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Francisco J Rodriguez, Mariana Cabrera, Marcela Lonngi, Cristina Gabela, Maria Teresa Daza; A new orbital implant model of high density porous polyethylene: First animal model using OMNIPOR.. Invest. Ophthalmol. Vis. Sci. 2016;57(12):703.
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© ARVO (1962-2015); The Authors (2016-present)
Medpor ® is an orbital implant for anophthalmic cavities made of high density porous polyethylene (HDPP), which is safe and has good biocompatibility. Omnipor ® is a new HDPP implant, with similar characteristics to Medpor®, which has not been studied in vivo. The purpose of this study was to compare the results obtained with Medpor® versus Omnipor® in an animal model in terms of vascularization of the device after two and four weeks of implantation. Vascularization is the main measurement for biocompatibility.
Sixteen New Zealand rabbits were randomized into four groups: Group 1: Medpor for 2 weeks, 2: Omnipor for 2 weeks, 3: Medpor for 4 weeks, 4: Omnipor for 4 weeks. All rabbits underwent enucleation of the right eye with implantation of a sphere of 12 mm of either Omnipor or Medpor according to the initial randomization. Two weeks after implantation, 8 rabbits (4 from each group) were sacrificed with sodium thiopental. Implants were extracted and fixated with 10% formaldehyde and parafin. The process was repeated at 4 weeks with the remaining rabbits.Three plaques (3 microns thick) were obtained at the equator of the implant which were stained with hematoxilin-eosin. The plaques were divided into quadrants and the deepest point of fibrovascular growth was measured from the external border in mm. This process was done by two independent pathologists obtaining 24 values for each rabbit. Other characteristics of the implant were reported such as: encapsulation, foreign body granulomatous reaction, infection, etc.
Fourteen rabbits were included in the final report (2 rabbits died soon after surgery). Seven in the Medpor group and 7 in the Omnipor group. The results are summarized in table 1. There were no complications related to the implants. Vascularization was significantly higher at week four compared to week two in both Medpor and Omnipor (p<0.0001). There was no statistical difference between the vascularization with Medpor vs. Omnipor at two and four weeks (p>0.05).
There was no difference in the degree of vascularization between the two implants. There were no complications related to the implants. None of the implants showed complete vascularization. More studies are needed to confirm the safety and biocompatibility of the new implant.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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