Two studies were carried out in volunteers without any abnormal ocular conditions to assess the effects and safety of an ophthalmic preparation of oxymetazoline (0.025%). In the first study in which oxymetazoline was compared with placebo and phenylephrine, the results of infra-red electronic pupillography showed that oxymetazoline in therapeutic doses had no effect on pupil size or near point recession. The second study, which was a double-blind forced choice comparison of two different formulations against placebo and 1% naphazoline, showed from assessments of the degree of ocular discomfort and hyperaemia that oxymetazoline was well tolerated and the subjects preferred oxymetazoline in a boric acid rather than in a phosphate solution.