Bovine pericardium versus homologous sclera as a wrapping for hydroxyapatite orbital implants

PURPOSE: To report our experience with bovine pericardium as a wrapping material for hydroxyapatite orbital implants after enucleation and to compare the exposure rates of the implants wrapped with bovine pericardium versus donor sclera. METHODS: We retrospectively reviewed the records of all patients who received bovine pericardium-wrapped or donor sclera-wrapped hydroxyapatite implant after primary enucleation between March 1995 and December 2001. RESULTS: Of the 26 patients who received donor sclera-wrapped implants after enucleation, 1 (3.8%) had implant exposure. Of the 26 patients who received bovine pericardium-wrapped implants after enucleation, 6 (23%) had implant exposure. The incidence of implant exposure with the use bovine pericardium wrapping material was found to be significantly higher than with sclera (P = 0.05). Six of the 7 implant exposures were noted in the first 6 months after placement of the orbital implant. Five of the 6 exposed bovine pericardium-wrapped hydroxyapatite implants were associated with socket infection. The case of exposure of the sclera-wrapped implant was treated conservatively by observation. Six patients who had exposure of bovine pericardium-wrapped implants required multiple repairs because of recurrent exposures. Four of these patients eventually required removal of the implant. CONCLUSIONS: Despite the advantages of using bovine pericardium as a wrapping material for hydroxyapatite orbital implants, we observed a significantly higher incidence of exposure with bovine pericardium compared with donor sclera in the early postoperative period. Use of bovine pericardium as a wrapping material for orbital implants should be avoided unless some future modifications of the technique can be developed to prevent such complications.     

Fibrovascularization of porous polyethylene (Medpor) orbital implant in a rabbit model

PURPOSE: To evaluate the porous polyethylene (Medpor) orbital implant in a rabbit model and compare it with three other currently available porous implants: Bio-Eye coralline hydroxyapatite (HA), FCI(3) synthetic HA, and aluminum oxide (Bioceramic). METHODS: The porous polyethylene implant was examined macroscopically and microscopically (with scanning electron microscopy). Implantation was performed in 10 adult male New Zealand albino rabbits. Each animal underwent enucleation of the right globe under general halothane gas anesthesia, followed by placement of a 12-mm porous polyethylene implant. In 5 animals, the implant was encased in polyglactin 910 (Vicryl mesh); in the other 5, it was left unwrapped. The implants were moistened in saline before placement. Implant vascularization was evaluated by histopathology at 4, 8, 12, 16, and 24 weeks. RESULTS: The porous polyethylene implant was found to have a smoother exterior surface than the Bio-Eye, FCI(3) synthetic HA, and aluminum oxide implants. Rather than a uniform interconnected porous architecture, there was an extensive system of interconnected channels through the implant, ranging in size from 125 to 1000 microm. On high-power examination there was a more solid, woven appearance without any sign of the microcrystals seen in the other porous implants. One rabbit had a retrobulbar hemorrhage after surgery and was euthanized. All the other rabbits tolerated the implant well, and there were no complications. On histopathologic examination, fibrovascularization gradually increased over time. One implant was completely vascularized at 12 weeks, and both implants harvested at 16 weeks were completely vascularized. The implant harvested at 24 weeks showed only partial vascularization (14%). CONCLUSIONS: The porous polyethylene orbital implant represents an alternative implant for use after enucleation or evisceration or for secondary implantation. In our rabbit model, the porous polyethylene implant was well tolerated without complication. Complete fibrovascularization was first seen at 12 weeks. Porous polyethylene orbital implants appear to vascularize more slowly than Bio-Eye coralline HA, FCI(3) synthetic HA, and aluminum oxide implants.     

