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M.J. Richard, J. White, J.D. Wright, J.J. Dutton; Fibrovascularization of Epor Porous Polyethylene Orbital Implant in a Rabbit Model . Invest. Ophthalmol. Vis. Sci. 2005;46(13):4225.
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Purpose: To evaluate the tolerability and the rate of soft tissue vascularization of the Epor porous polyethylene orbital implant in a rabbit model and to compare it to other published reports for soft tissue vascularization of orbital implants. Methods:Each of 12 rabbits was randomized to one of three groups (4 rabbits per group). Once randomized, each rabbit underwent surgical enucleation of the right globe with implantation of a 15mm Epor porous polyethylene implant. The implants were harvested and examined by histopathology at weeks 1 (group 1), 2 (group 2), and 3 (group 3). The implants were fixed in 10% formalin and embedded in paraffin; two 3µm sections were then cut at the equator of each implant and stained with hematoxylin and eosin. A template marked to show 3mm increments was placed over each specimen to grade the deepest area of penetration of fibrovascular ingrowth and the specimen was then given a score of 1–5 (1= 0–3mm of ingrowth, 2= 3–6 mm, 3= 6–9mm, 4= 9–12mm, 5= 12–15mm). The 2 specimens for each implant were graded in a blinded fashion by 2 separate observers and the 4 scores averaged. Each averaged score (of 1 to 5) was converted to a percentage of fibrovascular ingrowth with 1 equal to 20%, 2 equal to 40%, up to 5 (100%). Results: One rabbit died intraoperatively of a pulmonary embolus. All other rabbits tolerated the implant well without complication. The average score for group 3 (implants harvested at 3 weeks) was 90.00% with a SD of 9.13%. Group 2 (implants harvested at 2 weeks) averaged 76.67% +/– 12.58% of fibrovascular ingrowth and group 1 (implants harvested at 1 week) averaged 35.00% +/– 15.81% ingrowth. The amount of vascularization noted in group 3 was statistically significant vs. group 1 (p=0.00426, 1–tailed student t test). Likewise group 2 reached statistical significance vs. group 1 (p=0.00675). Group 3 did not reach statistical significance when compared to group 2 (p=0.0809). Conclusions: The Epor porous polyethylene implant was well tolerated in a rabbit model. Fibrovascularization occured in a stepwise fashion with increasing amounts of soft tissue ingrowth seen in implants as they were left in the orbit longer. Fibrovascularization occured at a rate equal to or quicker than what has been reported in other series.
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