Contact Angle Measurement Methods for Soft Contact Lens Wettability

Abstract

Purpose: This study investigated a suitable contact angle measurement method for evaluating wettability in soft contact lenses. Methods : Based on the method of measuring the contact angle of RGP contact lenses specified in the ANSI Z80.20-2004 standard, the contact angle between the RGP lens and the soft contact lens was compared and analyzed through the sessile drop and captive bubble methods. In addition, the suitable contact angle measurement method for soft contact lenses were confirmed by comparing the contact angle changes over time and the measurement results distribution. Results : In the RGP lens, the contact angle measured by the captive bubble method was lower than that measured by the sessile drop method. In the soft contact lens, the contact angle measured by the captive bubble method was lower than that of the sessile drop method in the same way as the RGP contact lens. The sessile drop method was more affected by external influences than the captive bubble method. Conclusions : As for the wettability measurement method of soft contact lenses, the captive bubble method, less affected by external factors like the RGP lenses, is considered more accurate than the sessile drop method.