You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

A dose-response study of the effect of levobunolol on ocular hypertension . We conducted a randomized , double-masked , dose-response study of the ocular hypotensive effect of the beta-adrenergic blocker , levobunolol . A single drop of placebo or levobunolol ( at concentrations of 0.03 % , 0.3 % , 0.6 % , 1 % , and 2 % ) was administered to one eye of each of 48 patients with ocular hypertension . The 0.3 % and 0.6 % concentrations decreased intraocular pressure significantly from baseline levels compared to placebo at one , two , and four hours after treatment . The 1 % and 2 % concentrations decreased intraocular pressure significantly from baseline compared to placebo at one , two , four , six , eight , and 12 hours after administration . No objective or subjective side effects were noted , and no substantial changes in visual acuity , pupil diameter , pulse rate , or blood pressure were recorded during the study . These results appear to justify long-term studies of levobunolol for the treatment of increased intraocular pressure .
{"Intervention": ["placebo", "levobunolol"], "Outcome": ["substantial changes in visual acuity , pupil diameter , pulse rate , or blood pressure", "intraocular pressure significantly", "objective or subjective side effects", "intraocular pressure", "ocular hypotensive effect", "ocular hypertension ."], "Participant": ["48", "ocular hypertension"]}