org/10.1016/j.clae.2012.08.039 37 A novel, non-destructive method to measure the modulus of soft lens materials Alexander Leube 1,∗ , Sebastian Marx 2 , Wolfgang Sickenberger 2,3 1
Student, Jena, Germany JenVis Research Jena, Jena, Germany 3 University of Applied Science Jena, Germany ∗ E-mail address: [email protected] (A. Leube) 2
Purpose: The aim of this study is to develop and to test a novel, non-destructive method to evaluate the modulus of common, soft contact lens materials. In course of the development potential confounding factors should be examine. Method: A micro-hardness tester (Fischerscope HM2000) was used the first time to measure the modulus of five different monthly and three different daily disposable lenses according to the instrumented indentation test (ISO 14577). The lenses were soaked for 24 hours in saline solution. To examine the confounding factors measurements with three different fluids and contact lenses of different thicknesses were performed. Results: The comparison between the modulus of the measured contact lenses and the reference values shows in every case significant differences (p < 0.001, t-test). The coefficient of variation ranged from 2% up to 35%. The analysis of the confounding factors shows that the achieved modulus measured in saline solution is significant lower in comparison to a conditioned solution (p < 0.001, t-test) and a blister solution (p = 0.03, t-test). Measurement of thinner lenses resulted in higher modulus values (rmin = 0.78, p = 0.24; rmax = 0.99, p = 0.03). Conclusions: The measuring under hydrated conditions of the modulus of common, soft contact lenses with the indentation test is possible. The study describes different confounding factors and shows first comparable values of common, soft contact lens materials. http://dx.doi.org/10.1016/j.clae.2012.08.040 38 Differential contact angle and protein/lipid deposition profiles on a novel daily disposable contact lens material Mohinder M. Merchea ∗ , Patricia Harmon, Michael X. Liu, Peter Maziarz Bausch+Lomb, Rochester, USA E-mail address: [email protected] (M.M. Merchea)
∗
Purpose: Sessile drop contact angle and chromatographic techniques were used to assess the surface wettability and deposition characteristics of a novel CL material compared to commercially available daily disposable contact lenses. Method: The sessile drop contact angle was measured for a novel lens material, narafilcon B (AV TruEye) and etafilcon A (AV
e13
Moist), at two different points on each lens. Lenses were analysed both directly out of the packaging solution without rinsing, as well as after being soaked for 18 h in an artificial tear fluid (ATF). Results: The test lens material demonstrated a more wettable surface based on a statistically significantly lower sessile drop water contact angle than both narafilcon B (p = 9.60 × 10−5 ) and etafilcon A (p = 5.88 × 10−6 ) directly out of the blister. After soaking in ATF, the test lens material had a statistically significantly lower contact angle than narafilcon B (p = 2.34 × 10−3 ) and etafilcon A (p = 6.25 × 10−6 ). The test lens material also demonstrated the lowest overall deposition level after overnight exposure to an ATF. GC and HPLC demonstrated 13 g/lens combined lipids and proteins were deposited on the test lens material, which is statistically significantly lower than the 90 g/lens (p = 7.39 × 10−6 ) deposited on narafilcon B and 33 g/lens (p = 2.81 × 10−5 ) deposited on etafilcon A. Conclusions: The test lens was statistically significantly more surface wettable than either narafilcon B or etafilcon A and had fewer combined lipid and protein deposits. http://dx.doi.org/10.1016/j.clae.2012.08.041 39 A closer look at dynamic contact angle (DCA) analysis: angles, areas and advancing traces Russell J. Eden ∗ , Darren Campbell, Amandeep Panaser, Brian J. Tighe Aston University, Birmingham, UK E-mail address: [email protected] (R.J. Eden)
∗
Purpose: In addition to the advancing contact angle (CAa), receding contact angle (CAr) and contact angle hysteresis DCA generates unique material profiles. This information can be used to ascertain how surfaces of materials can change, for example in response to modification processes or during wear. Method: DCA involves the cyclic immersion of a material strip into a probe solution. Readings of force are taken from the wavefronts and translated into CAa and CAr. This also gives a characteristic ‘profile’ which depicts subtle changes in surface properties of the lens sample. These material ‘profiles’ were used as a comparative tool to distinguish between surfaces (control, modified and worn). Profile analysis was based on areas, zero mass/mg intercept point (ZIP) and advancing wavefronts. Results: Analysis of the material profiles showed differences in wettability, hydration and reorientation processes. For example senofilcon A (Acuvue Oasys) was modified using two separate methods. This produced surfaces with similar CAa and CAr. Analysis of the area difference between the advancing traces (2109 mass/mg2 ) and the ZIPs (5.62 mm and 2.48 mm) indicated one lens had different hydrophilicity, and a different reorientation and dehydration pattern to the other lens. 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 ‘profiles’. Area, zero mass/mg intercept and advancing wavefront analysis provide complementary data to CA values and are able to emphasise differences in surface characteristics between lenses with similar CA values. http://dx.doi.org/10.1016/j.clae.2012.08.042
