Microcyst response to high Dk/t silicone hydrogel contact lenses

Purpose: To investigate the microcyst response to extended wear (EW) with h igh oxygen transmissible (Dk/t) silicone hydrogel lenses. Methods: Microcys ts were monitored for 12 months in subjects weaving low Dk/t hydrogel lense s on a 6-night EW schedule or high Dk/t hydrogel lenses on a 30-night EW sc hedule. Subjects wearing low Dk/t lenses transferred to the high Dk/t EW le nses and schedule after 12 months and were monitored for a further 6 months . Results: The mean number of microcysts did not deviate from baseline in t he high Dk/t group. Microcysts in the low Dk/t group increased over 12 mont hs, and move microcysts were observed in low Dk/t lens wearers compared wit h high Dk/t lens wearers after 3 months. Microcysts increased in 50% of sub jects 1 week after transfer to high Dk/t lenses and returned to baseline le vels seen with high Dk/t lens wear within 3 months. Conclusions: EW with hi gh Dk/t silicone hydrogel lenses did not cause an increase in microcyst num bers. It is not necessary to discontinue lens wear with patients who transf er from low to high Dk/t lenses because the increase in microcysts is trans itory. This result has implications for practitioners when fitting and asse ssing the success of high Dk/t hydrogel lenses.