Current trends in managing the anophthalmic socket after primary enucleation and evisceration

PURPOSE: To evaluate current trends in the management of the anophthalmic socket after primary enucleation and evisceration. METHODS: The active membership of the American Society of Ophthalmic Plastic and Reconstructive Surgery (ASOPRS) was surveyed regarding primary enucleations and eviscerations performed between January and December 2002. Survey questions included practice demographics, orbital implant use, wrapping materials, placement of a motility peg, reasons for implant choice, and complications encountered. RESULTS: A total of 2,779 primary orbital implants were reported, comprising 1,919 (69.1%) enucleations and 860 (30.9%) eviscerations. The high-density porous polyethylene implant was used most frequently for enucleations (42.7%), followed by coralline hydroxyapatite (27.3%) and nonporous alloplastic implants (19.9%). For eviscerations, the high-density porous polyethylene implant was the most commonly used implant (42.3%), followed by hydroxyapatite (25.9%) and nonporous alloplastic implants (25.7%). The top 3 reasons for implant choice were outcome (69.3%), cost (43.6%), and experience (39.5%). Most implants were either not wrapped (59.8%) or were wrapped in donor sclera (25.2%) or polyglactin mesh (7.2%). Pegs were used in 8.1% of all implants reported. The most frequent complications encountered for unpegged implants were exposure (3.2%) and infection (0.4%). For pegged implants, the most common complications reported were pyogenic granuloma (13.7%), exposure (5.7%), and discharge (5.7%). CONCLUSIONS: In managing the anophthalmic socket, ASOPRS survey respondents preferred to use the porous polyethylene implant after primary enucleation and evisceration. Most orbital implants were not wrapped, and most surgeons preferred not to place a motility post or peg in the implant.     

Hydroxyapatite implant wrapping materials: analysis of fibrovascular ingrowth in an animal model

PURPOSE: To compare the influence of seven currently available spherical orbital implant wraps on host fibrovascularization of a hydroxyapatite (HA) orbital implant. METHODS: Five groups of 3 (15 total) adult male New Zealand albino rabbits underwent enucleation with placement of a 12-mm HA implant wrapped in high-porosity expanded polytetrafluoroethylene (e-PTFE), processed bovine pericardium, or processed human pericardium, sclera, or fascia lata. Magnetic resonance imaging before and after the intravenous administration of gadolinium-diethylenetriamine pentaacetic acid (DTPA, 0.1 mol/kg) was performed immediately before exenteration. Five rabbits (one with each of the different implant wraps) were killed at 4, 8, and 12 weeks, and the operated socket was exenterated. Histopathologic sections of the implants were then compared with the results of our previous study using polyglactin 910 mesh and autologous sclera as HA orbital implant wraps. RESULTS: Complete fibrovascularization of all the implants occurred by 12 weeks; however, HA implants wrapped with sclera, polyglactin mesh, and e-PTFE appeared to undergo more rapid fibrovascularization than spheres wrapped with other materials. CONCLUSIONS: Although all of the implant wraps studied may be suitable substitutes for donor sclera, we prefer polyglactin mesh because it is readily available, inexpensive, and without risk of transmissible diseases.     

Conjunctival melting syndrome associated with the use of bovine pericardium wrapping material

PURPOSE: To report 18 cases of unusually large, early conjunctival breakdown occurring with the use of bovine pericardium wrapping material for orbital implants. METHODS: Retrospective case series. The clinical course and histopathologic features of 18 cases of early conjunctival breakdown in patients who had undergone orbital implantation of bovine pericardium-wrapped hydroxyapatite or porous polyethylene are reviewed. RESULTS: Eighteen patients presented with unusually large (average 13.44 mm) conjunctival defects over bovine pericardium-wrapped implants. The average time from enucleation to exposure was approximately 4 months. Implants had to be removed in 8 of 18 cases. There was clinical and histologic evidence of tissue inflammation and conjunctival melting.CONCLUSIONS: The conjunctival melting phenomenon we report herein is alarming. We have abandoned the use of bovine pericardium as a wrapping material for implants after enucleation because of the unfavorable results.     

Exposure rates of wrapped and unwrapped orbital implants following enucleation.

