The invention relates to the use of novel cyclohexyl analogues of E-type prostaglandins as EP.sub.4 agonists, in general, and, in particular as ocular hypotensives. The cyclohexyl analogues used in accordance with the invention are represented by the following formula I: ##STR00001## wherein the wavy segments represent .alpha. or .beta. bond, dashed line represents the presence or absence of a bond W, Y, Z, R, R.sup.1, R.sup.2 and R.sup.3 are as defined in the specification.