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PubMed1999

Effect of diode laser trans-scleral cyclophotocoagulation in the management of glaucoma after intravitreal silicone oil injection for complicated retinal detachments.

AIMS: To evaluate the effect of trans scleral cyclophotocoagulation (TSCPC) on intraocular pressure (IOP) in the eyes retaining intravitreal silicone oil with medically uncontrolled secondary glaucoma following intravitreal silicone oil injection. METHODS: Medical records of 11 eyes of 11 patients who underwent TSCPC for medically uncontrolled glaucoma without pupillary block following intravitreal silicone oil injection for complicated retinal detachment were reviewed retrospectively. In all cases, intravitreal silicone oil was not removed for fear of retinal redetachment. Diode laser contact TSCPC was performed at a power of 1.5-2.5 W, for a duration of 2 seconds, and with 20-27 applications. IOP, number of glaucoma medications, and success rate were evaluated. RESULTS: After a mean follow up period of 52.5 (SD 8.2) (range 42-68) weeks, the mean pretreatment level of IOP, 43.0 (14.4) (26-67) mmHg, had fallen to 14.5 (4.3) (7-20) mm Hg (p=0.003). The number of glaucoma medications was reduced from 2.6 (0.8) to 0.6 (1.0) (p= 0.005). Qualified success was achieved in nine eyes (81.8%) and complete success in six (54.5%). After TSCPC, patients' retinal status had not changed. CONCLUSION: Patients with medically uncontrolled glaucoma secondary to intravitreal silicone oil injection can be treated with TSCPC in spite of the retained intravitreal silicone oil.

Adult↗
PubMed2001

Combined phacoemulsification and transpupillary drainage of silicone oil: results and complications.

AIM: To review retrospectively 74 consecutive cases of combined phacoemulsification and transpupillary drainage of silicone oil. METHODS: Candidate patients for intraocular silicone oil removal and cataract extraction underwent combined phacoemulsification and transpupillary drainage of silicone oil through a planned posterior capsulorrhexis and without the use of a pars plana infusion line. RESULTS: The retina remained attached in 59 (79.7%) patients postoperatively. In this success group, the postoperative visual acuity improved in 42 (71.2%) patients. There was no association between age, duration of silicone oil tamponade, preoperative diagnosis, macular status or number and nature of previous surgery, and the incidence of redetachment following silicone oil removal. CONCLUSION: Combined phacoemulsification and transpupillary drainage of silicone oil is a safe and reliable technique that offers the main advantage of diminished surgical trauma.

Adolescent↗
PubMed1999

Contrast medium-induced pulmonary edema is aggravated by silicone contamination in rats.

PURPOSE: To examine the effect of silicone contamination, which occurs in clinical settings during vial preparation with disposable syringes, on contrast medium-induced pulmonary edema in rats. MATERIALS AND METHODS: Ioxaglate, ioversol, and iohexol, silicone-containing physiologic saline solutions, and three silicone-containing contrast media were separately, intravenously injected at 1.5 mL/min in rats. Pulmonary edema was evaluated as changes in the relative lung weight and in the water, sodium, and potassium contents of the lung. RESULTS: Intravenous injection of ioxaglate induced marked pulmonary edema, even with a dose of only 4 g of iodine per kilogram of body weight. In contrast, ioversol and iohexol induced significant pulmonary edema only after the injection of large doses (6 g of iodine per kilogram; P < .05). The injection of 4 microL/mL silicone-containing physiologic saline at a dose of 18.75 mL/kg also produced marked pulmonary edema, whereas doses of 6.25 and 12.5 mL/kg showed no significant influence. The addition of an ineffective dose (12.5 mL of physiologic saline per kilogram of body weight) of silicone in contrast medium substantially aggravated the pulmonary edema induced by the contrast medium alone; this phenomenon was also confirmed with morphologic observation. CONCLUSION: Ionic contrast media are more toxic to the endothelial cells than are nonionic contrast media. Silicone contamination might be one of the causes of pulmonary edema after intravenous injection. However, caution must be exercised in extrapolating these results to humans.

