Biomaterials for orbital implants and ocular prostheses: overview and future prospects

Encapsulated cell technology: Delivering cytokines to treat posterior ocular diseases

Encapsulated cell technology (ECT) is a targeted delivery method that uses the genetically engineered cells in semipermeable polymer capsules to deliver cytokines. Thus far, ECT has been extensively utilized in pharmacologic research, and shows enormous potentials in the treatment of posterior segment diseases. Due to the biological barriers within the eyeball, it is difficult to attain effective therapeutic concentration in the posterior segment through topical administration of drug molecules. Encouragingly, therapeutic cytokines provided by ECT can cross these biological barriers and achieve sustained release at the desired location. The encapsulation system uses permeable materials that allow growth factors and cytokines to diffuse efficiently into retinal tissue. Moreover, the ECT based treatment can be terminated timely when we need to retrieve the implant, which makes the therapy reversible and provides a safer alternative for intraocular gene therapy. Meanwhile, we also place special emphasis on optimizing encapsulation materials and enhancing preservation techniques to achieve the stable release of growth factors and cytokines in the eyeball. This technology holds great promise for the treatment of patients with dry AMD, RP, glaucoma and MacTel. These findings would enrich our understandings of ECT and promote its future applications in treatment of degenerative retinopathy. This review comprises articles evaluating the exactness of artificial intelligence-based formulas published from 2000 to March 2024. The papers were identified by a literature search of various databases (PubMed/MEDLINE, Google Scholar, Cochrane Library and Web of Science).

Anophthalmic socket in retinoblastoma: Exploring complications and risk factors in a tertiary centre in Malaysia

PURPOSE

To evaluate the complications of anophthalmic socket in retinoblastoma patients at a tertiary centre in Malaysia.

DESIGN

Retrospective study.

METHODS

Patients who underwent enucleation for retinoblastoma were reviewed from 2004-2020. Details were recorded, including demographics, diagnosis, surgical techniques, implant types, additional therapies, and complications.

RESULTS

Of 250 patients with retinoblastoma managed over the period, the anophthalmic sockets of 160 eyes who underwent enucleation were analysed. The mean age at enucleation was 2.03 years (26 days to 9.18 years). The follow-up periods after enucleation range from 5 days to 16.83 years. Porous polyethylene (Medpor) implants were used in 135 patients (84.4%), as were Bioceramic in 9, glass balls in 7, acrylic in 7, dermis fat grafts in 1, and silicone implants (Aurosphere) in 1. The overall complications in our study were 28.8%. Complications seen in the study included implant exposure (12.5%), shallow inferior fornix (10.6%), granuloma formation (3.1%), discharge (2.5%), implant migration (1.9%), ptosis (0.6%), and orbital dystopia (0.6%). Implant exposure is solely found in Medpor, more common in those with donor sclera caps, and exposure times range from 28 days to 11.42 years. The suturing of the Tenon and conjunctiva in separate layers significantly reduced the rate of implant exposure. Six out of seven radiation patients had shallow inferior fornixes.

CONCLUSIONS

Long-term post-enucleation complications were not uncommon. Luckily, most had good outcomes, with a few needing surgical intervention. Meticulous suturing technique on the Tenon and conjunctival layer is essential to prevent implant exposure.

Management of external ocular prosthesis by ocularists: results of an online survey conducted in Brazil and Spain

PURPOSE

To analyse the ocularist's perspective on the management of the anophthalmic socket and external ocular prosthesis (EOP).

METHODS

Ocularists from two countries were invited to participate in an online questionnaire. Data were collected on demographics, anophthalmic socket and EOP management (manufacturing, use, cleaning), complications, follow-up visits and multidisciplinary care. The frequency and proportions of the responses were statistically analysed.

RESULTS

The questionnaire was addressed to 20 Brazilian and 17 Spanish ocularists, obtaining a response rate of 65% and 64.7%, respectively. 62.5% of respondents were men. The most common cause of anophthalmia in Brazil (69.2%) and Spain (36.4%) is an eye disease (chi square: p = 0.188). Polymethylmethacrylate (PMMA) is the most commonly used material in EOP manufacture (chi square: p = 0.448), and 70.8% reported using customized EOPs (chi square: p = 0.069). Deposits are frequently observed in both countries (chi square: p = 0.157). Changing the prosthesis is recommended after 5 to 10 years by Brazilian ocularists, and after less than 5 years of use by Spanish ocularists (81.8%) (chi square: p = 0.041). Annual follow-up is recommended by Spanish ocularists (45.5%), while semestral (38.5%) and case-dependent (38.5%) follow-up is recommended by Brazilian ocularists (chi square: p = 0.267). Daily cleaning is advocated by 61.5% of Brazilian ocularists and once a month by 45.5% of Spanish ocularists (chi square: p = 0.098), with 75% of ocularists from both countries not recommending EOP removal at night (Fisher´s exact test: p = 0.166). Good communication between ocularists and ophthalmologists was reported by 87.5% of our responders (chi square: p = 0.642).

CONCLUSION

Although there are no unified protocols on the management of EOPs, Brazilian and Spanish ocularists follow similar guidelines. Differences between countries were the patients´ referral and the prosthesis´ useful life.

Smart Contact Lenses-A Step towards Non-Invasive Continuous Eye Health Monitoring

According to the age-old adage, while eyes are often considered the gateway to the soul, they might also provide insights into a more pragmatic aspect of our health: blood sugar levels. This potential breakthrough could be realized through the development of smart contact lenses (SCLs). Although contact lenses were first developed for eyesight correction, new uses have recently become available. In the near future, it might be possible to monitor a variety of ocular and systemic disorders using contact lens sensors. Within the realm of glaucoma, SCLs present a novel prospect, offering a potentially superior avenue compared to traditional management techniques. These lenses introduce the possibility of non-invasive and continuous monitoring of intraocular pressure (IOP) while also enabling the personalized administration of medication as and when needed. This convergence holds great promise for advancing glaucoma care. In this review, recent developments in SCLs, including their potential applications, such as IOP and glucose monitoring, are briefly discussed.

Oxygen-Deficient Bioceramics: Combination of Diagnosis, Therapy, and Regeneration

The journey of ceramics in medicine has been synchronized with an evolution from the first generation-alumina, zirconia, etc.-to the third -3D scaffolds. There is an up-and-coming member called oxygen-deficient or colored bioceramics, which have recently found their way through biomedical applications. The oxygen vacancy steers the light absorption toward visible and near infrared regions, making the colored bioceramics multifunctional-therapeutic, diagnostic, and regenerative. Oxygen-deficient bioceramics are capable of turning light into heat and reactive oxygen species for photothermal and photodynamic therapies, respectively, and concomitantly yield infrared and photoacoustic images. Different types of oxygen-deficient bioceramics have been recently developed through various synthesis routes. Some of them like TiO2- x , MoO3- x , and WOx have been more investigated for biomedical applications, whereas the rest have yet to be scrutinized. The most prominent advantage of these bioceramics over the other biomaterials is their multifunctionality endowed with a change in the microstructure. There are some challenges ahead of this category discussed at the end of the present review. By shedding light on this recently born bioceramics subcategory, it is believed that the field will undergo a big step further as these platforms are naturally multifunctional.

