Glucose significantly improved the mean contrast sensitivity at 12 cycles/degree compared with 0.9 % saline by 0.26 log units ( 95 % confidence interval [ CI ] , 0.13-0 .38 ; P < 0.001 ) and 0.40 log units ( 95 % CI , 0.17-0 .60 ; P < 0.001 ) in the follow-up study .