Effect of phospholipid-containing eye drops on the de-wetting behaviour of soft contact lenses

Abstract

Purpose. The primary objective of the study was to determine differences between in vitro surface de-wetting of soft con- tact lens (SCL) materials out of saline solution, before and after treatment with phospholipid containing rewetting drops. Material and Methods. Fifteen lenses of different SCL mate- rial classes according to ISO 18369 were tested (polymacon, nelfilcon A, ocufilcon D, balafilcon A, somofilcon A, lotrafilcon B). The lenses were rinsed and stored in saline solution to min- imize the effect of the original blister solution. A de-wetting video was captured for every lens using the Keratograph 5M. Afterwards all lenses were soaked in phospholipid containing rewetting solution for 25 hours. The lenses were gently ag- itated by an orbital shaker with a frequency 0.25 Hz, tilting up to 15°. After treatment, all lenses were equilibrated again in saline solution for at least 30 minutes. De-wetting videos were captured again. In vitro “Non-Invasive Keratograph Dry Up Time“ (NIK-DUT) was assessed for a measurement time of 180 s. The results were expressed by the Area Under Curve (AUC) as well as clinical relevant time point to reach 4.82 mm2 de-wetting. Results. The AUC results before and after treatment with phospholipid containing rewetting solution were: polymacon 4870.9 ± 942.7 and 6214.1 ± 932.1, nelfilcon A 4688.0 ± 1065.1 and 6959.8 ± 1081.8, ocufilcon D 3612.6 ± 875.5 and 7042.0 ± 714.3, balafilcon A 4170.4 ± 927.2 and 7385.6 ± 879.8, somofil- con A 4284.50 ± 833.8 and 6762.2 ± 1380.2 and lotrafilcon B, comfilcon A 4973.3 ± 1249.3 and 7415.7 ± 994.8. All differences were statistically significant at a significance level of 0.05 with P<0.001 (Wilcoxon rank sum test). The mean time to reach 4.82 mm2 de-wetting was 19 s. Conclusion. The used phospholipid containing solution did interact with all soft contact lens materials and lead to accelerated in vitro de-wetting. As the de-wetting area of 4.82 mm2 is reached after a typical interblink period for con- tact lens wearers during attentional visual tasks, it is unlikely to expect a drop of the visual acuity by one log line. Keywords Contact Lenses, Dry Eye