An Ex Vivo Pilot Study to Assess the Feasibility of 3D Printing of Orbital Implants in Horses

Severe ophthalmic conditions such as trauma, uveitis, corneal damage, or neoplasia can lead to eye removal surgery. Poor cosmetic appearance resulting from the sunken orbit ensues. The aim of this study was to demonstrate the feasibility of manufacturing a custom-made 3D-printed orbital implant made of biocompatible material for the enucleated horse and usable in conjunction to a corneoscleral shell. Blender, a 3D-image software, was used for prototype design. Twelve cadaver heads of adult Warmbloods were collected from the slaughterhouse. On each head, one eye was removed via a modified transconjunctival enucleation while the contralateral eye was kept intact as control. Ocular measurements were collected on each enucleated eye with the help of a caliper and used for prototype sizing. Twelve custom-made biocompatible porous prototypes were 3D-printed in BioMed Clear resin using the stereolithography technique. Each implant was fixated into the corresponding orbit, within the Tenon capsule and conjunctiva. Heads were frozen and thin slices were then cut in the transverse plane. A scoring system based on four criteria (space for ocular prosthesis, soft-tissue-coverage, symmetry to the septum, and horizontal symmetry), ranging from A (proper fixation) to C (poor fixation), was developed to evaluate implantation. The prototypes reached our expectations: 75% of the heads received an A score, and 25% a B score. Each implant cost approximately 7.30€ and took 5 hours for 3D-printing. The production of an economically accessible orbital implant made of biocompatible porous material was successful. Further studies will help determine if the present prototype is usable in vivo.

Recent advances of smart materials for ocular drug delivery

Owing to the variety and complexity of ocular diseases and the natural ocular barriers, drug therapy for ocular diseases has significant limitations, such as poor drug targeting to the site of the disease, poor drug penetration, and short drug retention time in the vitreous body. With the development of biotechnology, biomedical materials have reached the "smart" stage. To date, despite their inability to overcome all the aforementioned drawbacks, a variety of smart materials have been widely tested to treat various ocular diseases. This review analyses the most recent developments in multiple smart materials (inorganic particles, polymeric particles, lipid-based particles, hydrogels, and devices) to treat common ocular diseases and discusses the future directions and perspectives regarding clinical translation issues. This review can help researchers rationally design more smart materials for specific ocular applications.

Advances and Prospects in Materials for Craniofacial Bone Reconstruction

The craniofacial region is composed of 23 bones, which provide crucial function in keeping the normal position of brain and eyeballs, aesthetics of the craniofacial complex, facial movements, and visual function. Given the complex geometry and architecture, craniofacial bone defects not only affect the normal craniofacial structure but also may result in severe craniofacial dysfunction. Therefore, the exploration of rapid, precise, and effective reconstruction of craniofacial bone defects is urgent. Recently, developments in advanced bone tissue engineering bring new hope for the ideal reconstruction of the craniofacial bone defects. This report, presenting a first-time comprehensive review of recent advances of biomaterials in craniofacial bone tissue engineering, overviews the modification of traditional biomaterials and development of advanced biomaterials applying to craniofacial reconstruction. Challenges and perspectives of biomaterial development in craniofacial fields are discussed in the end.

Polyester 5-0 suture for porous implant placement after retinoblastoma enucleation: analysis of 120 sockets

BACKGROUND

Techniques used to suture the rectus muscle to the implant can influence the implant-related complications which is still a major problem following retinoblastoma enucleation. The goals of this work were to report the efficacy among patients with retinoblastoma who underwent enucleation followed by porous implant placement with the rectus muscles sutured with 5-0 polyester suture.

METHODS

This was a retrospective study of consecutive patients with retinoblastoma who underwent primary enucleation and porous implant placement with the rectus muscles tagged and sutured to the implant with polyester 5-0 suture. All the patients were followed up for a minimum of 2 years. The main outcome measure was implant exposure. The secondary efficacy measures were other implant-related complications.

RESULTS

Between May 2016 and December 2018, a total of 120 patients (120 eyes) underwent primary enucleation and porous implant placement were included. Postoperatively, 10/120 (8.3%) eyes developed exposure or conjunctival granuloma. Exposure was the most common postoperative complication (7/10, 70.0%). There were no cases of implant extrusion, migration, or infection.

CONCLUSIONS

Polyester 5-0 sutures are successful in patients with retinoblastoma who underwent enucleation followed by porous implant placement. Complications are minimal. Polyester 5-0 sutures were not associated with unacceptable complications in this pediatric population.

An Orbital Mystery: A Unique Case of an Obsolete Orbital Implant With a Review of Orbital Implant Materials

Orbital implant materials have evolved greatly over the past century and include but are not limited to metal, ceramic, polymer, silicone, and glass. Knowledge of historically used materials is clinically relevant to patient care as certain materials carry a greater risk of migration, extrusion, infection, and limitations for imaging modalities utilized to visualize adjacent structures. We report an unusual case of an 80-year-old male who presented to our community hospital with seizure-like activity. CT imaging of the brain revealed several white matter and cortex lesions with the largest lesion measuring 2.5 × 2 × 1.9 cm. The patient had a history of enucleation with placement of an orbital implant following a penetrating injury to the left eye at four years of age. Hounsfield scale analysis was read by radiology as being most consistent with a thin metallic shell surrounding the orbital implant. The potential for metallic material was consistent with the implant's age and time of placement. Few reviews on ocular implant materials from this period exist in the current medical literature. A single case report discussing a hollow metal orbital implant with similar-appearing imaging was identified. Due to concern for possible metal implant materials, the patient underwent implant exchange so MRI imaging could safely be performed. Intraoperatively, the implant was identified as a clear, hollow, non-metallic, non-porous polymer sphere. Following surgery, the patient was able to undergo appropriate neuroimaging with subsequent diagnostic biopsy. Current literature reviewing CT or photographic imaging of ocular implant devices prior to the 1940s is limited. This case highlights the importance of detailing materials historically used in orbital implants, their effects on clinical decision-making, and the utility of Hounsfield scale values to identify a material's radiodensity on CT imaging.

Polymeric biomaterials in the treatment of posterior segment diseases

Polymeric biomaterials are biological or synthetic substances which can be engineered to interact with biological systems for the diagnosis or treatment of diseases. These biomaterials have immense potential for treating eyes diseases, particularly the retina—a site of many inherited and acquired diseases. Polymeric biomaterials can be engineered to function both as an endotamponade agent and to prevent intraocular scarring in retinal detachment repair surgeries. They can also be designed as a drug delivery platform for treatment of retinal diseases. Finally, they can be used as scaffolds for cellular products and provide non-viral gene delivery solutions to the retina. This perspective article explains the role of polymeric biomaterials in the treatment of retinal conditions by highlighting recent advances being translated to clinical practice. The article will also identify potential hurdles to clinical translation as future research directions in the field.

