Auricular cartilage versus donor sclera as a wrapping of hydroxyapatite orbital implants

AIM: To retrospectively compare postoperative outcomes after primary enucleation and placement of a hydroxyapatite(HA) implant without wrapping, wrapped with auricular cartilage or donor sclera. METHODS: Medical records of patients presented as intraocular tumor or severe ocular injury were identified from the electronic medical record system. Cases underwent enucleation and HA orbital implantation were enrolled in this study and were divided into 3 groups according to the wrapping material of HA implant. Cases with autogenous cartilage caps were enrolled in group A(n=11), with donor sclera caps in group B(n=12), and without any wrapping material in group C(n=9). Follow-ups were set at 1, 2 wk, 1, 3, 6, and 12 mo after surgery.RESULTS: Altogether 32 cases finished the followup and were enrolled in this study. Three cases(27.27%) in group A, 4 cases(33.33%) in group B, and 4 cases(44.44%) in group C developed one complication each after surgery. In group A, no HA exposure occurred, but conjunctival inclusion cyst occurred in one and severe conjunctive chemosis in two cases. In group B, one HA exposure occurred, conjunctive inclusion cysts occurred in one, severe conjunctive chemosis occurred in one, and conjunctival granuloma occurred in one case. In group C, one HA exposure occurred, severe conjunctive chemosis occurred in two cases, and conjunctival granuloma occurred in one case. The case of exposure of none-wrapped implant was noted in the first 6 mo after placement of the orbital implant. The case of exposure of donor sclerawrapped implant was noted at the 12 mo after placement of the orbital implant. Both exposure cases were treated successfully with conservative treatment.CONCLUSION: With low incidence of implant exposure and mild complications, auricular cartilage can be a good choice of alternative wrapping material of orbit implant with satisfied outcome.

Effects of Vascular Endothelial Cell Growth Factor on Fibrovascular Ingrowth into Rabbit's Hydroxyapatite Orbital Implant

Summary: The effects of different concentrations of vascular endothelial cell growth factor (VEGF) on the fibrovascular ingrowth into rabbits hydroxyapatite orbital implant were investigated. Twelve New Zealand white rabbits were divided into 3 groups and received hydroxyapatite orbital implant surgery in their right eyes. Before and after the operation, the implants were treated with 10 ng/ml VEGF, 100 ng/ml VEGF, or normal saline as control group. The animals received technetium bones scan at 2, 4, and 6 weeks postoperatively. The mean radioactivity counts within region of interest (ROI) of the surgery eye (R) and the non-surgery eye (L) in the same animal were tested, and the R/L ratios were calculated. The implants were harvested at 6th weeks and examined histopathologically. The results showed that at second week, there was no significant difference in mean R/L ratios between VEGF group and control group (F=2.83, P=0.111); At 4th week (F=7.728, P=0.011) and 6th week (F=7.831, P=0.011) postoperatively, the mean ratios in VEGF groups were significantly higher than that in control group. At 6th week postoperatively, the fibrovascularization rates in VEGF groups were higher than in control group significantly (F=8.711, P=0.008). It was suggested that VEGF could promote the fibrovascular ingrowth into hydroxyapatite orbital implant, thus might shorten the time required for complete vascularization of the HA orbital implant.

Treatment of intractable orbital implant exposure with a large conjunctival defect by secondary insertion of the implant after preceding dermis fat graft

AIM: To report a procedure and results of a two-stage operation to manage intractable extensive orbital implant exposure with a large conjunctival defect which was difficult to treat with dermis fat grafts due to repeated graft necrosis. METHODS: A retrospective chart review of four patients who had extensive orbital implant exposures with large conjunctival defects and had past histories of repeated autologous or preserved dermis graft failures was done. As a first-stage operation, the problematic pre-existing orbital implants were removed and autologous dermis fat grafts alone were performed on the defect area. Four months later, new orbital implants were secondarily inserted after confirmation of graft survival. The size of the conjunctival defects and state of the extraocular muscles were checked preoperatively. Success of the operations and complications were investigated.RESULTS: The mean size of the conjuctival defects was 17.3mm×16.0mm, and the mean time from the initial diagnosis of orbital implant exposure to implant removal and autologous dermis fat graft was 20.8 months. After implant removal and autologous dermis fat graft, no graft necrosis was observed in any patients. Also, implant exposure or fornix shortening was not observed in any patients after new orbital implant insertion. CONCLUSION: The secondary insertion of a new orbital implant after pre-existing implant removal and preceding dermis fat graft is thought to be an another selective management of intractable orbital implant exposure in which dermis fat grafts persistently fail.

