Skip Navigation LinksHome > May 2013 - Volume 39 - Issue 3 > Applicability of Contact Angle Techniques Used in the Analys...
Eye & Contact Lens: Science & Clinical Practice:
doi: 10.1097/ICL.0b013e31828ca174
Review Article

Applicability of Contact Angle Techniques Used in the Analysis of Contact Lenses, Part 1: Comparative Methodologies

Campbell, Darren Ph.D.; Carnell, Sarah Maria M.Eng.; Eden, Russell John M.Sc.

Collapse Box

Abstract

Objectives and Methods:

Contact angle, as a representative measure of surface wettability, is often employed to interpret contact lens surface properties. The literature is often contradictory and can lead to confusion. This literature review is part of a series regarding the analysis of hydrogel contact lenses using contact angle techniques. Here we present an overview of contact angle terminology, methodology, and analysis. Having discussed this background material, subsequent parts of the series will discuss the analysis of contact lens contact angles and evaluate differences in published laboratory results.

Results:

The concepts of contact angle, wettability and wetting are presented as an introduction. Contact angle hysteresis is outlined and highlights the advantages in using dynamic analytical techniques over static methods. The surface free energy of a material illustrates how contact angle analysis is capable of providing supplementary surface characterization. Although single values are able to distinguish individual material differences, surface free energy and dynamic methods provide an improved understanding of material behavior. The frequently used sessile drop, captive bubble, and Wilhelmy plate techniques are discussed. Their use as both dynamic and static methods, along with the advantages and disadvantages of each technique, is explained.

Conclusions:

No single contact angle technique fully characterizes the wettability of a material surface, and the application of complimenting methods allows increased characterization. At present, there is not an ISO standard method designed for soft materials. It is important that each contact angle technique has a standard protocol, as small protocol differences between laboratories often contribute to a variety of published data that are not easily comparable.

© 2013 Contact Lens Association of Ophthalmologists

Login

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.