Bovine bone xenograft as orbital implants in rabbit eyes / 国际眼科杂志(Guoji Yanke Zazhi)

·AIM: To assess the biocompatibility of bovine bone as orbital implants in rabbits.·METHODS: Bovine bone graft was used as an ocular implant in rabbits to determine whether it could be successfully used in the anophthalmic socket as an alternative to the expensive synthetic alloplastics. Evisceration of eyes with and without bovine bone orbital implantation was performed in the right eyes of 12 New Zealand white rabbits.Group Y (n =6) was eviscerated without implant, meanwhile Group X (n =6) was eviscerated with insertion of an orbital implant using bovine bone. Observation was carried out on day 1, day 7, day 14, day 28 and day 42. Serial clinical examination was carried out based on a few fixed criteria,which included rate of infection, implant migration, evidence of wound breakdown and any restriction of intraocular movements. The implanted eyes were then enucleated on day 42. The enucleated eyes were sent for histopathological evaluation to record the type of inflammatory reaction and rate of fibrovascular ingrowth.·RESULTS: Serial clinical examination showed presence of minimal infection in all eyes, both in Group X implanted) and Group Y (control) on first postoperative day, which responded well with antibiotics. Infection occurred in the implanted group after first postoperative day, but there was no evidence of orbital migration or extrusion of implant, wound breakdown, restriction of extraocular movement, severe infection or any physical abnormality. Histopathological examination revealed good fibrovascular ingrowth in the implanted group, with minimal rejecting reaction of rabbit eye towards bovine bone implant.·CONCLUSION: This study shows that bovine orbital implant has a good biocompatibility in rabbit eyes and its cost is acceptable.

Effect of Basic Fibroblast Growth Factor on Fibrovascular Ingrowth into Porous Polyethylene Anophthalmic Socket Implants

To investigate the effect of basic Fibroblast Growth Factor (bFGF) on fibrovascular ingrowth into porous polyethylene orbital implants (Medpor (R) ) and to investigate any differences according to the method of administration. For the treated groups, after evisceration and Medpor (R) implantation, bFGF was administered by soaking Medpor (R) in the bFGF solution, and/or by injecting bFGF into the Medpor (R) 1 week after the operation. Implants were removed 4 weeks after the operation and examined for the degrees of fibrovascular ingrowth by light microscopy. The percentages of the cross-sectional area of the implant occupied by fibrovascular ingrowth and the numbers of proliferated vessels were significantly higher in the bFGF-treated groups (Mann Whitney test, p 0.05). bFGF promoted fibrovascular ingrowth into porous polyethylene orbital implants regardless of the route of administration. Therefore, bFGF might be helpful to prevent complications such as implant exposure.

The Effect of the Synthetic Bone Glass on the Fibrovascularization into Porous Polyethylene Orbital Implant

PURPOSE: To evaluate the effect of the synthetic bone glass particulate (BG) on the fibrovascular ingrowth into porous polyethylene orbital implant (PP). METHODS: Forty eight rabbits were divided into 4 groups according to the surgical techniques and implanted materials. One eye was enucleated one eye and PP was implanted in group 1, was eviscerated and PP was implanted in group 2, was enucleated and BG, containing 30% by weight synthetic bone glass particulate, was implanted in group 3, and was eviscerated and BG was implanted in group 4. All implants of each group were assessed by histologic study at the first, second, fourth, and eighth weeks postoperatively. The area of fibrovascular ingrowth was calculated by histologic examination. RESULTS: There were no statistically significant differences in the fibrovascular ingrowth among these groups. A greater number of vessels per unit area and matured fibrous tissue was found in the more outer zone at longer time after implantation, but there was not statistically significant difference among the four groups. CONCLUSIONS: On the basis of this study, the synthetic bone glass particulate did not significantly increase the rate of fibrovascular ingrowth into porous polyethylene orbital implant in rabbits.