A (29◦ ; 31◦ ), lotrafilcon A (30◦ ; 35◦ ), lotrafilcon B (27◦ ;35◦ ), and comfilcon A (25◦ ;33◦ ) were statistically lower than all the other lens materials (p < 0.05). Conclusions: Advancing and receding CAs of the CIBA Vision lens materials, including the newest SH DD material (delefilcon A) as well as CooperVision’s comfilcon A, were significantly lower than the CAs for the other lens materials. The impact of low advancing and receding CAs on clinical comfort requires further investigation. Financial support for this study was funded by Alcon. http://dx.doi.org/10.1016/j.clae.2012.08.039 37 A novel, non-destructive method to measure the modulus of soft lens materials Alexander Leube 1,∗ , Sebastian Marx 2 , Wolfgang Sickenberger 2,3 1
Student, Jena, Germany JenVis Research Jena, Jena, Germany 3 University of Applied Science Jena, Germany ∗ E-mail address: [email protected] (A. Leube) 2
Purpose: The aim of this study is to develop and to test a novel, non-destructive method to evaluate the modulus of common, soft contact lens materials. In course of the development potential confounding factors should be examine. Method: A micro-hardness tester (Fischerscope HM2000) was used the first time to measure the modulus of five different monthly and three different daily disposable lenses according to the instrumented indentation test (ISO 14577). The lenses were soaked for 24 hours in saline solution. To examine the confounding factors measurements with three different fluids and contact lenses of different thicknesses were performed. Results: The comparison between the modulus of the measured contact lenses and the reference values shows in every case significant differences (p < 0.001, t-test). The coefficient of variation ranged from 2% up to 35%. The analysis of the confounding factors shows that the achieved modulus measured in saline solution is significant lower in comparison to a conditioned solution (p < 0.001, t-test) and a blister solution (p = 0.03, t-test). Measurement of thinner lenses resulted in higher modulus values (rmin = 0.78, p = 0.24; rmax = 0.99, p = 0.03). Conclusions: The measuring under hydrated conditions of the modulus of common, soft contact lenses with the indentation test is possible. The study describes different confounding factors and shows first comparable values of common, soft contact lens materials. http://dx.doi.org/10.1016/j.clae.2012.08.040 38 Differential contact angle and protein/lipid deposition profiles on a novel daily disposable contact lens material Mohinder M. Merchea ∗ , Patricia Harmon, Michael X. Liu, Peter Maziarz Bausch+Lomb, Rochester, USA E-mail address: [email protected] (M.M. Merchea)
∗
Purpose: Sessile drop contact angle and chromatographic techniques were used to assess the surface wettability and deposition characteristics of a novel CL material compared to commercially available daily disposable contact lenses. Method: The sessile drop contact angle was measured for a novel lens material, narafilcon B (AV TruEye) and etafilcon A (AV
e13
Moist), at two different points on each lens. Lenses were analysed both directly out of the packaging solution without rinsing, as well as after being soaked for 18 h in an artificial tear fluid (ATF). Results: The test lens material demonstrated a more wettable surface based on a statistically significantly lower sessile drop water contact angle than both narafilcon B (p = 9.60 × 10−5 ) and etafilcon A (p = 5.88 × 10−6 ) directly out of the blister. After soaking in ATF, the test lens material had a statistically significantly lower contact angle than narafilcon B (p = 2.34 × 10−3 ) and etafilcon A (p = 6.25 × 10−6 ). The test lens material also demonstrated the lowest overall deposition level after overnight exposure to an ATF. GC and HPLC demonstrated 13 g/lens combined lipids and proteins were deposited on the test lens material, which is statistically significantly lower than the 90 g/lens (p = 7.39 × 10−6 ) deposited on narafilcon B and 33 g/lens (p = 2.81 × 10−5 ) deposited on etafilcon A. Conclusions: The test lens was statistically significantly more surface wettable than either narafilcon B or etafilcon A and had fewer combined lipid and protein deposits. http://dx.doi.org/10.1016/j.clae.2012.08.041 39 A closer look at dynamic contact angle (DCA) analysis: angles, areas and advancing traces Russell J. Eden ∗ , Darren Campbell, Amandeep Panaser, Brian J. Tighe Aston University, Birmingham, UK E-mail address: [email protected] (R.J. Eden)
∗
Purpose: In addition to the advancing contact angle (CAa), receding contact angle (CAr) and contact angle hysteresis DCA generates unique material profiles. This information can be used to ascertain how surfaces of materials can change, for example in response to modification processes or during wear. Method: DCA involves the cyclic immersion of a material strip into a probe solution. Readings of force are taken from the wavefronts and translated into CAa and CAr. This also gives a characteristic ‘profile’ which depicts subtle changes in surface properties of the lens sample. These material ‘profiles’ were used as a comparative tool to distinguish between surfaces (control, modified and worn). Profile analysis was based on areas, zero mass/mg intercept point (ZIP) and advancing wavefronts. Results: Analysis of the material profiles showed differences in wettability, hydration and reorientation processes. For example senofilcon A (Acuvue Oasys) was modified using two separate methods. This produced surfaces with similar CAa and CAr. Analysis of the area difference between the advancing traces (2109 mass/mg2 ) and the ZIPs (5.62 mm and 2.48 mm) indicated one lens had different hydrophilicity, and a different reorientation and dehydration pattern to the other lens. 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 ‘profiles’. Area, zero mass/mg intercept and advancing wavefront analysis provide complementary data to CA values and are able to emphasise differences in surface characteristics between lenses with similar CA values. http://dx.doi.org/10.1016/j.clae.2012.08.042