Copper-Doped Bioactive Glass/Poly (Ether-Ether-Ketone) Composite as an Orbital Enucleation Implant in a Rabbit Model: An In Vivo Study

An orbital enucleation implant is used to compensate for the orbital volume deficits in the absence of the globe. In this work, copper-doped bioactive glass in poly(ether-ether-ketone) (CuBG/PEEK) composite scaffolds as an orbital enucleation implant were designed and fabricated by cool-pressed sintering and particle-leaching techniques, the incorporation of copper-doped bioactive glass in poly(ether-ether-ketone) (CuBG/PEEK) was expected to significantly improve the biocompatibility of the PEEK implant. The consequences after implantation of the CuBG/PEEK composite scaffolds in experimental, eviscerated rabbits was observed and assayed in term of histopathological examination. In detail, 24 rabbits were randomly divided into three groups: Group A, PEEK scaffolds; Group B, 20% CuBG/PEEK composite scaffolds; Group C, 40% CuBG/PEEK composite scaffolds; the rabbits were sacrificed at week 4 and week 12, followed by histochemical staining and observation. As a result, the PEEK group exhibited poor material exposure and tissue healing, while the CuBG/PEEK scaffolds showed good biocompatibility, and the 40% CuBG/PEEK composite scaffold exhibited the best performance in angiogenesis and tissue repair. Therefore, this study demonstrates the potential of CuBG/PEEK composite scaffolds as an orbital enucleation implant.

Association between Subjective and Objective Assessment of Enucleation Outcome Depending on the Presence of an Orbital Implant in Patients with Uveal Melanoma

We aimed to assess the cosmetic outcome of patients who underwent enucleation for uveal melanoma. The subjective assessment was based on a questionnaire, including four questions on postoperative cosmetic outcome. As part of the objective assessment, the following features were evaluated using a four-point scale: the symmetry of the upper eyelid sulcus, color matching between the prosthetic and healthy eye, prosthetic eye motility, and eyelid position. We enrolled 90 patients after enucleation (58 with and 32 without an orbital implant). The overall subjective assessment scores were 3.5/4 and 3.3/4 points in patients with and without an implant, respectively. The overall objective assessment scores were 3.3/4 and 2.3/4 in patients with and without an implant, respectively (p < 0.001). The cosmetic outcome was rated significantly higher by patients than by investigators (p < 0.05). There was no significant association between the overall subjective and objective assessment of the cosmetic outcome in any of the groups. Cosmetic outcome after enucleation for uveal melanoma was highly rated by patients. It was rated higher by patients than by investigators. The presence of an orbital implant was associated with higher objective assessment scores in terms of the symmetry of the upper lid sulcus, prosthetic eye motility, and eyelid position.

The Evolution of Orbital Implants and Current Breakthroughs in Material Design, Selection, Characterization, and Clinical Use

It is occasionally essential to surgically remove the damaged eye of the patient in the case of serious oculoorbital injuries, intraocular cancers, and other life-threatening diseases. An orbital implant is placed into the anophthalmic socket after the eye is removed to provide adequate volume reinstatement and revamp the cosmetic look of a normal eye. In the previous few decades, implant design and material selection criteria have progressed from basic nonporous polymeric spheres to devices with more complicated shapes and functions to ensure improved long-term clinical results. Because of their highly interconnected porous design, ceramic and polymeric porous implants have found popularity as a passive framework for fibrovascular ingrowth, with lower obstacle rates and the option of setting to improve prosthetic eye mobility. These materials, however, are not without flaws. The danger of migration and extrusion, infections after surgery, and poor motility transferred to the cosmetic ocular prosthesis are important elements of orbital implants of today. As a result, the development of novel biomaterials with improved functionalities (i.e., antibacterial effect, angiogenesis, and in situ moldability) that allow better eye replacement is more desirable than ever, highlighting one of the most challenging aspects of research topics in the field of ocular implants. This study highlights the history of orbital implants. It gives an outline of current advancements in the area, over and above some essential observations for materials design, selection, characterization, and transformation to clinical applications.

Integrating pore architectures to evaluate vascularization efficacy in silicate-based bioceramic scaffolds

Pore architecture in bioceramic scaffolds plays an important role in facilitating vascularization efficiency during bone repair or orbital reconstruction. Many investigations have explored this relationship but lack integrating pore architectural features in a scaffold, hindering optimization of architectural parameters (geometry, size and curvature) to improve vascularization and consequently clinical outcomes. To address this challenge, we have developed an integrating design strategy to fabricate different pore architectures (cube, gyroid and hexagon) with different pore dimensions (∼350, 500 and 650 μm) in the silicate-based bioceramic scaffolds via digital light processing technique. The sintered scaffolds maintained high-fidelity pore architectures similar to the printing model. The hexagon- and gyroid-pore scaffolds exhibited the highest and lowest compressive strength (from 15 to 55 MPa), respectively, but the cube-pore scaffolds showed appreciable elastic modulus. Moreover, the gyroid-pore architecture contributed on a faster ion dissolution and mass decay in vitro. It is interesting that both μCT and histological analyses indicate vascularization efficiency was challenged even in the 650-μm pore region of hexagon-pore scaffolds within 2 weeks in rabbit models, but the gyroid-pore constructs indicated appreciable blood vessel networks even in the 350-μm pore region at 2 weeks and high-density blood vessels were uniformly invaded in the 500- and 650-μm pore at 4 weeks. Angiogenesis was facilitated in the cube-pore scaffolds in comparison with the hexagon-pore ones within 4 weeks. These studies demonstrate that the continuous pore wall curvature feature in gyroid-pore architecture is an important implication for biodegradation, vascular cell migration and vessel ingrowth in porous bioceramic scaffolds.

Amplitude of movements with conical or spherical implants in anophthalmic socket

PURPOSE

To evaluate the amplitude of movement in anophthalmic sockets reconstructed with conical or spherical orbital implants with and without an external ocular prosthesis (EOP), and whether the fornix depth could play a role.

METHODS

Prospective observational study involving unilateral anophthalmic sockets evaluated the amplitude of movement with conical (20 subjects) or spherical (16) non-porous orbital implants, with and without an EOP, having the contralateral eye as the control group. Standardized photographs were obtained in the four gaze directions and measurements were performed using the Image J software. The upper and lower fornix depths were measured using rulers.

