Purchase this article with an account.
K. Maruyama, N. Ykoi, S. Kinoshita; New Interference-Based in vitro Technique Applicable to the Assessment of Wettability of Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5388.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
To investigate the usefulness of a new, interference-based in vitro technique for assessing the wettability of various contact lenses (CLs) by use of an interferometer (DR-1TM; Kowa Co., Ltd., Tokyo).
Various CLs including the rigid gas permeable CL (RGPCL), soft CL (SCL) with high water content (SCL-H), SCL with low water content (SCL-L), and silicone hydrogel SCL (SiHSCL) were soaked in saline for 24 hours and then placed on hemispherical-shaped resin holders and observed independently under standardized conditions (air temperature: 25°C, relative humidity: 40%) by use of the interferometer. To assess the liquid layer on the CLs, the beginning time (Bt) that a dry spot appeared and the interferometric contact angle (ICA) of the liquid layer at the interface between the dry spot and liquid layer were both measured (10 lenses tested for each CL type, 50 lenses total). The ICAs were calculated with a slope consisting of an X axis representing the distance between the dry spot and interference color, and a Y axis representing the liquid-thickness-converted interference color using Newton’s color scale.
The Bt of the RGPCL, SCL-H, SCL-L, and SiHSCL were 4.2 ± 4.6, 27.8 ± 6.6, 31.6 ± 4.1, and 29.5 ± 8.1 (all in seconds), respectively, showing a significantly shorter Bt in the RGPCL as compared with SCLs (p < 0.0001, in every two comparisons). The correspondent ICAs were 0.111 ± 0.016, 0.074 ± 0.025, 0.068 ± 0.019, and 0.047 ± 0.014 (all in degrees), respectively. The RGPCL showed a significantly higher ICA than those of SCLs (p < 0.0001, in every two comparisons), and the SiHSCL showed a significantly lower ICA than those of the SCL-H (p < 0.05) and SCL-L (p < 0.01). However, no significant differences in ICA were found between the SCL-H and SCL-L (p = 0.4505).
Our new in vitro technique using an interferometer proved useful for assessing the wettability of CL surfaces and for mimicking the wettability performance of CLs during actual use on the eye. Further work is required to explore the relationship between the wettability of CLs and subjective symptoms.
This PDF is available to Subscribers Only