PURPOSE: To obtain the rod for preventing the outflow of the tears which is less fluctuated in a dissolving speed by using a polymer having the repeating unit expressed by general formula.

CONSTITUTION: The polymer consisting of the formula (R is hydrogen or methyl; (n) is 1 or 2; at least one piece of R is hydrogen when (n) is 2) is obtd. by subjecting a monomer to a ring opening polymn. at 75 to 130°C in the presence of an org. metallic catalyst, such as diethyl zinc as shown in, for example, US Patent Specification No. 4052988. The resulted polymer is melt spun by using a plunger extruder, etc., and is cooled to solidify; thereafter, the extruded polymer is cut to a desired length, by which the rod for preventing the outflow of the tears is obtd. A dry eye symptom is decreased by using such rod for preventing the outflow of the tears. Since the dissolution speed is uniform, the management of an insertion schedule is easy and in addition, the unstability as to bioaffinity is lessened.