RESULTS

Compared to the contralateral eye, the median movement amplitude without EOP was smaller with conical implants in supraduction (-0.88 mm, p=0.008), abduction (-2.26 mm, p<0.001) and adduction (-0.91 mm, p=0.008). Spherical implants had reduced movement only in abduction (-2.63 mm, p<0.001). Conical and spherical implants had similar amplitudes of movement in all versions, and were always smaller compared to the control. The median movement amplitude with the EOP was -3.05 mm (p=0.001) than without the EOP in abduction and -2.07 mm (p=0.020) in adduction, regardless of implant format. The fornix depth did not affect the orbital implants or EOP movement amplitude's median.

CONCLUSION

Conical and spherical implants provide similar amplitude of movement and fornix depth did not have an influence on it. The amplitude of movement was significantly limited compared to the contralateral eye and was even more reduced if the EOP was in place with conical or spherical implant formats.

Conical Biosilicate Implant for Volume Augmentation in Anophthalmic Sockets

The ideal implant for anophthalmic socket reconstruction has yet to be developed. Biosilicate, a highly bioactive glass-ceramic, has been used in the composition of conical implants, which were initially tested in rabbit orbits with excellent results. However, the use of this material and the conical shape of the implants require further study in the human anophthalmic socket. Thus, we propose the use of a new conical implant composed of Biosilicate for orbital volume augmentation in anophthalmic sockets. This prospective, randomized study included 45 patients receiving conical implants composed of either Biosilicate or polymethylmethacrylate (control). Patients were evaluated clinically before and 7, 30, 60, 120, and 180 days after implantation. Systemic evaluations, laboratory tests, and computed tomography of the orbits were performed preoperatively and 180 days postoperatively. Both groups had good outcomes with no significant infectious or inflammatory processes. Only 1 patient, in the Biosilicate group, had early implant extrusion. Laboratory tests were normal in both groups. Computed tomography scans showed that the implants in both groups were well positioned. The new conical implant composed of Biosilicate was successfully used for anophthalmic socket reconstruction. This implant may provide a good alternative to the only conical implant currently available on the market, which is composed of porous polyethylene.

Tissue engineering approaches towards the regeneration of biomimetic scaffolds for age-related macular degeneration

Age-related macular degeneration (AMD) is the third major cause of blindness in people aged above 60 years. It causes dysfunction of the retinal pigment epithelium (RPE) and leads to an irreversible loss of central vision. The present clinical treatment options are more palliative in controlling the progression of the disease and do not functionally restore the degenerated RPE monolayer and photoreceptors. Currently, the clinical transplantation of RPE cells has shown poor engraftment potential due to the absence of an intact Bruch's membrane in AMD patients, thereby the vision is unable to be restored completely. Although tissue engineering strategies target the development of Bruch's membrane-mimetic substrates, the challenge still lies in the development of an ultrathin, biologically and mechanically equivalent membrane to restore visual acuity. Further, existing limitations such as cellular aggregation, surgical complications including retinal tissue damage, tissue rejection, disease transmission, inferior mechanical strength, and the loss of vision over time demand the search for an ideal strategy to restore the functional RPE. Hence, this review aims to provide insights into various approaches, from conventional cell therapy to 3D bioprinting, and their unmet challenges in treating AMD by outlining the pathophysiology of AMD and the host tissue response with respect to injury, treatment and preclinical animal models.

Custom-made artificial eyes using 3D printing for dogs: A preliminary study

Various incurable eye diseases in companion animals often result in phthisis bulbi and eye removal surgery. Currently, the evisceration method using silicone balls is useful in animals; however, it is not available to those with impaired cornea or severe ocular atrophy. Moreover, ocular implant and prostheses are not widely used because of the diversity in animal size and eye shape, and high manufacturing cost. Here, we produced low-cost and customized artificial eyes, including implant and prosthesis, using computer-aided design and three-dimensional (3D) printing technique. For 3D modeling, the size of the artificial eyes was optimized using B-mode ultrasonography. The design was exported to STL files, and then printed using polycaprolactone (PCL) for prosthesis and mixture of PCL and hydroxyapatite (HA) for ocular implant. The 3D printed artificial eyes could be produced in less than one and half hour. The prosthesis was painted using oil colors and biocompatible resin. Two types of eye removal surgery, including evisceration and enucleation, were performed using two beagle dogs, as a preliminary study. After the surgery, the dogs were clinically evaluated for 6 months and then histopathological evaluation of the implant was done. Ocular implant was biocompatible and host tissue ingrowth was induced after in vivo application. The custom-made prosthesis was cosmetically excellent. Although long-term clinical follow-up might be required, the use of 3D printed-customized artificial eyes may be beneficial for animals that need personalized artificial eye surgery.

Regulation of the Ocular Cell/Tissue Response by Implantable Biomaterials and Drug Delivery Systems

Therapeutic advancements in the treatment of various ocular diseases is often linked to the development of efficient drug delivery systems (DDSs), which would allow a sustained release while maintaining therapeutic drug levels in the target tissues. In this way, ocular tissue/cell response can be properly modulated and designed in order to produce a therapeutic effect. An ideal ocular DDS should encapsulate and release the appropriate drug concentration to the target tissue (therapeutic but non-toxic level) while preserving drug functionality. Furthermore, a constant release is usually preferred, keeping the initial burst to a minimum. Different materials are used, modified, and combined in order to achieve a sustained drug release in both the anterior and posterior segments of the eye. After giving a picture of the different strategies adopted for ocular drug release, this review article provides an overview of the biomaterials that are used as drug carriers in the eye, including micro- and nanospheres, liposomes, hydrogels, and multi-material implants; the advantages and limitations of these DDSs are discussed in reference to the major ocular applications.

Orbital floor repair using patient specific osteoinductive implant made by stereolithography

The orbital floor (OF) is an anatomical location in the craniomaxillofacial (CMF) region known to be highly variable in shape and size. When fractured, implants commonly consisting of titanium meshes are customized by plying and crude hand-shaping. Nevertheless, more precise customized synthetic grafts are needed to meticulously reconstruct the patients' OF anatomy with better fidelity. As alternative to titanium mesh implants dedicated to OF repair, we propose a flexible patient-specific implant (PSI) made by stereolithography (SLA), offering a high degree of control over its geometry and architecture. The PSI is made of biodegradable poly(trimethylene carbonate) (PTMC) loaded with 40 wt % of hydroxyapatite (called Osteo-PTMC). In this work, we developed a complete work-flow for the additive manufacturing of PSIs to be used to repair the fractured OF, which is clinically relevant for individualized medicine. This work-flow consists of (i) the surgical planning, (ii) the design of virtual PSIs and (iii) their fabrication by SLA, (iv) the monitoring and (v) the biological evaluation in a preclinical large-animal model. We have found that once implanted, titanium meshes resulted in fibrous tissue encapsulation, whereas Osteo-PMTC resulted in rapid neovascularization and bone morphogenesis, both ectopically and in the OF region, and without the need of additional biotherapeutics such as bone morphogenic proteins. Our study supports the hypothesis that the composite osteoinductive Osteo-PTMC brings advantages compared to standard titanium mesh, by stimulating bone neoformation in the OF defects. PSIs made of Osteo-PTMC represent a significant advancement for patients whereby the anatomical characteristics of the OF defect restrict the utilization of traditional hand-shaped titanium mesh.

