a flexible ocular insert device adapted for the controlled sustained release of an ophthalmic drug into the eye . in one embodiment , the device includes an elongated body of a polymeric material in the form of a rod or tube containing a pharmaceutically active ingredient and with at least two anchoring protrusions extending radially outwardly from the body . the device has a length of at least 8 mm and the diameter of its body portion including the protrusions does not exceed 1 . 9 mm . the sustained release mechanism may , for example , be by diffusion or by osmosis or bioerosion . the insert device is advantageously inserted into the upper or lower fornix of the eye so as to be independent of movement of the eye by virtue of the fornix anatomy . the protrusions may be of various shapes such as , for example , ribs , screw threads , dimples or bumps , truncated cone - shaped segments or winding braid segments . in a further embodiment , the polymeric material for the body is selected as one which swells in a liquid environment . thus a device of smaller initial size may be employed . the present insert device is of a size and configuration such that , upon insertion into the upper or lower fornix , the device remains out of the field of vision so as to be well retained in place and imperceptible by a patient over a prolonged period of use . the device can be retained in the upper or lower fornix for 7 to 14 days or longer .