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:

Boston Keratoprosthesis Type 1: A Randomized Controlled Trial of Fresh versus Frozen Corneal Donor Carriers with Long-Term Follow-up To compare the long-term clinical outcomes of fresh versus frozen corneal graft carriers for the Boston Keratoprosthesis type 1 (B-KPro). Prospective, single-center, nonblinded, randomized controlled trial. All participants were followed through the initial study protocol of 24 months and were approached to enter an extension phase, with continuing follow-up visits to 60 months. All patients undergoing B-KPro surgery between October 2008 and December 2009 by a single experienced surgeon at the Centre Hospitalier de l'Université de Montréal using an allograft carrier were considered. Patients were excluded if they had previously undergone B-KPro implantation. Participants were randomized individually to receive a B-KPro using a frozen or a fresh corneal graft carrier on the basis of tissue availability on the day of surgery, as determined by the local eye bank. The primary outcome measure was device retention at 24 and 60 months. Secondary outcome measures included surgical feasibility, visual acuity (VA), and complications. Thirty-seven eyes of 37 patients were enrolled in the initial study protocol, with 19 eyes randomized to fresh and 18 to frozen carrier grafts. Thirty-six eyes were followed through to 24 months, with 1 lost to follow-up. Of these, 26 were enrolled in the extension (11 eyes with a frozen and 15 eyes with a fresh carrier graft). There were no differences in the baseline characteristics of patients enrolled in the extension phase versus those who were not. At 60 months, median corrected distance VA) in the fresh group had improved to 20/150 from a baseline of counting fingers, whereas the frozen group improved to 20/400 from a baseline of hand motions. Device retention was 100% at 24 months and 96% at 60 months. There were no significant differences in the rate of complications between groups. Fresh and frozen corneal donors offer similar clinical outcomes when used as carriers for the B-KPro, with no significant differences in device retention, visual rehabilitation, or rates of complications at 24 or 60 months.
{"AnatomicalStructure": ["eyes", "corneal graft carrier", "tissue", "allograft carrier", "carrier grafts", "carrier graft", "carriers"], "Bacterium": [], "BiologicFunction": ["complications"], "BiomedicalOccupationOrDiscipline": [], "BodySubstance": [], "BodySystem": [], "Chemical": [], "ClinicalAttribute": ["visual acuity", "VA"], "Eukaryote": [], "Finding": ["device retention", "Device retention", "improved", "surgical feasibility", "visual rehabilitation", "randomized"], "Food": [], "HealthCareActivity": ["B-KPro surgery", "surgery", "follow-up visits", "Follow-up", "follow-up", "implantation"], "InjuryOrPoisoning": [], "IntellectualProduct": ["study protocol"], "MedicalDevice": ["Boston Keratoprosthesis type 1", "Boston Keratoprosthesis Type 1", "B-KPro"], "Organization": ["eye bank", "Hospitalier de l\u0027Universit\u00e9 de Montr\u00e9al"], "PopulationGroup": ["participants", "corneal donors", "Participants"], "ProfessionalOrOccupationalGroup": ["experienced surgeon"], "ResearchActivity": ["Randomized Controlled Trial", "randomized controlled trial.", "randomized"], "SpatialConcept": [], "Virus": []}