Experimental acrylonitrile butadiene styrene and polyamide evisceration implant: a rabbit clinical and histopathology study / Estudo clínico e histopatológico em coelhos eviscerados com utilização de implantes de poliamida e acrilonitrila butadieno estireno

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.(AU)

Avaliou-se a macroscopia, a microestrutura, a resposta clínica e histopatológica de implantes de acrilonitrila butadieno estireno (ABS) e poliamida em coelhos submetidos à evisceração. Para o estudo experimental, os implantes foram elaborados por meio de prototipagem rápida, com 12mm de diâmetro, pesados e tiveram suas superfícies avaliadas macroscopicamente e por microscopia eletrônica de varredura. Adicionalmente, foi realizado ensaio de compressão para determinar a força necessária para fraturar os implantes. Após a evisceração do olho esquerdo, nove coelhos da raça Nova Zelândia receberam implantes de poliamida e nove outros receberam implantes de ABS. Os animais foram avaliados diariamente nos primeiros 15 dias após a cirurgia e a cada sete dias até o fim do período experimental (90 dias). Avaliação histopatológica foi realizada aos 15, 45 e 90 dias após a cirurgia. Os implantes de ABS pesaram 0,44g, e os de poliamida 0,61g. A microscopia eletrônica de varredura demonstrou que os implantes de ABS eram formados por microporos equidistantes, enquanto os de poliamida apresentavam microporos de vários tamanhos. A força necessária para fraturar os implantes de ABS foi de 14.39±0.60 Mpa, enquanto para os de poliamida foi de 16.80±1.05Mpa. Quinze dias após a cirurgia, foi observada infiltração fibrovascular centrípeta. Os implantes podem ser utilizados para correção de cavidades anoftálmicas por se mostrarem inertes, biocompatíveis e permitirem a infiltração tecidual.(AU)

Evaluation of intraorbital prosthetic pigmentation using 0.3 and 1.5 Tesla magnetic resonance imaging and computed tomography.

PURPOSE: To investigate the magnetic susceptibility artifact associated with pigmented intraorbital prosthetics when performing magnetic resonance imaging (MRI) and computed tomography (CT). Potential artifact reduction techniques were also investigated. STUDY DESIGN: Prospective study. METHODS: Five different-colored 20-millimeter small animal silicone intraorbital prosthetics and two equine prosthetics were evaluated using 0.3 and 1.5 Tesla (T) MRI and CT. MRI sequences included T1- (T1WI) and T2-weighted spin echo (T2WI), T2 gradient echo (T2*), short tau inversion recovery (STIR), and fluid-attenuated inversion recovery (FLAIR). When present, artifact size was measured using computerized software by three separate observers. Artifact reduction techniques included alterations in receiver bandwidth, field of view, slice thickness, and matrix size. RESULTS: The ferrous brown-pigmented prosthetic resulted in a magnetic susceptibility artifact with MRI. No artifact was observed on CT images. Interobserver variability was not statistically significant. For both the 0.3T and 1.5T MRI, the T2* sequence exhibited the largest artifact surface area followed by T2WI, T1WI, STIR, and FLAIR. Decreasing slice thickness showed a decrease in artifact size; however, this difference was not statistically significant. CONCLUSIONS: The ferrous substances in the brown intraorbital prosthetic resulted in a significant magnetic susceptibility artifact when performing MRI. Artifact reduction techniques did not significantly decrease artifact surface area. The use of ferrous brown-pigmented prosthetics and their potential to affect future MR imaging studies should be adequately discussed with pet owners.

Magnetic resonance imaging susceptibility artifact due to pigmented intraorbital silicone prosthesis.

Magnetic resonance imaging (MRI) findings of two cases with intracranial disease and pigmented intraorbital prosthetics are presented. A brown prosthetic (Case 1) caused a significant magnetic susceptibility artifact, which necessitated removal to properly image the brain. The artifact observed on MRI images is likely due to ferromagnetic pigments used for coloring. A black prosthetic (Case 2) caused no imaging artifact. The carbon-based pigments used to color the black prosthetic implant do not appear to cause imaging artifact. The pigments currently used to color the brown pigmented orbital prostheses cause significant magnetic susceptibility artifact and may require removal to evaluate the brain and surrounding structures completely.

