Recovery from hyperemia after overnight wear of low and high transmissibility hydrogel lenses

Purpose. To measure the limbal vascular response after 8 hours of eye closu re while wearing high and low permeability lenses compared to control eyes without lenses. Method. Twenty neophyte participants wore lotrafilcon A silicone hydrogel l enses (HDk; Dk = 140) or etafilcon A hydrogel lenses (LDk; Dk = 18). On two different nights the lenses were randomly worn for 8 hours during sleep in the right eyes only. Left eyes were non-lens wearing controls. Biomicrosco pic images of the temporal limbal area were videotaped at baseline, on eye opening and every 20 minutes for 3 hours. A masked observer graded digitize d images of the limbal area. Results. On waking and after lens removal there were no differences in hype remia between the HDk and LDk lens wearing eyes. There were also no differe nces at any time between the HDk lens wearing eyes and their control eyes ( p > 0.05). On waking the eyes wearing the LDk lens were more hyperemic comp ared to baseline (p < 0.001) and compared to their control eyes at 20 (p < 0.001) and 180 minutes (p = 0.01), indicating slower recovery from hyperemi a. The HDk lens wearing eyes recovered to their baseline levels by 180 minu tes (p = 0.99), compared to the LDk lens wearing eyes, which had not recove red to baseline levels by 180 minutes (p = 0.04). Conclusion. The reduction in hyperemia over time of the HDk lens wearing ey es was the same as the controls. The LDk lens wearing eyes were more hypere mic than the controls on waking and the reduction in hyperemia over time wa s slower. This suggests that the slower recovery from hyperemia may be affe cted by the lower oxygen transmissibility of the LDk lens.