Animals↗
PubMedDate not supplied

Long-term vitreous replacement with perfluorohexyloctane and silicone oil: preliminary reports of a multicentric study.

AIM: To report on the use of a combined intra-ocular tamponade with silicone oil and perfluorohexyloctane (F(6)H(8)) in the treatment of complex retinal detachment. DESIGN: A prospective consecutive interventional case series from seven study centres. PARTICIPANTS: 69 patients presenting a retinal detachment with proliferative vitreoretinopathy (PVR) and retinal breaks of the inferior two quadrants of the fundus. METHOD: Patients were divided into two groups: (1) 28 eyes which had not been operated on before; (2) 41 eyes affected by recurrent retinal detachment that had had unsuccessful previous surgery with silicone oil or gas tamponade. A pars plana vitrectomy, membrane peeling and -- when necessary -- a retinotomy were performed; the vitreous cavity was filled with two thirds of F(6)H(8) and one third of silicone oil 1,000 mPas (double filling, DF). The endotamponade was removed after 30-45 days (median 38) and replaced by balanced salt solution or silicone oil according to the condition of the retina. RESULTS: Retinal reattachment was achieved in 52 out of 69 cases (75%) 6 months after removal of the DF without any endotamponade. CONCLUSION: The DF with F(6)H(8) and silicone oil allows a good endotamponading to the inferior retina and the posterior pole. The DF appeared to be well tolerated. Further studies are necessary to evaluate whether a DF is advantageous in respect to silicone oil filling alone in case of retinal breaks and PVR of the inferior retina.

Adult↗
PubMed1979

Adult rabbit eye and orbital volumes after periodic intrabulbar injections of silicone.

The intent of this experiment was to determine whether periodic injections of silicone into the adult rabbit eye would alter the volume of the eye and/or orbit. This procedure in growing rabbits had resulted in increased volumes of both the eye and orbit. Nineteen 13-month-old (adult) rabbits were used. In 12 animals silicone was injected into one eye but not the opposite one. No silicone was injected into the eyes of 7 untreated rabbits. In a 9-week period the total amount of ten silicone injections into each treated eye ranged from 5.7 to 7.6 ml. 1 week after the last injection each eye was enucleated, an impression made immediately, and a permanent model subsequently developed. From this the volume was determined. A t test was performed on the mean differences of the eye and orbital volumes of the injected and noninjected sides for each group. No significant differences was found. It was concluded within the limitations of this experiment that there was no evidence that periodic intrabulbar injection of silicone into the adult rabbit eye altered its volume. Thus, this procedure also did not alter orbital volume. In contrast, in the growing rabbit both eye and orbital volume had increased significantly after intrabulbar injection of silicone.

Animals↗
PubMed1997

Contrast sensitivity in patients with silicone intraocular lenses.

Contrast sensitivity in 64 patients aged from 50 to 69 years with an intraocular lens (IOL) was studied. There were 23 eyes with a silicone and 31 eyes with a polymethylmethacrylate (PMMA) IOL. Ten patients had a silicone IOL in one eye and a PMMA IOL in the other. Contrast sensitivity was examined with the Vistech far vision VCTS 6500 test. The contrast sensitivity test results in silicone and PMMA IOL eyes were in all cpd (cycles per degree) lines significantly worse than in normal eyes except in the 60-year-old group in the 18-cpd line. The contrast sensitivity test results were in all cpd lines better in the silicone IOL eyes than in the PMMA IOL eyes, but it reached significantly only in the 3-cpd line. In the 10 patients with the silicone lens in one and the PMMA lens in the other eye, the test results were also better in the silicone IOL eye; it also reached significance only in the 3-cpd line.

Aged↗
PubMed1995

Silicone breast implants and autoimmunity: causation, association, or myth?