Comparison of orbital prosthesis motility following enucleation or evisceration with sclerotomy with or without a motility coupling post in dogs.

OBJECTIVE: To evaluate motility of silicone orbital implants and corneoscleral prostheses, with and without use of a motility coupling post (MCP) in dogs. ANIMALS STUDIED: Eighteen mixed-breed dogs. PROCEDURES: The motility of an orbital silicone implant and corneoscleral prosthesis after enucleation (n = 6), evisceration (n = 6), or use of a MCP with evisceration (n = 6) in dogs were compared. One eye from each dog had surgery whereas the opposite eye was used as a control. Clinical evaluations were performed three times a week. Histopathology of the orbital tissues was performed 8 and 12 weeks after surgery. RESULTS: Implant motility in dogs with evisceration (vertical movement [VM] 8.04 +/- 2.13; horizontal movement [HM] 11 +/- 3.05) and evisceration with MCP (VM 9.61 +/- 1.59); HM was significantly greater than the enucleation group (VM 0.51 +/- 0.5; HM 1.22 +/- 0.68) (P < 0.01). Prosthetic motility in dogs with evisceration with MCP was significantly greater than in dogs with evisceration; dogs with evisceration had significantly greater motility than dogs with enucleation (P < 0.01). No postoperative complications were observed in any of the groups. No significant abnormalities were noted on histopathology. CONCLUSIONS: MCP placement in silicone orbital implants significantly enhanced the prosthetic motility in dogs. This study supports the use of MCP in silicone orbital implants to enhance corneoscleral prosthesis motility and cosmetics in dogs.

Surgery of the globe and orbit.

Orbital anatomy and the indications and surgical techniques for a variety of small animal orbital/globe surgical procedures are discussed. Details of the more common orbital surgical procedures, including ocular evisceration, intrascleral prosthesis implantation, enucleation, and proptosis repair, are given. Common complications and postoperative considerations for these procedures are also discussed with an emphasis on the practical aspects.

Surgical outcome and ocular complications of evisceration and intraocular prosthesis implantation in dogs with end stage glaucoma: a review of 20 cases.

Surgical outcome and complications following evisceration and implantation of intraocular silicone prosthesis (ISP) in 20 canine eyes with end-stage glaucoma were analyzed, including clinical signs, complications, cosmetic appearance, and owners' responses. The mean postoperative follow-up time was 312 days. Major short-term surgical complications were central corneal ulceration (6/20) and infections (3/20), while long-term complication was keratoconjunctivitis sicca (KCS) (2/20). All patient owners (100%) showed satisfied with the surgical outcome and postoperative cosmetic effect including 85% of the owners gave an excellent or good rating of satisfaction. No more medication needed for long term control except the KCS cases. With careful case selection and post-operative care, evisceration with ISP implantation proves a good and safe surgical procedure with minimal complications for end stage glaucoma.

Cosmetic globe surgery in the horse.

Effects of traumatic injury or inflammation on the equine eye can be catastrophic. These ocular conditions can frequently result in blindness or chronic pain. In addition to blindness and pain, permanent unsightly cosmetic defects can occur. This article addresses options available for improved cosmetic outcome in horses with ocular scars or requiring enucleation. Many of these options have been described in detail previously. New information has been added to the discussion of each option where pertinent.

Use of a hydroxyapatite orbital implant in a cosmetic corneoscleral prosthesis after enucleation in a horse.

A hydroxyapatite orbital implant was used after enucleation of an eye from a 5-year-old performance horse. A custom-made corneoscleral prosthesis was made and fitted over the hydroxyapatite implant. The implant and surgery were well tolerated. Placement of a cosmetic prosthesis is desired after enucleation of equine eyes to allow horses to return to competition. Synthetic spheres consisting of methylmethacrylate or silicone have been used, although reported complications have included extrusion, infection, and poor cosmetic results. Hydroxyapatite orbital implants made from marine coral allow vascular and fibrous tissue growth from the host orbit into the implant, which decreases the possibility of implant extrusion or infection and allows enhanced healing of defects in the overlying conjunctiva. Extraocular muscle fixation onto the implant permits motility and assists in the prevention of implant extrusion.

