The invention relates to the use of cyclopentane heptan(ene)oic acid, 2-thiocarbamoyloxy and carbamoyloxy as therapeutic agents e.g. as ocular hypotensives. The compounds used in accordance with the invention are represented by the following formula I: ##STR00001## wherein a wavy segments indicate either the alpha (.alpha.) or beta (.beta.) configuration; the dashed bond represents a double bond or a single bond; U, Y, X, R.sup.1, Ar, n, x and y are as defined in the specification.