In vivo and in vitro studies, case reports and population studies show that: (1) silicone is immunogenic; (2) silicone is biodegradable and transported via the reticuloendothelial system to distant locations; (3) silicone breast implants "leak" and in turn silicone migrates outside the breast tissue; (4) case reports and population studies document an autoimmune reaction and immunological dysfunction in patients with silicone breast implants; (5) these immunological abnormalities and symptoms are reversible upon removal of the breast implants (in 50-70% of cases). The criteria to establish medical causation are defined, and based on those criteria it is concluded that silicone breast implants cause immunological disease.

Animals↗
PubMed1995

Rheumatic disorders in patients with silicone implants: a critical review.

More than 1000 patients with rheumatic disorders and silicone implants have been reported. In this review, the clinical features of patients with scleroderma, inflammatory myositis, systemic lupus erythematosus and silicone implants are discussed. The clinical features of the most common rheumatic disorder associated with silicone implants, the "Silicone Implant Associated Syndrome", are introduced. In addition, other local regional, and neurologic disorders associated with silicone implants are discussed. This comprehensive clinical review provides the clinician with information regarding the common symptoms, signs and laboratory features of rheumatic disorders of patients with silicone implants.

Arthritis, Rheumatoid↗
PubMed1995

Surface modification of silicone for percutaneous implantation.

In order to prevent epidermal down growth when a silicone percutaneous device was implanted, immobilization of collagen was performed onto the surface of a silicone device. The immobilization of collagen was achieved through covalent bonds between the amino groups in the collagen molecules and the carboxyl groups in poly (acrylic acid) chains grafted onto the silicone device surface. When the collagen-immobilized silicone device model was percutaneously implanted in rabbits, no sign of epidermal down growth was observed even 7 weeks after implantation, while the epidermis reached down to the deep part of the dermis as early as 3 weeks after implantation when collagen was not immobilized onto the device model surface. To have tighter fixation of the device models to the surrounding dermal tissue, the silicone device model was covered with a polyethylene sponge having an average interconnecting pore size of 150 microns. Collagen immobilization was also performed onto the sponge surface. Both the collagen-immobilized silicone device models as well as the non-treated models with polyethylene sponge were percutaneously implanted in rabbits and epidermal down growth as well as the occurrence of bacterial infection was examined. Without collagen immobilization onto the sponge surface of the device model, bacterial infection was noticed as early as 2 weeks after the implantation. The number of infected device models increased as the implantation time became longer and bacterial infection was observed in six out of seven device models at the 10th week post implantation. When the sponge surface was immobilized with collagen, bacterial infection was noticed in only one model at the 5th week after implantation. Six out of seven implanted device models with collagen immobilization were free of bacterial infection until the animals were sacrificed 30 weeks after implantation.

Animals↗
PubMed2001

A first step in prediction of the nanoscale structure of porous silicon from processing parameters.

The present work addresses the formation of porous silicon layers by means of anodic dissolution of p- and p(+)-type boron-doped (100) silicon wafers in 15, 25, and 35 vol% HF-ethanol solutions. The study concerned the dependence of the porous silicon layer growth rate dh/dt on electric current density i as well as on HF concentration. The formation of a porous silicon layer was found to follow a generic linear relationship, in(dh/dt)--in(i), which holds irrespective of the processing conditions. The combination of two equations, experimental and theoretical, derived from Faraday's equation, allowed us to reach conclusions on the relationship between the growth rate dh/dt and the degree of porosity, constituting a first step in prediction of the nanoporous structure of silicon based on processing parameters. This electrochemical approach complements physical models of silicon pore formation.

Computer Simulation↗
PubMedDate not supplied

Risk factors for anatomical success and visual outcome in patients undergoing silicone oil removal.

