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: ["HealthCareActivity", "InjuryOrPoisoning", "BodySubstance", "IntellectualProduct", "AnatomicalStructure", "SpatialConcept", "Chemical", "Bacterium", "MedicalDevice", "Organization", "BiomedicalOccupationOrDiscipline", "Finding", "BiologicFunction", "Virus", "ResearchActivity", "ClinicalAttribute", "PopulationGroup", "Eukaryote", "BodySystem", "Food", "ProfessionalOrOccupationalGroup"].

Please return the output as a JSON object of the format: {"Virus": ["HIV", ...], "Bacterium": ["MRSA", ...], "AnatomicalStructure": ["Lung", ...], "BodySystem": ["CNS", ...], "BodySubstance": ["Serum", ...], "Finding": ["Headache", ...], "InjuryOrPoisoning": ["Fracture", ...], "BiologicFunction": ["Death", ...], "HealthCareActivity": ["Biopsy", ...], "ResearchActivity": ["Clinical trial", ...], "MedicalDevice": ["Lenses", ...], "SpatialConcept": ["Camps", ...], "BiomedicalOccupationOrDiscipline": ["Forensic medicine", ...], "Organization": ["WHO", ...], "ProfessionalOrOccupationalGroup": ["Provider", ...], "PopulationGroup": ["Swimmers", ...], "Chemical": ["Gold", ...], "Food": ["Rice", ...], "IntellectualProduct": ["RPAM", ...], "ClinicalAttribute": ["Biomarker", ...], "Eukaryote": ["Dogs", ...]}. 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 pilot study of intraocular lens explantation in 69 eyes in Chinese patients To study the effects of intraocular lens (IOL) explantation and demographic characteristics. Retrospective non-comparative case series. Clinical data recorded from patient charts included the following: demographic, preoperative and postoperative characteristics; complications; surgical methods, and changes in visual acuity. A total of 69 eyes in 67 Chinese patients who received IOL explants were studied. The patients ' mean age at the time of explantation was 46.1 years old [SD 22.5 (6-85)], and 37 patients were female (55.2%). Regarding employment, 47.8% were farmers, 23.9% were retired, 16.4% were students, 4.5% were unemployed, 3% were workers, and 4.5% were other (including staff members, teachers and officers). The main reasons for explantation were dislocation / decentration in 41 cases (59.4%) and retinal detachment in 10 cases (14.5%). The third most prevalent cause was incorrect lens power in 7 eyes (10.1%). The remaining reasons were endophthalmitis in 6 cases (8.7%), posterior capsular opacity in 3 eyes (4.3%), and impacting retinal surgery operation in 2 cases (2.9%). The main comorbidities were high myopia in 18 eyes (26.1%), trauma in 8 eyes (11.6%), retinal detachment in 6 eyes (8.7%), congenital cataracts in 8 eyes (11.6%), and Marfan's syndrome in 2 eyes (2.9%). The mean time from implantation to explantation was 4.0y [SD 4.2 (0.005-15)]. Treatment after explantation included posterior chamber IOL implantation in 44 eyes (63.8%) and aphakia in 25 eyes (36.2%). After surgery, the best corrected visual ability (BCVA) was improved in 50 cases (72.5%), including 28 patients (40.6%) in whom visual ability was improved by more than two lines. Dislocation / decentration is the main cause for explantation, and high myopia is a main risk factor. Posterior chamber IOL implantation remains the most elected treatment after explantation.
{"AnatomicalStructure": ["eyes", "aphakia", "congenital cataracts"], "Bacterium": [], "BiologicFunction": ["retinal detachment", "Marfan\u0027s syndrome", "high myopia", "posterior capsular opacity", "complications", "endophthalmitis"], "BiomedicalOccupationOrDiscipline": [], "BodySubstance": [], "BodySystem": [], "Chemical": [], "ClinicalAttribute": ["visual ability"], "Eukaryote": [], "Finding": ["BCVA", "main risk factor", "incorrect lens power", "decentration", "best corrected visual ability", "unemployed", "After surgery"], "Food": [], "HealthCareActivity": ["retinal surgery operation", "IOL explants", "intraocular lens (IOL) explantation", "explantation", "Posterior chamber IOL implantation", "visual acuity", "treatment after explantation", "intraocular lens explantation", "posterior chamber IOL implantation", "Treatment after explantation", "preoperative"], "InjuryOrPoisoning": ["Dislocation", "trauma", "dislocation"], "IntellectualProduct": ["Clinical data"], "MedicalDevice": [], "Organization": [], "PopulationGroup": ["Chinese", "workers", "students"], "ProfessionalOrOccupationalGroup": ["farmers", "retired", "teachers"], "ResearchActivity": ["non-comparative case series", "pilot study"], "SpatialConcept": [], "Virus": []}