PURPOSE: To compare the complication rate of porous polyethylene orbital motility implants with solid acrylic implants following enucleation and identify possible risk factors. METHODS: The authors retrospectively reviewed the charts of a total of 117 consecutive enucleations performed at the University of Illinois at Chicago between March 28, 1994, and May 28, 1999. Data obtained included patient demographics, surgical indication, implant type, attending surgeon, surgical technique, and any reported complications. The primary outcome was presence or absence of implant exposure at the final recorded visit. RESULTS: Of the 117 identified cases, 29 were eliminated due to insufficient follow-up data. Of the 88 remaining cases, 48 patients received porous implants and 40 received solid acrylic implants. Implant exposure developed in four cases. All exposures occurred in unwrapped porous polyethylene implants (n=2) or porous polyethylene implants wrapped in absorbable material (n=2). All exposures occurred in patients younger than 18 years of age, and 75% occurred early after trauma-associated enucleation surgery. CONCLUSIONS: The exposure rate of porous polyethylene implants in this study (9%) was found to be comparable to published rates for hydroxyapatite implants. There were no exposures of unwrapped solid acrylic spheres. Unwrapped porous implants in pediatric patients or following trauma-related enucleation may represent an increased risk for postoperative implant exposure. Absorbable wrapping of porous implants may carry the same risk for exposure as no wrapping. Porous implants wrapped in durable material appear to be as safe as solid acrylic spheres.     

2-Octyl cyanoacrylate tissue adhesive and muscle attachment to porous anophthalmic orbital implants

PURPOSE: To investigate the tolerance and efficacy of a topical bioadhesive for direct muscle attachment to porous orbital motility implants. METHODS: Ten New Zealand White rabbits underwent unilateral enucleation with unwrapped 12-mm spherical porous implants placed into the muscle cone. Four animals received porous polyethylene implants and 6 received bone-derived hydroxyapatite implants. Small amounts of a bioadhesive (2-octyl cyanoacrylate) were applied to the underside of the muscles. Muscles were placed onto the desired location of the implant with pressure for 15 seconds. The conjunctiva was closed with a 6-0 plain gut suture, and the animals were observed for 6 weeks. At 6 weeks, animals were killed and the surgical orbit was exenterated. Orbits and implants were processed for histologic analysis. In addition, tensile strength testing of muscle-implant attachments was performed and compared with various other types of muscle-implant or muscle-sclera attachments. RESULTS: All cases resulted in integration of the muscles without slippage. All unwrapped hydroxyapatite implants (n = 6/6) had small anterior implant exposures without infection, significant inflammation, or exposure. No exposures were noted in porous polyethylene implants (n = 0/4). All implants were filled with fibrovascular tissue by 6 weeks. 2-Octyl cyanoacrylate yielded tensile strengths similar to that of sutured muscle coupling. Conclusions: 2-Octyl cyanoacrylate is well tolerated in the orbit, inducing minimal inflammation. It effectively attaches muscles to porous implants without hindering permanent integration or vascularization. The exposure rate for unwrapped hydroxyapatite spheres was not caused by the adhesive, as evidenced by the lack of exposures in the porous polyethylene implant group. 2-Octyl cyanoacrylate may be effective in reducing the cost and time for enucleation surgeries when porous motility implants are used.     

Bovine pericardium as a wrapping for orbital implants

PURPOSE: We report the use of bovine pericardium as an alternative wrapping for porous orbital implants after enucleation. METHODS: We retrospectively reviewed the records of all patients who received a bovine pericardium-wrapped orbital implant after enucleation by the authors between August 1, 1996, and December 1, 1999. RESULTS: Eighty patients underwent placement of bovine pericardium-wrapped orbital implants. The average age at the time of implantation was 49.3 years (range, 5 years to 83 years). The mean follow-up interval was 11.8 months (range, 2 to 41 months). There were no intraoperative complications. No patient had secondary systemic infection or showed evidence of rejection. There was no clinical evidence to suggest that vascularization of the porous implant was unusually delayed, and there were no complications after secondary drilling and placement of a coupling post. Four (5%) of 80 patients had complications requiring removal of the spherical implant. All 4 patients had hydroxyapatite implants. Two patients had significant exposure requiring removal of the implant at 2 months after surgery; 1 patient had a chronic fistulous tract with secondary infection 3 years after surgery: and 1 patient had chronic orbital pain requiring removal of the implant at 1 year after surgery. CONCLUSIONS: The incidence of implant exposure was less than 4%. This compares favorably to the incidence of exposure of 9% to 21% reported in recent literature. Other complications were few and of minimal clinical significance. The authors conclude that bovine pericardium is a viable option to sclera as a wrapping for porous orbital implants.     