Genipin-crosslinked polyvinyl alcohol/silk fibroin/nano-hydroxyapatite hydrogel for fabrication of artificial cornea scaffolds-a novel approach to corneal tissue engineering

Design of artificial corneal scaffolds substitute is crucial for replacement of impaired cornea. In this paper, porous polyvinyl alcohol/silk fibroin/nano-hydroxyapatite (PVA/SF/n-HA) composite hydrogel was prepared via the genipin (GP) cross-linking, the pore diameter of the hydrogel ranged from 8.138 nm and 90.269 nm, and the physical and physiological function of hydrogel were investigated. The resulting hydrogel exhibited favourable physical properties. With the GP content increasing, the structural regularity of PVA/SF/n-HA composite hydrogel was enhanced and the thermal stability was improved. The moisture content was slightly decreased and generally maintained at approximately 70%. The tensile strength was heightened up to 0.64 MPa, while the breaking elongation was decreased slightly. Moreover, the biofunction was investigated. The in vitro degradation test demonstrated that with the addition of GP, the stability of the composite hydrogels in protease XIV solution was promoted and the three-dimensional porosity structure of composite hydrogels was maintained as ever. And the human corneal fibroblasts (HCFs) were employed to examine the cells cytotoxicity of the PVA/SF/n-HA composite hydrogels with different GP content by CCK-8 assay. Based on confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM), HCFs had individually commendable adhesion and proliferation on PVA/n-HA/SF composite hydrogel. HCFs proliferated and grew into the pores of composite hydrogel. The results of biocompatibility experiments of composite hydrogel suggested that it was no acute toxicity, in vitro cytotoxicity was 0 or 1 grade. Overall, results from this paper, PVA/n-HA/SF composite hydrogel was a qualified medical material which conformed to the national standard, could be a promising alternative for artificial cornea scaffold material-a novel approach to corneal tissue engineering.

Simultaneous enhancement of vascularization and contact-active antibacterial activity in diopside-based ceramic orbital implants

Rapid vascularization and long-term antibacterial property are desirable characteristics of the next-generation implants in orbital reconstruction. In this study, the new diopside-based orbital implants were developed by direct ink writing of diopside (CaMgSi₂O₆; DIO) and low-melt bioactive glass (BG)-assisted sintering approaches. The mechanical tests showed that the addition 5% or 10% BG could readily enhance the compressive strength of the DIO porous bioceramics after sintering at 1150 °C. The Tris buffer immersion test in vitro indicated that the porous bioceramics exhibited appreciable mechanical stability and very limited mass loss (<3.5%) after 8 weeks. The DIO/10BG porous bioceramic sintered at 1150 °C or 1250 °C could promote appreciable angiogenesis response at the early stage (2-6 weeks) of implantation in the rabbit panniculus carnosus muscle models in vivo. It is interesting that the steam autoclaved bioceramics exhibited outstanding contact-active inhibition against Staphylococcus aureus and Pseudomonas aeruginosa, but as-sintered bioceramics showed no antibacterial effect. It is reasonable to consider that our strategy paves the way toward a simple and effective approach to fabricate the multifunctional tailormade implants for orbital implantation, thus accelerating the clinical translation of biomaterials research.

Effect of surface microstructure on the anti-fibrosis/adhesion of hydroxyapatite ceramics in spinal repair of rabbits

Epidural adhesion is a great clinical challenge after laminectomy. In the present study, two types of hydroxyapatite (HA) laminas with distinct surface microstructures were prepared by cold isostatic pressing (CIP) and slip casting (SC) techniques, and investigated to their anti-fibrosis/adhesion effects by in vitro and in vivo evaluations. In contrast with the dense HA-CIP, HA-SC had a large number of micropores on the surface. After cultured on both HA ceramics, human skin fibroblasts presented the obvious senescent feature, and CCN1 gene expression was significantly up-regulated. HA-SC induced higher CCN1 gene expression than HA-CIP. After used for closing the lost vertebral after laminectomy in rabbits, both HA laminas promoted the recovery of the bony structure as well as prevented the hyperplastic fibrous tissue from penetration into the spinal canal area and inhibited the formation of scar-like tissue in laminectomy sites to some extent. Besides, thinner layer of fibrous tissue and smaller gap between the implant surface and paravertebral muscles were found in HA-CIP than HA-SC. Therefore, HA ceramics could have good anti-fibrosis/adhesion effect when used in spinal repair, and the dense HA-CIP could be an ideal choice. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B:2629-2637, 2019.

Bio Mimicking of Extracellular Matrix

Biomaterials play a critical role in regenerative strategies such as stem cell-based therapies and tissue engineering, aiming to replace, remodel, regenerate, or support damaged tissues and organs. The design of appropriate three-dimensional (3D) scaffolds is crucial for generating bio-inspired replacement tissues. These scaffolds are primarily composed of degradable or non-degradable biomaterials and can be employed as cells, growth factors, or drug carriers. Naturally derived and synthetic biomaterials have been widely used for these purposes, but the ideal biomaterial remains to be found. Researchers from diversified fields have attempted to design and fabricate novel biomaterials, aiming to find novel theranostic approaches for tissue engineering and regenerative medicine. Since no single biomaterial has been found to possess all the necessary characteristics for an ideal performance, over the years scientists have tried to develop composite biomaterials that complement and combine the beneficial properties of multiple materials into a superior matrix. Herein, we highlight the structural features and performance of various biomaterials and their application in regenerative medicine and for enhanced tissue engineering approaches.

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 semi-smooth 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 the total 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.

Anophthalmic Sockets in Retinoblastoma: A Single Center Experience

PURPOSE

To evaluate outcomes of anophthalmic sockets in retinoblastoma at a tertiary care center in Singapore.

DESIGN

A retrospective study.

METHODS

Patients who underwent enucleation as sole/part of treatment for retinoblastoma were reviewed at our center from 2005-2017. Details including demographics, grouping and staging, adjuvant therapy, surgery, implant, and complications were collected.

RESULTS

Of 42 patients with retinoblastoma managed over the period, the anophthalmic sockets of 31 patients who underwent enucleation were analyzed. Mean age at enucleation was 2 years. Twenty-three enucleations were performed at our institution and 8 enucleations had been performed elsewhere. Seventeen patients (52%) had porous polypropylene, 9 patients (27%) had polymethylmethacrylate, 1 patient (3%) had glass implant, and 3 (9%) had dermis fat graft. The sizes of implants varied from 10 to 20 mm. Twelve patients had attempts at globe salvation before enucleation. Out of 28 patients with primary orbital implants, 3 had implant exposure. The rates of repeat surgery among patients with and without primary implant were 66.67% (2 out of 3) and 10.7% (3 out of 28), respectively. One patient had postenucleation socket syndrome with stock eye. Five patients referred for enucleation were conservatively managed.

