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:

Five-year follow-up of the Fluorouracil Filtering Surgery Study . The Fluorouracil Filtering Surgery Study Group . PURPOSE To determine the efficacy and safety of subconjunctival 5- fluorouracil injections after trabeculectomy in patients with poor prognoses , to determine risk factors for surgical failure and to examine the relationship of intraocular pressure and visual function . METHODS In this multicenter clinical trial , 213 patients with previous cataract surgery or previous failed filtering surgery were randomly assigned to receive either trabeculectomy alone or trabeculectomy with postoperative subconjunctival 5-fluorouracil injections . Measurements of intraocular pressure , visual acuity , and visual fields were performed throughout the five years , with the clinician masked to the treatment group . Failure was defined as a reoperation to control intraocular pressure or an intraocular pressure greater than 21 mm Hg at or after the first-year examination . RESULTS Fifty-four ( 51 % ) of the 105 eyes in the 5-fluorouracil group and 80 ( 74 % ) of the 108 eyes in the standard filtering surgery group were classified as failures ( P < .001 , Mantel-Cox survival analysis ) . Risk factors for failure include high intraocular pressure , a short time interval after the last procedure involving a conjunctival incision , the number of procedures with conjunctival incisions , and Hispanic ethnicity . Patients in both treatment groups with controlled intraocular pressures were more likely to maintain visual acuity . Patients in the 5-fluorouracil group had a higher risk of late-onset bleb leaks ( 9 % nine of 105 ) than those in the standard filtering surgery group ( 2 % two of 108 ) ( P = .032 , Fisher 's exact test ) . CONCLUSIONS We recommend the use of subconjunctival 5-fluorouracil after trabeculectomy in eyes after previous cataract surgery or unsuccessful filtering surgery , but caution against its routine use in patients with good prognoses .
{"Intervention": ["postoperative subconjunctival 5-fluorouracil injections", "subconjunctival 5- fluorouracil injections", "trabeculectomy", "subconjunctival 5-fluorouracil", "5-fluorouracil", "Fluorouracil Filtering Surgery"], "Outcome": ["efficacy", "high intraocular pressure", "visual acuity", "visual fields", "intraocular pressure", "late-onset bleb leaks", "visual function", "safety"], "Participant": ["patients with poor prognoses , to determine risk factors for surgical failure and to examine the relationship of intraocular pressure and visual function ."]}