The use of vicryl mesh in 200 porous orbital implants: a technique with few exposures

PURPOSE: To report the results of a wrapping technique for porous orbital implants by using polyglactin 910 (Vicryl) mesh (Ethicon Inc., Somerville, NJ, U.S.A.). METHODS: We retrospectively reviewed the records of 200 consecutive patients from one author's practice who received a polyglactin 910 mesh-wrapped porous orbital implant after enucleation or as a secondary implant between October 1, 1996, and April 15, 2001. We recorded potential problems that might be attributed to polyglactin 910 mesh both before pegging (excessive inflammatory response to the material, conjunctival thinning, and implant exposure) and after pegging (exposure of the implant around the sleeve, conjunctival thinning, and implant exposure other than adjacent to the peg). RESULTS: One hundred twenty-two men and 78 women underwent placement of a polyglactin 910 mesh-wrapped porous orbital implant. The average age at the time of implantation was 48.9 years (range, 11 to 85 years). The average follow-up interval in the 200 patients was 19.4 months (range, 2 to 80 months). Thirteen of the 200 patients had less than 6 months of follow-up, leaving 187 patients with an average follow-up of 20.5 months (range, 6 to 80 months). There were 76 primary enucleations and 124 secondary orbital implants. Thirty-seven patients received a Bio-Eye hydroxyapatite implant (HA) (Integrated Orbital Implants, San Diego, Calif), 97 received a synthetic FCI hydroxyapatite implant (FCI, Issy-Les-Moulineaux, France), and 66 received a Bioceramic implant (aluminum oxide-Al2O3) (FCI, Issy-Les-Moulineaux, France). One hundred fourteen patients (57%) underwent peg placement. The average time to pegging was 9.9 months (range, 6 to 16 months). Before pegging, 4 of 187 patients (2.1%) had implant exposure. Three of these exposures followed secondary orbital implant placement (2 Bio-Eye HA, 1 synthetic FCI3 HA) and one followed an enucleation (synthetic FCI3 HA). Two patients required a temporalis fascia graft and one required a scleral patch; the remaining defect closed spontaneously. One patient had conjunctival thinning 6 months after orbital implantation, which remained stable with no frank exposure for 36 months. No patient had excess socket inflammation. After peg placement, 3 additional patients had exposure of the implant around the peg site. There were no cases of conjunctival thinning or exposure of the implant other than adjacent to the peg site. CONCLUSIONS: Polyglactin 910 mesh is an excellent option as a wrapping material for porous orbital implants. It is simple to use, readily available, eliminates the need for donor tissue, does not require a second operative site, and it is less expensive than other currently available wrapping materials. We attribute our high success rate to our technique, which emphasizes proper placement of the implant within the Tenon space, suturing the extraocular muscles anterior to their normal anatomic sites, and meticulous closure of the Tenon capsule and conjunctiva in separate layers.     