CONCLUSIONS

Anophthalmic sockets in retinoblastoma have long-term implications if the primary procedure is not performed well. While the majority had good outcomes (structural and esthetic), a minority had complications requiring intervention. Ophthalmologists managing retinoblastoma must be aware of these. Primary implant had favorable outcome with minimal complications.

Nanoscale Topographical Characterization of Orbital Implant Materials

The search for an ideal orbital implant is still ongoing in the field of ocular biomaterials. Major limitations of currently-available porous implants include the high cost along with a non-negligible risk of exposure and postoperative infection due to conjunctival abrasion. In the effort to develop better alternatives to the existing devices, two types of new glass-ceramic porous implants were fabricated by sponge replication, which is a relatively inexpensive method. Then, they were characterized by direct three-dimensional (3D) contact probe mapping in real space by means of atomic force microscopy in order to assess their surface micro- and nano-features, which were quantitatively compared to those of the most commonly-used orbital implants. These silicate glass-ceramic materials exhibit a surface roughness in the range of a few hundred nanometers (S_q within 500–700 nm) and topographical features comparable to those of clinically-used “gold-standard” alumina and polyethylene porous orbital implants. However, it was noted that both experimental and commercial non-porous implants were significantly smoother than all the porous ones. The results achieved in this work reveal that these porous glass-ceramic materials show promise for the intended application and encourage further investigation of their clinical suitability.

Concerns of anophthalmic patients-a comparison between cryolite glass and polymethyl methacrylate prosthetic eye wearers

PURPOSE

To compare the concerns of experienced cryolite glass and (poly)methyl methacrylate (PMMA) prosthetic eye wearers.

METHODS

One hundred six experienced cryolite glass and 63 experienced PMMA prosthetic eye wearers completed an anonymous questionnaire regarding general and specific prosthetic eye concerns at least 2 years after natural eye loss. From these independent anophthalmic populations, we identified 34 case-control pairs matched for the known influencing demographic variables of gender, occupation, age, and time since natural eye loss.

RESULTS

The levels of concern were significantly lower in the cryolite glass group than those in the PMMA group for the following: loss of balance (p < 0.001), phantom sight vision (p < 0.001), pain (p < 0.001), receiving good advice (p = 0.001), fullness of orbit (p = 0.001), size (p = 0.007), direction of gaze relative to the healthy fellow eye (p = 0.005), eye lid contour (p = 0.037), comfort of the prosthetic eye (p < 0.001), colour relative to the healthy fellow eye (p < 0.001), and retention of the prosthetic eye (p < 0.001). Concerns about watering, crusting, discharge, visual perception, appearance, movement of the prosthetic eye, and health of the remaining eye were not significantly different between both groups.

CONCLUSIONS

The results of this study showed that many general and specific levels of concern were significantly lower for cryolite glass prosthetic eye wearers than for PMMA prosthetic eye wearers. The question of why there are significant differences and to what extent the material of the prosthesis (cryolite glass or PMMA) has an impact on various concerns remains unanswered and should be addressed in a prospective comparative multicentre trial.

Porous orbital implant after enucleation in retinoblastoma patients: indications and complications

This study aims to identify risk factors associated with complications in retinoblastoma patients following primary and secondary enucleations with porous implant placement. A retrospective case-control study was performed between 2010 and 2015. Data pertaining to subjects' demographics, medical history, clinical, and pathological findings, implant characteristics and complications were collected. The analysis included 103 eyes of 101 patients age 27.8 ± 21.9 months undergoing enucleation for retinoblastoma. Postoperatively, 19/103 (18%) eyes developed exposure, extrusion, or hematoma requiring subsequent surgery. Exposure was the most common postoperative complication (12/19, 63%). Age at enucleation 24 months or younger, Hispanic ethnicity, female gender, and intravenous chemotherapy prior to enucleation were associated with increased odds of implant complications. In contrast, patients who were given intravitreal melphalan (IM), subtenons carboplatin (SC), or external beam radiation therapy (EBRT) did not demonstrate an increased risk of complications. In this cohort of retinoblastoma patients undergoing primary or secondary enucleation with porous implants, implant exposure was the most common postoperative complication. Our findings suggest that female gender, Hispanic ethnicity, age at enucleation 24 months or younger, and intravenous chemotherapy prior to enucleation may increase the risk of complications.

Nano-engineering safer-by-design nanoparticle based moth-eye mimetic bactericidal and cytocompatible polymer surfaces

Nanotechnology provides a new design paradigm for alternative antibacterial strategies in the fight against drug-resistant bacteria. In this paper, the enhanced bactericidal action of moth-eye nanocomposite surfaces with a collaborative nanoparticle functional and topography structural mode of action is reported. The moth-eye nanocomposite surfaces are fabricated in combined processing steps of nanoparticle coating and surface nanoimprinting enabling the production of safer-by-design nanoparticle based antibacterial materials whereby the nanoparticle load is minimized whilst bactericidal efficiency is improved. The broad antibacterial activity of the nanocomposite moth-eye topographies is demonstrated against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli and Pseudomonas aeruginosa as model bacteria. The antibacterial performance of the moth-eye nanocomposite topographies is notably improved over that of the neat moth-eye surfaces with bacteria inhibition efficiencies up to 90%. Concurrently, the moth-eye nanocomposite topographies show a non-cytotoxic behaviour allowing for the normal attachment and proliferation of human keratinocytes.

Moth-eye nanocomposite surfaces are fabricated in combined processing steps of nanoparticle coating and surface nanoimprinting enabling the production of safer-by-design antibacterial nanoparticle-based materials.

Osseointegrated Implants and Prosthetic Reconstruction Following Skull Base Surgery

Rehabilitation following ablative skull base surgery remains a challenging task, given the complexity of the anatomical region, despite the recent advances in reconstructive surgery. Remnant defects following resection of skull base tumors are often not amenable to primary closure. As such, numerous techniques have been described for reconstruction, including local rotational muscle flaps, pedicled flaps with skin paddle, or even free tissue transfer. However, not all patients are appropriate surgical candidates and therefore may instead benefit from nonsurgical options for functional and aesthetic restoration. Osseointegrated implants and biocompatible prostheses provide a viable alternative for such a patient population. The purpose of this review serves to highlight current options for prosthetic rehabilitation of skull base defects and describe their indications, advantages, and disadvantages.

Collagen-Based Photoactive Agent for Tissue Bonding

Using a combination of methacrylated collagen and the photosensitizer rose Bengal, a new light-activated biomimetic material for tissue sutureless bonding was developed. This formulation was cross-linked using green light. In vivo tests in mice demonstrate the suitability of the material for sutureless wound closure.

[Ocular prosthetics. Fitting, daily use and complications]

BACKGROUND

Ocular prosthetics make a decisive contribution to the functional, esthetic and psychosomatic rehabilitation of patients after ocular extirpation.

