Agent for reducing eye strain.

AN EXCELLENT TENSION REDUCING AGENT EYE AND / OR THERAPEUTIC AGENT FOR glaucoma eyedrops containing the compound shown below, a salt thereof and / or ester thereof. [SUP R {1}: alkyl, alkenyl, group of the formula R {SUP, 5} -AB- (R SUP {5}: H, alkyl, cycloalkyl, acyl; A: O, S; B: single bond, alkylene); R {SUP, 2}: alkyl, alkenyl, a group of formula C (R {SUP, 6} (R {SUP, 7}) (R {SUP, 8}) (R {SUP, 6}: OH, alkoxy; R {SUP, 7}, {R SUP, 8}: H, alkyl, alkenyl, alkynyl, cycloalkyl, aryl, ARALKILO); R {SUP, 3}: COOH, a group of formula -CON (R { SUP, 9}) (R {SUP, 10}) (R {SUP, 9}, {R SUP, 10}: H, optionally substituted alkyl); R SUP {4}: COOH, COCOOH, tetrazole]