UK national survey of enucleation, evisceration and orbital implant trends

AIM: To evaluate current clinical practice in the UK in the management of the anophthalmic socket; choice of enucleation, evisceration, type of orbital implant, wrap, motility pegging and complications. METHODS: All consultant ophthalmologists in the UK were surveyed by postal questionnaire. Questions included their practice subspecialty and number of enucleations and eviscerations performed in 2003. Specific questions addressed choice of implant, wrap, motility pegging and complications. RESULTS: 456/896 (51%) consultants responded, of which 162 (35%) had a specific interest in oculoplastics, lacrimal, orbits or oncology. Only 243/456 (53%) did enucleations or eviscerations. 92% inserted an orbital implant after primary enucleation, 69% after non-endophthalmitis evisceration, whereas only 43% did so after evisceration for endophthalmitis (50% as a delayed procedure). 55% used porous orbital implants (porous polyethylene, hydroxyapatite or alumina) as their first choice and 42% used acrylic. Most implants inserted were spherical, sized 18-20 mm in diameter. 57% wrapped the implant after enucleation, using salvaged autogenous sclera (20%), donor sclera (28%) and synthetic Vicryl or Mersilene mesh (42%). A minority (7%) placed motility pegs in selected cases, usually as a secondary procedure. 14% of respondents reported implant exposure for each type of procedure and extrusion was reported by 4% after enucleation and 3% after evisceration. CONCLUSIONS: This survey highlights contemporary anophthalmic socket practice in the UK. Most surgeons use porous orbital implants with a synthetic wrap after enucleation and only few perform motility pegging.     

Orbital implants in enucleation surgery: a report by the American Academy of Ophthalmology

OBJECTIVE: To compare prosthetic and implant motility and the incidence of complications associated with porous and nonporous enucleation implants. METHODS: Literature searches conducted in January 2002 for 1985 to 2001 and May 2002 for October 2001 to 2002 retrieved relevant citations. The searches were conducted in MEDLINE and limited to articles published in English with abstracts. Panel members reviewed the articles for relevance to the assessment questions, and those considered relevant were rated according to the strength of the evidence. RESULTS: A randomized clinical trial and a longitudinal cohort study detected no difference in implant or prosthetic movement between nonpegged hydroxyapatite porous and spherical alloplastic nonporous implants. No controlled studies were retrieved that investigated whether pegging porous implants improves prosthetic movement. Several case series indicate that patients with pegged hydroxyapatite implants have some degree of improved prosthetic motility. Longitudinal cohort studies show that sclera-covered hydroxyapatite implants have higher exposure rates than sclera-covered silicone implants, and unwrapped porous polyethylene implants have higher exposure rates than unwrapped acrylic implants. There are numerous case series that document a wide range of implant exposure rates in patients with various enucleation implants. It is difficult to compare complication rates among implant types because patient populations vary, surgical techniques differ, and follow-up periods are often limited. CONCLUSIONS: Based on one randomized clinical trial, spherical alloplastic nonporous and nonpegged porous enucleation implants provide similar implant and prosthetic motility when they are implanted using similar surgical techniques. Coupling the prosthesis to a porous implant with a motility peg or post appears to improve prosthetic motility, but there are few available data in the literature that document the degree of the improvement. There is a widely variable incidence of porous implant exposure, but certain surgical techniques and the type of wrapping material seem to reduce the exposure rate. Additional research is needed to document the long-term incidence of complications related to porous enucleation implants and associated surgical techniques. This includes the use of wrapping materials and what procedural modifications, both surgical and prosthetic, are most effective in reducing these complications.     

Bovine pericardium (Tutopatch) wrap for hydroxyapatite implants

PURPOSE: To evaluate bovine pericardium (Tutopatch) as a wrapping material for hydroxyapatite implants in patients undergoing enucleation for uveal melanoma. METHOD: Prospective cohort study of patients who had enucleation for uveal melanoma between January 2003 and August 2003 were included in the study. Any patient with less than 3 months follow-up was excluded. Enucleation was performed under general anaesthesia followed by insertion of hydroxyapatite implants wrapped in bovine pericardium (Tutopatch). The recti muscles were sutured directly to the wrap. The tenon's capsule and conjunctiva were closed in two layers. A conformer was inserted at 1 week and artificial eye at 2-3 months. The patients were followed up regularly and were assessed for cosmetic result, exposure of implant, and the need for any further surgical procedures. RESULTS: A total of 19 patients (seven male and 12 female) were included in the study. Median age at diagnosis was 63 years (range 38-80 years). Median follow-up was 26 months (range 22-30 months). No patient developed postoperative complications of wound dehiscence. The overall cosmetic result was excellent in all the patients. The rate of postoperative complications compared favourably with published data using other wrapping materials/implants. CONCLUSION: Tutopatch is a safe wrapping material for hydroxyapatite orbital implants in patients undergoing enucleation for uveal melanoma.     

