Hydrogel (Acuvue) lens movement is influenced by the postlens tear film

The determinants of hydrogel lens movement with thin mid-water content lenses may be better understood by taking into account the lubrication properties of the tear film. We assessed lens movement, postlens tear film (PTF) status, and tear meniscus height with 58% water content (Acuvue) lenses worn over 6 h on each of 2 consecutive days. Median lens movement was near zero initially and increased within the first hour to 0.34 and 0.30 mm on days 1 and 2, respectively (Friedman analysis of variance by ranks, days 1 and 2, p < 0.001). The small lens movement at 15 min was related to the increased PTF depletion (Kruskal-Wallis analysis of variance; day 1, p = 0.02; day 2, p = 0.007). In some subjects, lens movement and PTF status co-varied throughout the lens wearing periods. These findings suggest the PTF is a determinant of hydrogel lens movement.