Orbital exenteration and placement of a prosthesis in fish.

OBJECTIVE: To develop a procedure for orbital exenteration and prosthesis placement in fish. DESIGN: Prospective study. ANIMALS: 5 cultured hybrid striped bass (Morone saxatilis x M chrysops) ranging from 30 to 50 cm in length. PROCEDURE: Exenteration was performed, using a dorsal approach in which blunt dissection was performed in the circumorbital sulcus. The orbit was then dried, and simple interrupted sutures were placed, leaving 2 suture loops within the orbit. The orbit was filled with polyvinylsiloxane, and a prosthetic glass eye was seated in the polyvinylsiloxane. RESULTS: All fish retained the prosthesis and had satisfactory cosmetic results at the end of the 8-week study period. CLINICAL IMPLICATIONS: The increase in popularity of pet fish and abundance of valuable aquarium and show fish have led to heightened awareness of piscine ocular disease. Aquarium fish are often euthanatized because of disfiguring ocular problems. The technique described here for surgical exenteration and cosmetic orbital prosthesis placement in fish may extend the captive life of public display fish.

[Intascleral silicone prosthesis in the dog: a retrospective study of 22 cases]. / Intrasklerale Silikonprothesen beim Hund: eine retrospektive Studie von 22 Fällen.

Over a period of five years 28 dog eyes were treated by evisceration and implantation of an intrascleral silicone prosthesis. During an average follow-up period of 2.93 years the only complication noted was a mild entropion in one case. The majority of dog owners were satisfied with the cosmetic result. All of them would again opt for this procedure and prefer it to an enucleation. The postoperative management was well tolerated by both animals and owners. After careful preoperative work-up and ruling-out of intraocular neoplasms, evisceration/prosthesis is a simple and practical method to salvage buphthalmic eyes and globes with beginning phthisis bulbi. Intraocular tumors and septic endophthalmitis are the two principal contraindications. In addition, eyes with deep or even perforated corneal ulcers should not be fitted with an intrascleral prosthesis.

A new type of intraocular prosthesis for dogs.

A simple technique is described in which sterile silicone oil (viscosity 350 cSt) was injected into the globe of an eviscerated eye with an intact cornea and sclera; the volume injected was calculated from the formula 3/4 pi r3 where 'r' was the horizontal corneal diameter. After induction of general anaesthesia and routine preparation of the surgical site, the globe was eviscerated by using a transscleral or transcorneal approach. The procedure was carried out in five dogs with follow-ups ranging between 19 and 27 months. None of the eyes developed postoperative complications. In one dog, more silicone oil had to be injected 10 days after surgery to increase the size of the globe to match the other eye. The intraocular contents were removed more easily by using the transcorneal approach, which also resulted in a perfect adjustment and virtually eliminated the possibility of leakage of silicone oil, than by a transscleral approach. The dogs responded extremely well and their owners were satisfied with the cosmetic appearance of their pets.

The surgical repair of the cornea of the dog using pericardium as a Keratoprosthesis

A substituiçäo da córnea em lesöes oculares tem merecido a atençäo dos oftalmologistas, sendo que vários materiais têm sido usados para este fim. O pericárdio de equino, conservado em glicerina, foi usado no reparo de lesöes penetrantes de córnea de dois cäes, um pela excisäo de melanoma límbico, outro pela presença de estafiloma periférico. Cäo, Pastor Alemäo, com 6 anos de idade, apresentando massa de 1 cm de diâmetro, localizada na regiäo temporal do limbo esclero-corneano do olho direito, com 2 meses de evoluçäo e cäo de 4 meses, mestiço, que teve ferida sua córnea esquerda com prolapso de íris, em consequência de arranhadura de gato, 5 dias antes, foram examinados no Serviço de Oftalmologia do Hospital Veterinário da Faculdade de Medicina Veterinária e Zootecnica da Universidade de Säo Paulo. As lesöes de ambos os animais foram reparadas com fragmento de pericárdio de equino para fechamento do defeito produzido. Aplicaçäo de pomada antibiótica e colírio de atropina de 1 por cento foi instituída no pós-operatório. A pressäo intra-ocular foi baixa nos primeiros dias subsequentes à cirurgia, mas foi gradativamente aumentando chegando a valores normais. Inicialmente, tecido de granulaçäo foi observado próximo ao implante, e opacificaçäo do pericárdio permaneceu. Colírio de dexametasona foi entäo indicado, sendo que o tecido de granulaçäo desapareceu dois meses após a cirurgia. A câmara anterior permaneceu profunda durante toda a evoluçäo. O acompanhamento pós-operatório mostrou os olhos em boas condiçöes após dezoito meses