Enucleation, evisceration, and exenteration

This review outlines many of the recent advancements in the understanding and management of the anophthalmic patient. A population-based study demonstrated that the annual incidence of enucleations for all causes was about 3 to 5 per 100,000. Application of expandable orbital implants appears to be promising in the management of microphthalmia or anophthalmia in infants to maximize orbital growth. Some reports on the use of hydroxyapatite enucleation implants are encouraging, with no major complications observed in one large series. Yet other reports of hydroxyapatite implant exposures, at a very concerning frequency, are also beginning to emerge. Few of the exposures heal spontaneously; however, infections or extrusions are very rare, and they are attributable to the porous composition of the implant. Conjunctival flaps alone are suboptimal in the management of exposures. Adjunctive autologous fascial grafts seem preferable to heterologous sclera in the management of these exposures. Magnetic resonance imaging of the hydroxyapatite implant appears to be superior to bone scan in the noninvasive assessment of vascularization of these implants. Further advancements are necessary to achieve a more optimal enucleation implant.     

Porous orbital implants, wraps, and PEG placement in the pediatric population after enucleation

PURPOSE: To investigate complications of various porous orbital implants and wrapping materials in the pediatric population after enucleation. DESIGN: A retrospective, comparative, nonrandomized study. METHODS: Between November 1992 and November 2006, patients younger than 15 years old were collected for study participation. They underwent enucleation with porous orbital implants primarily or secondarily at National Taiwan University Hospital. The authors used the hydroxyapatite (HA), Medpor, and Bioceramic orbital implant. The HA implant was wrapped with four different materials: donor sclera, Lyodura, porcine sclera, and Vicryl mesh. A part of HA implants and all bioceramic implants were wrapped with Vicryl mesh, added anteriorly with scleral patch grafts. All Medpor implants were unwrapped. RESULTS: Forty-seven cases had more than a two-year follow-up. The exposure rates according to implants and wraps were: donor sclera-wrapped HA (two of nine, 22%), porcine sclera-wrapped HA (three of three, 100%), Vicryl mesh-wrapped HA (one of five, 20%), and unwrapped Medpor (one of four, 25%). No exposure was found in four Lyodura-wrapped HA implants, and 22 Vicryl mesh-wrapped HA and Bioceramic implants with anteriorly scleral coating. The exposure rate was lower in cases with implants wrapped by our method and Lyodura than in those with implants wrapped by other materials (P < .001). Of 47 patients, 20 (42.5%) were fitted with peg-coupled prostheses and all had good prosthetic movements subjectively. CONCLUSIONS: Different types of implants and wraps resulted in various exposure rates in the pediatric population. The modified wrapping technique may prevent porous implants from exposure in children.     

Fibrovascular ingrowth in porous ocular implants: the effect of material composition, porosity, growth factors, and coatings.

PURPOSE: Fibrovascular ingrowth into various porous ocular implants as a function of implant material composition, porosity, growth factors, and coatings was investigated in a pilot study in an animal model. METHODS: Eighty-one New Zealand white rabbits underwent unilateral enucleation and implantation with ocular implants composed of the following materials: coralline hydroxyapatite (HA) with 200-microm pores (HA200) or 500-microm pores (HA500), synthetic HA (synHA), and high-density porous polyethylene (PP). The HA200, HA500, and PP implants were implanted untreated or after treatment with recombinant human basic fibroblast growth factor (Rh-bFGF). Nine HA500 implants were implanted after coating with calcium sulfate (plaster of Paris) to provide a smooth outer surface. Implants were harvested at 1-, 2-, 4-, or 8-week intervals and were examined histologically. RESULTS: A significant difference was found between untreated HA500 and PP, with PP showing better ingrowth. There was no significant difference between untreated HA and PP, nor between untreated HA500 and synHA. Significant increases in ingrowth were found in HA200 compared with HA500, and in Rh-bFGF-treated implants compared with untreated controls. The calcium sulfate-coated implants showed less vascularization compared with the uncoated implants, although the difference was not significant. CONCLUSIONS: Fibrovascular ingrowth occurred earlier in HA200 implants than in HA500 implants, and was enhanced when implants were treated with Rh-bFGF.     

