The participants in these subgroups were randomized to receive ketorolac tromethamine 0.5 % in 1 eye and placebo ( ofloxacin 0.3 % ) in the fellow eye ( Group 2A ) , proparacaine hydrochloride 0.5 % in 1 eye and placebo in the fellow eye ( Group 2B ) , or ketorolac tromethamine 0.5 % in 1 eye and placebo in the fellow eye , followed 10 minutes later by 1 drop of proparacaine hydrochloride 0.5 % in both eyes ( Group 2C ) .