PURPOSE: To obtain an ophthalmic medicine containing a 1,5-benzoxathiepin derivative, exhibiting an excellent local action, reduced in side effect and excellent in safety.

CONSTITUTION: This ophthalmic medicine contains a compound of the formula [R1 and R2 are H, a hydroxyl, a halogen, etc.; R3 and R4 are H, a lower alkyl, etc.; X is H, a lower alkyl, an aryl, etc.; Y is >C=O or >CHOR5; R5 is H, an acyl, etc.; (m) is 0 to 2 and (n) us 1 to 6] or its salt as the active component. Since this local opthalmic medicine exhibits an intraocular pressure-reducing activity by local administration to eyes, it is useful for prevention and remedy of high intraocular pressure diseases causing a high intraocular pressure, glaucoma, etc. In the case where this medicine is used as eye drops for therapy of adult glaucoma, a 0.02 to 2.0w/v% solution of the compound of the formula is administrated in an amount of one to several drops/time, 3 to 6 times per day according to instillation method. In the case of an ophthalmic ointment, the content of the compound of the formula is controlled to 0.02 to 2.0wt.% and the resultant ophthalmic ointment is administrated to the saccus conjunctivae in an amount of 30 to 100mR/one time, 3 to 6 times per day by using an application rod.