Use of orbital implants after enucleation in dogs, horses, and cats: 161 cases (1980-1990).

Eye enucleations performed on 109 dogs, 29 horses, and 23 cats involved placement of 136 silicone orbital implants and 7 mesh implants. Mean follow-up times were 2.4 years (range, 3 weeks to 9 years) in dogs, 3.4 years (range, 10 days to 10.5 years) in horses, and 1.5 years (range, 3 weeks to 7.5 years) in cats. Implants failed in 1 of 96 dogs (1.04%), 3 of 29 horses (10.3%), and 3 of 18 cats (16.7%). Implant failure was attributable to various causes in all species; however, cats appeared to be more prone to late extrusion that were dogs and horses. Implantation of an orbital prosthesis was a safe and inexpensive method for improving cosmetic appearance after enucleation in dogs, horses, and cats.

Ocular cosmetic and prosthetic devices.

Specific details on surgical procedures, although not covered here, are available in other references. Factors enhancing the overall cosmetic appearance obtained with procedures are emphasized, providing information that should allow veterinarians to offer clients a good cosmetic appearance and effective treatment for disfiguring ocular problems in their horses. Questions regarding procedures should be addressed to your referral ophthalmologist or, in the case of a corneoscleral prosthesis, the ocularist assisting.

Intraocular silicone prostheses in a dog and a horse with corneal lacerations.

Intraocular silicone prostheses were implanted in the eyes of a horse and a dog with traumatic corneal lacerations and protrusion of intraocular contents. Several months after surgery, the horse and dog were tolerating the intraocular prostheses, and the appearance was cosmetically acceptable. This contradicts earlier reports that have cited corneal disease as a contraindication for implantation of intraocular silicone prostheses.

Silicone ocular prosthesis in horses: 11 cases (1983-1987).

Horses experience a number of ophthalmic diseases and injuries that may result in loss of function of the eye. In the treatment of end-stage ophthalmic disease or injury that precludes salvage of the eye, the use of an inert, silicone prosthetic implant is a cosmetic alternative to simple enucleation. Eleven horses treated either by enucleation and insertion of an intraorbital prosthesis (n = 9) or by evisceration and insertion of an intraocular prosthesis (n = 2) were evaluated for postoperative complications and for long-term cosmetic results. Of the 11 horses treated, complication rate was low; during hospitalization, 1 horse with an intraorbital implant developed a localized incisional infection that resolved in response to antimicrobial therapy. Nine horses were available for follow-up evaluation. Cosmetic appearance was rated as excellent in 5 horses and good in 4 horses. Insertion of an intraocular implant had the best cosmetic result. Complications were not reported by any owner or caretaker. Routine use of intraorbital and intraocular implants is encouraged because of their modest cost and ease of insertion.

Intraocular silicone prosthesis in a horse.

A 40-mm intraocular silicone prosthesis was placed in a horse's globe to control glaucoma. The glaucoma was suspected to be associated with a lens subluxation, but primary glaucoma could not be ruled out. Medical treatment and cyclocryotherapy had been attempted, but failed to decrease the intraocular pressure to a normal value. The prosthesis was placed, via a dorsal scleral incision, after removal of the intraocular contents. The size of the prosthesis was estimated from measurements of the horse's normal left globe and an enucleated, age-matched globe. Silicone prostheses offer a cosmetic alternative to enucleation of blind, sensitive globes in horses.