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.

Reconstrucción de la cavidad orbitaria utilizando prótesis con fijación ósea / Reconstruction of the contracted socket, using solid prostesis with bone fixation

La obliteración de la cavidad ocular por retracción cicatricial que impide la colocación de una prótesis es un problema frecuente tras la enucleación del globo ocular, aunque se mantengan íntegras las estructuras óseas. Para que una prótesis ocular se mantenga en posición correcta son precisos fondos de saco superior e inferior amplios y profundos, no siendo tan importante la profundidad de la cavidad. Para conseguirlos, se han propuesto muchos métodos y aunque hemos probado varios de ellos, el índice de recidivas y fracasos era muy elevado, cerrándose los espacios y expulsándose la prótesis al cabo de poco tiempo. En este trabajo, se propone la colocación de una prótesis sólida, diseñada para llevar una fijación ósea, forrada con un injerto cutáneo laminar que tapiza el interior de los fondos de saco retro palpebrales neo formados. Esta prótesis y el injerto quedan así fijos, sin posibilidad de desplazamiento ni de deformación, durante un mínimo de tres meses, tiempo en el que la fuerza de retracción cicatricial cesa, y los fondos de saco quedan de modo definitivo. Nos permite además un fácil control postoperatorio y su tolerancia es excelente. Los resultados tras cuatro años han sido buenos y destacamos en este procedimiento la relación entre la sencillez de aplicación y su eficacia (AU)

The eye socket contraction due to cicatricial retraction, which stops the placement of a prosthesis, is a frequent problem after the enucleation of the ocular globe, although the whole osseous structures are maintained. In order to keep an ocular prosthesis in the right position, it is necessary to have a wide and deep upper and lower “cul-de-sac” not being so important the depth of the cavity to get them, many methods have been proposed; and although we have tried some of them, the relapse and failures index has been very high, because the spaces closed and the prosthesis was expelled after a short time. In this work, we propose to put a solid prosthesis, designed for holding an osseous fixation, covered with a laminar skin graft that will cover the inner part of the retropalpebral neoformated “cul-desac”. The prosthesis and the graft will remain fixed inmobile, with no possibility of movement or deformation, for a minimun period of time of three months, when the cicatricial relapse strength stops and the “cul –de-sac” remains definitively. It also allows us to have an easy postoperative control and excellent tolerance. After four years, the results have been good and we point out in this procedure the relationship between the simplicity of its application and its efficacy (AU)

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.

[Rehabilitation with bone anchored facial prostheses]. / Rehabilitation mit knochenverankerten Orbitaepithesen.

BACKGROUND: Rehabilitation of orbita defects with loss of eyelids is difficult to achieve with plastic surgery. Here defect coverage with a facial prosthesis shows good results. PATIENTS AND METHODS: 105 patients with orbita defects were treated since 1991 with bone anchored facial prostheses. Preoperatively we measured the bone availability with computed tomography. We inserted Brånemark-titanium implants (Fa. Nobel Biocare), with a two-stage procedure. After a period of at least three months we exposed implants and connected the supraconstruction. Then our anaplastologist produced the facial prosthesis, either a "soft" facial prosthesis of silicone or a "solid" prosthesis of polymethylmetacrylate (PMMA). Not later than every three months patients came to recall. RESULTS: For all patients we found enough bone for implantation. The implants were screwed into the lateral bony orbital margin. There were no intraoperative complications accompanying implant insertion. For 96 patients we chose the silicone material; for nine patients we did produce the facial prosthesis of PMMA. In about 10.5% of the implants we had to remove subcutaneous tissue in local anesthesia because of recurrent periimplantary inflammations. Three years after insertion 95.8% of the implants were still firmly anchored in the bone. CONCLUSIONS: Performed by the experienced specialist the prosthetic treatment of orbita defects with a bone anchored facial prosthesis is a cosmetically satisfactory procedure with good long-term outcome. While modern plastic materials can replace the lost tissue with deceptively natural results, the implants guarantee firm secure retention of the facial prosthesis.

Técnica cirúrgica para correçäo de miopia. Anel corneano intra-estromal / Myopia correction with intrastromal corneal ring

Os implantes intracorneanos para correçäo de ametropias vêm sendo pesquisados desde a década de 50. Os anéis corneanos intra estromais, por serem bem tolerados, vêm se destacando como um técnica alternativa segura para tratamento daas ametropias. Após prolongados estudos em animais, utilizando anéis com 5,00 mm de diâmetro e espessuras variáveis, reslizamos um implante em paciente míope e amblíope, no terço anterios do estroma corneano, utilizando a técnica de ceratectomia parcial. Após 3 anos de observaçäo clínica ficaram evidenciados e perfeita tolerância da córnea à prótese e a estabilidade do resultado refracional. Desenvolvemos a partir daí, uma técnica para implante do anel através de tunelizaçäo do estroma. Selecionamos um paciente míope, anisométrope e amblíope e realizamos a cirurgia. O resultado, após o primeiro mês de observaçäo, mostrou boa tolerância além de um aplanamento central da córnea de 3,00 dioptrias confirmado tanto pela ceratometria quanto pelo topografia corneana computadorizada. Embora o período de observaçäo seja muito pequeno, podemos afirmar, embasados em nossos estudos preliminares, que esta técnica representa uma alternativa promissora para o tratamento dos erros refracionais