Behavior of various orbital implants under axial compression

PURPOSE: To determine and compare the amount of force required to disrupt the integrity of various orbital implants. METHODS: Compression tests were carried out by using a servo-electrical universal testing system on orbital implants including aluminum oxide (Bioceramic implant, FCI, Issy-Les-Moulineaux, France), coralline hydroxyapatite (HA) (Bio-Eye, Integrated Orbital Implants, Inc., San Diego, CA, U.S.A.), bovine HA (Molteno M-Sphere, IOP Inc., Costa Mesa, CA, U.S.A.), synthetic HA (FCI3, FCI, Issy-Les-Moulineaux, France), Chinese HA (H + Y Comprehensive technologies, Philadelphia, PA, U.S.A.), polylactic acid (Kinsey Nash Corporation, Duluth, MN, U.S.A.), porous polyethylene (Medpor, Porex Surgical Inc., College Park, GA, U.S.A.), and polymethylmethacrylate. RESULTS: Two basic groups of implants were identified: those that eventually reach a critical compression point and collapse (coralline HA, aluminum oxide, synthetic FCI3 HA, bovine HA, Chinese HA, and polymethylmethacrylate), and those that do not collapse but gradually compress with increasing load (porous polyethylene, polylactic acid). For similar-sized implants, the critical collapse point was earliest for the FCI3 HA implant, followed by the coralline HA, aluminum oxide, and polymethylmethacrylate implants. Smaller-sized collapsible implants showed earlier critical collapse points than larger-sized implants of similar material. CONCLUSIONS: A technique was established to assess the force required to disrupt the integrity of various orbital implants that is reliable, unbiased, and repeatable with any orbital implant. Orbital implants of different materials and sizes demonstrate different degrees of integrity. It is important to use similar-sized implants when comparing the integrity of different implant materials because size influences the force required to overcome the structural integrity of the implant.     

Prevention of exposure of porous orbital implants following enucleation

PURPOSE: To investigate effectiveness of adding a scleral patch graft on a Vicryl mesh-wrapped porous orbital implant to prevent exposure following enucleation. DESIGN: A retrospective, comparative, nonrandomized study. METHODS: From October 1996 to February 2006, 74 consecutive patients (74 sockets) who received porous orbital implants primarily or secondarily after enucleation at National Taiwan University Hospital (72 cases) and at Far Eastern Memorial Hospital (2 cases) were collected. Patient demographics, ocular diagnosis, the surgical technique, prior ophthalmic surgery, type, covering, and size of the implant, follow-up periods, and complications associated with pegs and implants were recorded. Group 1 patients received a Vicryl mesh-wrapped implant without a scleral patch graft. Group 2 patients received anterior capping with a scleral patch on the Vicryl mesh-wrapped implant. RESULTS: Of 74 identified cases, 12 were excluded for insufficient follow-up. The 62 remaining cases had more than a two-year follow-up. There were two implant exposures (12%, two of 17) in group 1. Retroauricular myoperiosteal graft and scleral patch were used to repair exposed implants successfully. No exposure was noted in group 2 (n = 45). A significant between-group difference in exposure rate was found (P = .02). Early conjunctival dehiscence followed by spontaneous healing occurred in three group 2 patients. CONCLUSIONS: Scleral patch graft and Vicryl mesh can act as duplicate barriers between anterior surface of implants and overlying soft tissue. The modified wrapping technique prevents porous implants from exposure effectively.     