Comparative study of modified and conventional secondary hydroxyapatite orbital implantations

AIMTo compare the clinical effects of the modified and conventional secondary hydroxyapatite orbital implantations.

In vitro adherence of conjunctival bacteria to different oculoplastic materials

AIM: To investigate the resistance to bacterial adhesion of materials used in oculoplastic surgery, particularly materials used in the manufacture of orbital implants.METHODS: Seven organisms of conjunctival flora(two strains of Staphylococcus epidermidis and one strain each of Staphylococcus aureus, Staphylococcus hominis, Corynebacterium amycolatum, Acinetobacter calcoaceticus, and Serratia marcescens) were selected. A lactic acid bacterium(Lactobacillus rhamnosus) was also included as positive control because of its well-known adhesion ability. Eight materials used to make oculoplastic prostheses were selected(glass, steel, polytetrafluoroethylene, polymethylmethacrylate, silicone from orbital implants, commercial silicone, porous polyethylene, and semismooth polyethylene). Materials surfaces and biofilms developed by strains were observed by scanning electron microscopy. Kinetics of growth and adhesion of bacterial strains were determined by spectrophotometry. Each strain was incubated in contact with plates of the different materials. After growth, attached bacteria were re-suspended and colony-forming units(CFUs) were counted. The number of CFUs per square millimetre of material was statistically analyzed.RESULTS: A mature biofilm was observed in studied strains except Staphylococcus hominis, which simply produced a microcolony. Materials showed a smooth surface on the microbial scale, although steel exhibited 1.0-μm-diameter grooves. Most organisms showed significant differences in adhesion according to the material. There were also significant differences in thetotal number of CFUs per square millimetre from each material(P=0.044). CFU counts were significantly higher in porous polyethylene than in silicone from orbital implants(P=0.038).CONCLUSION: Silicone orbital implants can resist microbial colonization better than porous polyethylene implants.

Next-generation finely controlled graded porous antibacterial bioceramics for high-efficiency vascularization in orbital reconstruction

Eyeball loss due to severe ocular trauma,intraocular malignancy or infection often requires surgical treatment called orbital implant reconstruction to rehabilitate the orbital volume and restore the aesthetic appearance.However,it remains a challenge to minimize the postoperative exposure and infection complications due to the inert nature of conventional orbital implants.Herein,we developed a novel Ca-Zn-silicate bioceramic implant with multi-functions to achieve the expected outcomes.The porous hardystonite(Ca2ZnSi2O7)scaffolds with triply periodic minimal surfaces(TPMS)-based pore architecture and graded pore size distribution from center to periphery(from 500 to 800μm or vice versa)were fabricated through the digital light processing(DLP)technique,and the scaffolds with homogeneous pores(500 or 800μm)were fabricated as control.The graded porous scaffolds exhibited a controlled bio-dissolving behavior and intermediate mechanical strength in comparison with the homogeneous counterparts,although all of porous implants presented significant antibacterial potential against S.aureus and E.coli.Meanwhile,the pore size-increasing scaffolds indicated more substantial cell adhesion,cell viability and angiogenesis-related gene expression in vitro.Furthermore,the gradually increasing pore feature exhibited a stronger blood vessel infiltrating potential in the dorsal muscle embedding model,and the spherical implants with such pore structure could achieve complete vascularization within 4 weeks in the eyeball enucleation rabbit models.Overall,our results suggested that the novel antibacterial hardystonite bioceramic with graded pore design has excellent potential as a next-generation orbital implant,and the pore topological features offer an opportunity for the improvement of biological performances in orbital reconstruction.