The percentage of eyes in which the increase in IOP using a single postwashout IOP differed from the increase in IOP using the mean of @ measurements by more than @ mm Hg was @ % , @ % , @ % , @ % , and @ % when the single measurement was made at @ am , @ pm , @ pm , a randomly chosen single measure of those @ times , and the time closest to that of the prewashout IOP , respectively .