OBJECTIVES

This article provides an overview of the fitting, daily care and complications of ocular prosthetics.

METHODS

The study comprised a PubMed literature review and own clinical results.

RESULTS

Ocular prosthetics made from cryolite glass or perspex can be manufactured and fitted 5-8 weeks after removal of the eye. During this period a conformer is placed within the conjunctival sac in order to prevent scar formation and shrinking of the socket. Artificial eyes can be worn continuously, only interrupted by a short but regular cleaning procedure. Artificial tears and lid hygiene improve the comfort of wearing. Glass prostheses have to be renewed every 1-2 years, while perspex prostheses need to be polished once a year. Complications, such as giant papillary conjunctivitis or blepharoconjunctivitis sicca are facilitated by poor fit, increased age and inappropriate care of the prosthetic device. In the case of socket shrinkage or anophthalmic socket syndrome, surgical interventions are needed to re-enable the use of an artificial eye.

CONCLUSION

Adequate fitting, daily care of ocular prosthetics and therapeutic management of associated complications are mandatory for a durable functional, esthetic and psychosomatic rehabilitation after ocular extirpation.

Fabrication of an Orbital Prosthesis Combined With Eyebrow Transplantation

Fabrication of an orbital prosthesis is considered as a challenging procedure as compared to the other facial prosthesis due to the presence of inactive eye movements and the need of artificial hair in order to mimic eyelashes and eyebrows. Generally these structures are sewed or bonded in the silicone. However, deformation or hair loss is observed within time. This deformation is visible especially in the eyebrow. This clinical report represents a patient with an implant supported orbital prosthesis. Patient was not satisfied with the nature of her eyebrow that was sewed in the silicone. Therefore, an alternative approach of eyebrow transplantation was used for the patient. The patient expressed her better satisfaction of this definitive prosthesis supported with eyebrow transplantation.

Facile fabrication of bioactive ultra-small protein–hydroxyapatite nanoconjugates via liquid-phase laser ablation and their enhanced osteogenic differentiation activity

Ultra-small protein–hydroxyapatite nanoconjugates promote the osteogenic differentiation of mesenchymal stem cells.

Integrated versus non-integrated orbital implants for treating anophthalmic sockets

BACKGROUND

Anophthalmia is the absence of one or both eyes, and it can be congenital (i.e. a birth defect) or acquired later in life. There are two main types of orbital implant: integrated, whereby the implant receives a blood supply from the body that allows for the integration of the prosthesis within the tissue; and non-integrated, where the implant remains separate. Despite the remarkable progress in anophthalmic socket reconstruction and in the development of various types of implants, there are still uncertainties about the real roles of integrated (hydroxyapatite (HA), porous polyethylene (PP), composites) and non-integrated (polymethylmethacrylate (PMMA)/acrylic and silicone) orbital implants in anophthalmic socket treatment.

OBJECTIVES

To assess the effects of integrated versus non-integrated orbital implants for treating anophthalmic sockets.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 7), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to August 2016), Embase (January 1980 to August 2016), Latin American and Caribbean Health Sciences Literature Database (LILACS) (1982 to August 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 8 August 2016.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of integrated and non-integrated orbital implants for treating anophthalmic sockets.

DATA COLLECTION AND ANALYSIS

Two authors independently selected relevant trials, assessed methodological quality and extracted data.

MAIN RESULTS

We included three studies with a total of 284 participants (250 included in analysis). The studies were conducted in India, Iran and the Netherlands. The three studies were clinically heterogenous, comparing different materials and using different surgical techniques. None of the included studies used a peg (i.e. a fixing pin used to connect the implant to the prosthesis). In general the trials were poorly reported, and we judged them to be at unclear risk of bias.One trial compared HA using traditional enucleation versus alloplastic implantation using evisceration (N = 100). This trial was probably not masked. The second trial compared PP with scleral cap enucleation versus PMMA with either myoconjunctival or traditional enucleation (N = 150). Although participants were not masked, outcome assessors were. The last trial compared HA and acrylic using the enucleation technique (N = 34) but did not report comparative effectiveness data.In the trial comparing HA versus alloplastic implantation, there was no evidence of any difference between the two groups with respect to the proportion of successful procedures at one year (risk ratio (RR) 1.02, 95% confidence interval (CI) 0.95 to 1.09, N = 100, low-certainty evidence). People receiving HA had slightly worse horizontal implant mobility compared to the alloplastic group (mean difference (MD) -3.35 mm, 95% CI -4.08 to -2.62, very low-certainty evidence) and slightly worse vertical implant motility (MD -2.76 mm, 95% CI -3.45 to -2.07, very low-certainty evidence). As different techniques were used - enucleation versus evisceration - it is not clear whether these differences in implant motility can be attributed solely to the type of material. Investigators did not report adverse events.In the trial comparing PP versus PMMA, there was no evidence of any difference between the two groups with respect to the proportion of successful procedures at one year (RR 0.92, 95% CI 0.84 to 1.01, N = 150, low-certainty evidence). There was very low-certainty evidence of a difference in horizontal implant motility depending on whether PP was compared to PMMA with traditional enucleation (MD 1.96 mm, 95% CI 1.01 to 2.91) or PMMA with myoconjunctival enucleation (-0.57 mm, 95% CI -1.63 to 0.49). Similarly, for vertical implant motility, there was very low-certainty evidence of a difference in the comparison of PP to PMMA traditional (MD 3.12 mm 95% CI 2.36 to 3.88) but no evidence of a difference when comparing PP to PMMA myoconjunctival (MD -0.20 mm 95% CI -1.28 to 0.88). Four people in the PP group (total N = 50) experienced adverse events (i.e. exposures) compared to 6/100 in the PMMA groups (RR 17.82, 95% CI 0.98 to 324.67, N = 150, very low-certainty evidence).None of the studies reported socket sphere size, cosmetic effect or quality of life measures.

AUTHORS' CONCLUSIONS

Current very low-certainty evidence from three small published randomised controlled trials did not provide sufficient evidence to assess the effect of integrated and non-integrated material orbital implants for treating anophthalmic sockets. This review underlines the need to conduct further well-designed trials in this field.

Experimental acrylonitrile butadiene styrene and polyamide evisceration implant: a rabbit clinical and histopathology study

ABSTRACT The purpose of this study was to evaluate acrylonitrile butadiene styrene (ABS) and polyamide implants in rabbits submitted to evisceration at the macroscopic and microstructure level and to assess clinical response and histopathological changes as well. For the experimental study implants of 12mm diameter were prepared by rapid prototyping, weighed and the outer and inner surfaces evaluated macroscopically and by electron microscopy. In addition, a compression test was performed and ultrastructural damage was then determined. After evisceration of the left eyeball, nine New Zealand rabbits received ABS implants and nine others received polyamide implants. The animals were assessed daily for 15 days after surgery and every seven days until the end of the study (90 days). Histopathological evaluation was performed at 15, 45 and 90 days after surgery. The ABS implants weighed approximately 0.44g, while the polyamide ones weighed 0.61g. Scanning electron microscopy demonstrated that the ABS implants had regular-sized, equidistant micropores, while the polyamide ones showed micropores of various sizes. The force required to fracture the ABS implant was 14.39 ±0.60 Mpa, while for the polyamide one, it was 16.80 ±1.05 Mpa. Fifteen days after surgery, we observed centripetal tissue infiltration and scarce inflammatory infiltrate. Implants may be used in the filling of anophthalmic cavities, because they are inert, biocompatible and allow tissue integration.

