首页   按字顺浏览 期刊浏览 卷期浏览 Comparison of the Coulometric and Polarographic Measurement of a High-Dk Hydrogel
Comparison of the Coulometric and Polarographic Measurement of a High-Dk Hydrogel

 

作者: Courtney Morgan,   NOEL BRENNAN,   LARRY ALVORD,  

 

期刊: Optometry and Vision Science  (OVID Available online 2001)
卷期: Volume 78, issue 1  

页码: 19-29

 

ISSN:1040-5488

 

年代: 2001

 

出版商: OVID

 

关键词: oxygen,;transmissibility,;permeability,;coulometric,;polarographic,;fluorosilicone-hydrogel lens

 

数据来源: OVID

 

摘要:

BackgroundInternational Organization for Standardization (ISO) document ISO 9913-1 details procedures for oxygen permeability coefficient (Dk) measurement of hydrogel contact lens materials up to 100 barrer. A draft ISO document 9913-2 describing the coulometric technique states that the recommended procedures are suitable for nonhydrogel materials. New generation hydrogel lens materials exceed 100 barrer, which is outside the scope of both documents.MethodsA range of rigid gas-permeable materials from Dr. W. Benjamin’s standard repository was used as a baseline to assess the accuracy of the polarographic and the coulometric methods. We also measured the permeability of a new generation hydrogel, lotrafilcon A, to explore the suitability of the polarographic and coulometric techniques for high-Dk hydrogel lenses. We modified equipment for both methods that incorporate several improvements including front surface masking to eliminate “edge effect.”ResultsThe coulometric technique provided results similar to those previously reported for the standard rigid gas-permeable materials and yielded relative standard errors typically <10%. The polarographic technique provided results similar to the accepted values for the standard rigid gas-permeable materials Dk <70 barreronlyafter the edge effect correction algorithm was applied. The polarographic results showed poor precision and significant, systematic differences from accepted values for the rigid gas-permeables with Dk >70 barrer.ConclusionsThe coulometric method is preferable for the measurement of contact lens materials with permeability >70 barrer. The coulometric method was successfully modified to include hydrogels.

 

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