Abstract
Purpose :
Lens surface properties can contribute to improved contact lens comfort. Herein, in-vitro lens surface characteristics of a novel silicone hydrogel contact lens (SHCL) of verofilcon A and a traditional SHCL of narafilcon A were assessed by both sessile drop contact angle (SDCA) and coefficient of friction (CoF).
Methods :
10 lenses each of verofilcon A and narafilcon A were assessed using both SDCA and a micro-tribometer. Prior to measurement, study lenses were prepared to remove package solution components by using 20 mL of saline solution. This step was repeated until the surface tension demonstrated they were free of surfactants. Each study lens was placed into the cycling machine for 1, 2, 3, 4, 6, 8, 10, 12, 14 and 16 hours (repetitive cycles of 1 sec in saline solution and 10 sec in air). The lens holder was positioned directly beneath the dosing needle of the micro syringe on the sample holder stage of the SDCA equipment. A 3 μL drop of phosphate buffer solution (PBS) was formed on the tip of the dosing needle. Micro-tribometer assessment was performed at both 0.1mm/s and 8cm/s sliding speed with artificial tear solution including lysozyme and PBS. For frictional aging, 50 tribometer cycles were assessed after the saline/air cycling. Statistical analyses were performed using two sample t-test.
Results :
For SDCA at 16 hours, verofilcon A was 42.5° and narafilcon A was 91.4°, verofilcon A was superior to narafilcon A including remaining assessment hour (p<0.0001). CoF at 8cm/s sliding speed after 50 tribometer cycles and 16 hours showed verofilcon A was 0.8667 and narafilcon A was 1.5251 (p<0.001). Assessment after 1 hour to 14 hours also showed verofilcon A was superior to narafilcon A (p<0.001). CoF without the 50 cycle frictional aging at both 8cm/s and 0.1mm/s sliding speed showed statistical differences of verofilcon A compared to narafilcon A at 16 hours (each p<0.0001).
Conclusions :
This is the first in-vitro study for both SDCA and CoF on lens surface assessment with multiple hour blink emulation between verofilcon A and narafilcon A. SMARTSURFACE® Technology in verofilcon A maintained excellent lens surface properties in an assessment of both SDCA and CoF.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.