Primary placement of a titanium sleeve in hydroxyapatite orbital implants

BACKGROUND: To study a new surgical option of primary placement of a titanium sleeve into hydroxyapatite implants during enucleation or evisceration. METHODS: A standard enucleation or cornea preserved evisceration was performed, followed by preplacement of a titanium sleeve into the hydroxyapatite implant by a hand drill sleeve driver. Care must be taken to ensure that the titanium sleeve is positioned centrally when the implant is put inside the orbital socket or eviscerated shell. The Tenon capsule and conjunctiva were meticulously closed with minimal tension. Complications such as sleeve exposure, coralline exposure, and infection of the titanium sleeve were closely observed. RESULTS: In all, 30 patients were treated in the above fashion with 10 enucleation and 20 evisceration procedures. The follow-up period ranged from 9 to 24 months. Three of the sleeves were found to have exposed spontaneously at 5 and 7 weeks following original surgery. They had no further complication except one sleeve loosening. The remaining 27 sleeves that did not spontaneously expose pursued secondary exposure of the titanium sleeve and peg insertion by conjunctival cutdown procedure 3 months after original surgery. Two sleeves were found to be oblique positioned after the conjunctival cutdown procedure. Fortunately, all the 30 patients were successfully fit with a peg-coupled prosthesis with good motility. CONCLUSION: Primary placement of a titanium sleeve into hydroxyapatite implants has several advantages, including high patient acceptance, technical simplicity, and office-based conjunctival cutdown pegging procedure. By avoiding the expense of postoperative imaging study and additional prosthetic modification, a more rapid and efficient rehabilitation is possible.     

Use of bovine pericardium as a wrapping material for hydroxyapatite orbital implants

AIM: To present the results of 27 patients who had enucleation for malignant melanoma of the choroid with hydroxyapatite implant wrapped in bovine pericardium. METHOD: A retrospective study was performed on 27 patients, 12 males and 15 females, who had enucleation as a primary treatment for their choroidal melanomas. The patients were followed up at 1 week, 1 month, 3 months, and then every 6 months. A conformer was fitted at 1 week and an artificial eye at 1 month. The average follow up was 1.7 years. RESULTS: No patient had extrusion of the implant. One patient needed repair of the wound, two patients required a lateral tarsal strip, and one patient developed a conjunctival granuloma, which did not need excision. In one patient there was shallowing of the inferior fornix. The cosmetic results and ocular movement were satisfactory in all but one patient. CONCLUSION: Use of bovine pericardium as wrapping material for the hydroxyapatite implants has shown promising results with minimal extrusion rates providing an effective alternative for sclera, eliminating the potential risks of CJD.     

Experience with orbital implants in particular with porous hydroxyapatite materials

PURPOSE: Various materials have been developed since the first implantation of a hydroxyapatite sphere in 1985. They are similar to the porous basic structure and imitate the biological behavior of coralline implants. This article presents own clinical experience with hydroxyapatite implants from 1993 to 2003 and compares own results and other porous orbital implants in the international scientific literature. RESULTS: The original hydroxyapatite implant is well tolerated and implant extrusion is rare. A retrospective analysis of 357 patients regarding this complication shows an extrusion rate of 2.6% over 10 years. The subjective positive tolerance of 71.2% corresponds to the results of international studies. After several stages of development the synthetic product (FCI3) is now comparable with the original product with regard to operative complications and subjective compatibility. Both orbital implants should be used with a protective covering to avoid premature extrusion and to facilitate suturing the extraocular muscles anterior. When using material from humane donors the material must be guaranteed to be completely sterile. The use of vicryl as an orbital plomb wrapping leads to contradictory reports in the literature. Hydroxyapatite ceramics in combination with silicone india rubber represent an alternative to the materials listed above and in this case a wrapping of the orbital plomb is unnecessary. Spherical orbital implants made of aluminum oxide (bioceramic implant) are an alternative to corraline hydroxyapatite implants. Because of their porous,crystalline structure bioceramic implants vascularize well. Porous polythylene orbital implants,which are not available in Germany, are economical, but due to their porosity and vascularization properties they are not comparable with pure hydroxyapatite or hydroxyapatite ceramics. FUTURE VIEW: The dynamic development of the infant anopthalmus adapted to the size growth of the orbita and the exact volume replenishment of the adult orbita cannot yet be fulfilled with the presently available porous hydroxyapatite materials and is the subject of future research.