The invention relates to the use of novel cyclohexyl analogues of E-type prostaglandins as EP₄ 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: ##STR1##

wherein the wavy segments represent or bond, dashed line represents the presence or absence of a bond W, Y, Z, R, R¹, R² and R³ are as defined in the specification.