Abstract
Purpose :
To evaluate the lubricating effect of eye drops and hyaluronic acid on contact lenses based on the blinking velocity using a pendulum tester.
Methods :
A new pendulum tester was developed to measure the coefficient of friction (CoF). To mimic the ocular physiologic environment, the load was applied by the pendulum weight of 17.2 g (pressure on the contacted surface, 1.0 kPa) on the counter surface, and the sliding velocity was set to a maximal 88.6 mm/sec. All tests were performed with silicon hydrogel daily disposable contact lens (narafilcon A) (n = 10 for each eye drop; n = 9 for hyaluronic acid); the lubricants were saline, a commercially available artificial tear; 0.1% and 0.3% hyaluronic acid commercial eye drops, and dissolved hyaluronan solution (HA). The concentrations of the HAs were 0.05, 0.1, 0.2, 0.3, 0.4, and 0.5% (w/v) in distilled water. The kinetic viscosity of each lubricant was measured using an Ubbelohde viscometer (SU, Sibata, Japan). The temperature (25.3 ± 0.6°C) and humidity (56 ± 3.5%) in the measurement room were maintained at constant levels. The Steel-Dwass test was used to assess the significant differences in the CoF of each eye drop.
Results :
The CoF of the 0.1% HA eye drop was 0.038 ± 0.003, which increased significantly (Steel-Dwass, p ＜ 0.05) to 0.046 ± 0.005 with the 0.3% HA eye drop. The CoFs of the HA with the concentration of 0.1%, 0.2%, and 0.5% were 0.033 ± 0.003, 0.038 ± 0.003, and 0.063 ± 0.02, respectively. The viscosity of HAs increased with the concentration, as 3.1 mPas at the 0.1% concentration and 125.4 mPas with the 0.5% concentration.
Conclusions :
It was shown that pendulum method is useful for the assessment of the lubricating ability in eye drop on a contact lens. HA used as the lubricant on soft contact lenses showed the maximum effect when the concentration of HA was 0.1%.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.