Orbital implants: State-of-the-art review with emphasis on biomaterials and recent advances

In the treatment of severe oculo-orbital traumas, intraocular malignancies or other life-threatening conditions it is sometimes necessary to surgically remove the patient's diseased eye. Following the removal of the eye, an orbital implant is inserted into the anophthalmic socket in order to provide satisfactory volume replacement and restore the aesthetic appearance of a normal eye. Over the last decades, the implant design and the criteria of materials selection evolved from simple non-porous polymeric sphere to devices with more complex shape and functionalities for ensuring better clinical outcomes in the long-term. Polymeric and ceramic porous implants have gained prominence since their highly interconnected porous architecture allows them to act as a passive framework for fibrovascular in-growth offering reduced complication rates and the possibility of pegging to enhance the motility of the artificial eye. However, there are still drawbacks to these materials. Some critical aspects of today's orbital implants include the risk of migration and extrusion, postoperative infections and low motility transmitted to the aesthetic ocular prosthesis. Hence, the development of novel biomaterials with enhanced functionalities (e.g. angiogenesis, antibacterial effect, in situ mouldability) which enable an improved outcome of eye replacement is more than ever desirable and represents one of the most challenging topics of research in the field of ocular implants. This review summarizes the evolution of orbital implants and provides an overview of the most recent advances in the field as well as some critical remarks for materials design, selection, characterization and translation to clinical applications.

Prosthetic rehabilitation of surgically treated orbital defects - evisceration, enucleation, and exenteration: A case series

The rehabilitation of a patient who has suffered the psychological trauma due to loss of an eye requires a prosthesis that will provide the optimum cosmetic and functional result. The mode of rehabilitation varies based on the type of defect and surgical approach being adopted. A case series of prosthetic rehabilitation of three types of orbital defects - evisceration, enucleation and exenteration have been reported in this article. The clinical relevance of surgical approaches highlights the preservation of remaining anatomic structures creating a negative space or concavity to aid in future prosthetic rehabilitation. A multidisciplinary management and team approach is essential in providing esthetics and to regain the confidence. Follow-up care for the patient is mandatory.

Bioceramics and Scaffolds: A Winning Combination for Tissue Engineering

In the last few decades, we have assisted to a general increase of elder population worldwide associated with age-related pathologies. Therefore, there is the need for new biomaterials that can substitute damaged tissues, stimulate the body’s own regenerative mechanisms, and promote tissue healing. Porous templates referred to as “scaffolds” are thought to be required for three-dimensional tissue growth. Bioceramics, a special set of fully, partially, or non-crystalline ceramics (e.g., calcium phosphates, bioactive glasses, and glass–ceramics) that are designed for the repair and reconstruction of diseased parts of the body, have high potential as scaffold materials. Traditionally, bioceramics have been used to fill and restore bone and dental defects (repair of hard tissues). More recently, this category of biomaterials has also revealed promising applications in the field of soft-tissue engineering. Starting with an overview of the fundamental requirements for tissue engineering scaffolds, this article provides a detailed picture on recent developments of porous bioceramics and composites, including a summary of common fabrication technologies and a critical analysis of structure–property and structure–function relationships. Areas of future research are highlighted at the end of this review, with special attention to the development of multifunctional scaffolds exploiting therapeutic ion/drug release and emerging applications beyond hard tissue repair.

A biomimetic collagen/heparin multi-layered porous hydroxyapatite orbital implant for in vivo vascularization studies on the chicken chorioallantoic membrane

BACKGROUND

The vascularization of an orbital implant is a key issue for reducing complications, such as exposure and infection.

METHODS

Here, we developed a facile layer-by-layer assembly approach to modify porous hydroxyapatite (pHA) orbital implants with five collagen (COL)/heparin (HEP) multilayers.

RESULTS

SEM characterization showed that the average pore size of the pHA/(COL/HEP)5 scaffold was 316.8 ± 77.1 μm. After being coated with five COL/HEP multilayers, the mechanical strength was improved compared with that of the pHA scaffolds. The in vitro assay displayed that the pHA scaffolds covered with COL/HEP multilayers resulted in a larger number of human umbilical vein endothelial cells after being cultured for 14 days. The macroscopic evaluation and semi-quantitative vascular density analysis of the chicken chorioallantoic membrane assay showed that the pHA/(COL/HEP)5 scaffolds resulted in more intense angiogenesis than the pHA scaffolds.

CONCLUSIONS

These studies demonstrate that the biomembrane-mimicking coating of COL/HEP multilayers is a simple and effective strategy to endow combined biological performances of pHA orbital implants and to potentially reduce implant-related complications.

Worldwide enucleation techniques and materials for treatment of retinoblastoma: an international survey

Purpose

To investigate the current practice of enucleation with or without orbital implant for retinoblastoma in countries across the world.

Methods

A digital survey identifying operation techniques and material used for orbital implants after enucleation in patients with retinoblastoma.

Results

We received a response of 58 surgeons in 32 different countries. A primary artificial implant is routinely inserted by 42 (72.4%) surgeons. Ten (17.2%) surgeons leave the socket empty, three (5.2%) decide per case. Other surgeons insert a dermis fat graft as a standard primary implant (n=1), or fill the socket in a standard secondary procedure (n=2; one uses dermis fat grafts and one artificial implants). The choice for porous implants was more frequent than for non-porous implants: 27 (58.7%) and 15 (32.6%), respectively. Both porous and non-porous implant types are used by 4 (8.7%) surgeons. Twenty-five surgeons (54.3%) insert bare implants, 11 (23.9%) use separate wrappings, eight (17.4%) use implants with prefab wrapping and two insert implants with and without wrapping depending on type of implant. Attachment of the muscles to the wrapping or implant (at various locations) is done by 31 (53.4%) surgeons. Eleven (19.0%) use a myoconjunctival technique, nine (15.5%) suture the muscles to each other and seven (12.1%) do not reattach the muscles. Measures to improve volume are implant exchange at an older age (n=4), the use of Restylane SQ (n=1) and osmotic expanders (n=1). Pegging is done by two surgeons.

Conclusion

No (worldwide) consensus exists about the use of material and techniques for enucleation for the treatment of retinoblastoma. Considerations for the use of different techniques are discussed.