The effect of polyethylene orbital implant(Medpor(R)) pretreated with autogenous fibrovascular tissues in rabbits

PURPOSE: The purpose of this study is to determine whether partially neovascularized Medpor(R) by preplacement of implant to buttock area for one month before secondary orbital insertion demonstrates earlier refibrovascular ingrowth into implant than that in primary orbital placement. METHODS: Thirty-five rabbits were divided into two groups: Group A (15 rabbits) ; primary orbital implantation of Medpor(R)(nonvascularized) after enucleation, Group B (15 rabbits) ; secondary orbital implantation of implant (vascularized) after enucleation after harvesting implants from buttock area, inserted for one month prior to orbital implantation. Five neovascularized implants by preplacement of implant to buttock area for one month were sectioned and investigated for the fibrovascular ingrowth, expression of bFGF, and CD-31 to evaluate the influence of pretreatment. Implants from group A and B were harvested from the orbit at 1, 2, 4, 6, and 8 weeks postoperatively. The implants were sectioned and studied grossly and histopathologically. Immunohistochemical study on bFGF and CD-31 were conducted to detect the angiogenetic factor and degree of angiogenesis in both group A and B. RESULTS: The fibrovascular ingrowth and expression of bFGF and degree of angiogenesis in group B were higher than those in group A. The degrees of angiogenesis were well correlated with bFGF expression. CONCLUSIONS: This animal model may provide the basis for the future investigation of agents and structural modifications directed towards optimization of fibrovascular ingrowth into porous anophthalmic socket implants and clinically apply to enucleation for the vascular compromised patients such as in the settings of postirradiation, diabetes.

Study on Fibrovascular Ingrowth into the Intraocular Implant, Medpor(R)

PURPOSE: We investigated the effects of bFGF/Sucralfate/Hydron suspension and hyperbaric oxygen on fibrovascular ingrowth into porous implants materials. METHODS: Eight rabbits underwent bilateral abdominal incision through which porous orbital disc-shaped implants were inserted between abdominal muscles. These implants were either uncoated or coated with suspension of bFGF/Sucralfate/Hydron. Hyperbaric oxygen therapy was performed on 4 selected rabbits for 5 days or 10 days. Implants were harvested after 3 days, 1 week, 2 weeks and 4 weeks. RESULTS: Enhanced fibrovascular ingrowth was shown in bFGF/Sucralfate/Hydron or hyperbaric oxygen treated implants. bFGF/Sucralfate/Hydron treated implants demonstrated more fibrovascularization than hyperbaric oxygen treated implants. CONCLUSIONS: Simultaneous therapy of bFGF/Sucralfate/Hydron and hyperbaric oxygen showed more fibrovascularization than separately treated implants.

MRI Findings of Fibrovascularization in Hydroxyapatite Orbital Implants

To evaluate the degree of fibrovascular ingrowth in hydroxyapatite orbital implant, we performed gadolinium-enhanced T1 weighted magnetic resonance imaging in 10 eyes elapsed 6 months after hydrovyapatite implantation and on 6 eyes at 1, 2, 3, 4, and 6 months after hydroxyapatite implantation, and calcualted the volume of enhanced area. In 10 eyes elapsed 6months after hydroxyapatite implantation, all showed enhancement over 90%(average, 93.6%). In 6 eyes examined at 1, 2, 3, 4, and 6 months after hydroxyapatite implantation, the average percentage of enhanced area was 73.2% at 1 month, 76.0% at 2 months, 80.0% at 3 months, 89.8% at 4 months, and 92.0% at 6 months. the enhanced volume was over 90% at 4 months after the implantation in almost all cases. In hydroxyapatite orbital implantation done by our modified procedures, we suggest that the drilling for peg placement is possible 4 months after the implantation.

Fibrovascular Ingrowth of the Orbital Hydroxyapatite Implant evaluated by Magnetic Resonance Imaging

The degree and completion of the fibrovascular ingrowth into the implant were evaluated by magnetic resonance imaging on twenty-one cases of intraorbital hydroxyapatite implant insertion following evisceration (16 cases), enucleation (3 cases), and secondary implantation (2 cases) operated at the Department of Ophthalmology, Yeungnam University Hospital during the period from April 1993 through June 1995. Six to seven microholes were made into the hydroxyapatite sphere. It was inserted into the orbital cavity without wrapping with the preserved sclera during the enucleation procedure and posterior scleral incision was performed for insertion of the implant in the evisceration procedure. The magnetic resonance imaging was first taken 2 months postoperatively and then a month interval by the time of complete fibrovascularization. The range of complete fibrovascularization time varied from 86 to 203 postoperative days. The mean time was 4.48 months which was significantly faster than that of the other authors reported in the literatures. The complete fibrovascularization time of the implant had no significant relation to the preoperative conditions, the age, the surgical procedures and the sizes of the implant.