PURPOSE: To define risk factors for anatomical success and visual outcome in patients undergoing removal of silicone oil. METHODS: This retrospective study included patients who had silicone oil removed at this hospital between 1996 and 2000. All were followed for at least six months. Patients with recurrent retinal detachment after silicone oil removal were compared with patients without this complication. We also compared patients whose vision improved or stabilized with patients whose vision deteriorated. Risk factors for anatomical success and visual outcome were identified. RESULTS: We analysed 94 eyes of 92 patients with silicone oil removal. Nineteen eyes (20%) had recurrent retinal detachment, and in 30 eyes (32%), the vision deteriorated after removal of the oil. Initial vision less than ambulatory vision, initial pathology of giant retinal tears and recurrent retinal detachment, postoperative hypotony and postoperative epiretinal membrane occurred more frequently in eyes with than without recurrent retinal detachment. Pre- and postoperative hypotony, postoperative epiretinal membranes and postoperative recurrent retinal detachment were also more frequent in eyes with deteriorated vision. CONCLUSIONS: When treating giant retinal tears or recurrent retinal detachments with silicone oil tamponade, surgeons and their patients need to be aware of the higher possibility of unfavorable results, particularly when the initial vision is less than ambulatory vision. The presence of risk factors before and after silicone oil removal should remind surgeons of the higher risk profile of this particular surgery.

Adolescent↗
PubMedDate not supplied

Intraoperative biometry for intraocular lens (IOL) power calculation at silicone oil removal.

PURPOSE: Cataract development is common following retinal detachment surgery that necessitates silicone oil injection. Intraocular lens (IOL) power calculation in the presence of silicone oil is challenging for many reasons. The authors evaluated the accuracy of intraoperative biometry during cataract surgery in silicone-filled eyes. METHODS: Twelve cases of cataract in eyes filled with silicone oil after retinal detachment surgery were included. Preoperatively, keratometric readings were documented. Intraoperative axial length was measured following removal of silicone oil using a sterile probe of the Nidek Echoscan US800 unit. IOL power calculation was computed using the SRK/T formula. This was followed by phacoemulsification and foldable lens implantation. Postoperative refraction allowed evaluation of the accuracy of intraoperative biometry. The predictability of three different formulas was also compared (Holladay, SRK/T, and SRK II). RESULTS: Seven men and five women with a mean age of 50.2 years were included in the study. The mean postoperative spherical equivalent using the described technique was 6.77 +/- 0.43 diopters. SRK/T and Holladay formula had the best predictability for high axial length eyes, whereas the three studied formulas showed no significant differences in predictability in eyes with normal axial length. CONCLUSIONS: Intraoperative biometry proved to have good predictability for the absolute postoperative refractive error in cataract surgery for eyes at the time of silicone oil removal. This predictability was accurate independent of axial length.

Adult↗
PubMed1994

Acute pneumonitis after subcutaneous injections of silicone for augmentation mammaplasty.

In a period of 3 years, seven cases of acute pneumonitis have been found after patients have been subcutaneously injected with silicone for the sole purpose of augmentation mammaplasty. Adverse symptoms following these silicone injections were fever, hypoxemia, hemoptysis, and abnormal diffuse bilateral alveolar infiltrates in both lungs. Pulmonary hemorrhaging occurred, and this was substantiated by using the bronchoscope with the bronchoalveolar lavage (BAL). The alveolar macrophage obtained from the BAL contained large quantities of pleomorphic cytoplasmic particles, which in actual fact were silicone particles. They were identified as silicone by scanning electron microscopy and energy-dispersive analysis of x-rays. This evidently showed that silicone diffusion into the circulatory system and subsequent embolization of the lung. Pulmonary function studies had shown restrictive changes with increase or normal single-breath carbon monoxide diffusing capacity (Dsb). Perfusion lung scans were interpreted as showing diffuse abnormalities consisting of decreased peripheral uptake. Acute hypoxemic respiratory failure was noted in four of these patients. Silicone injections of this nature were therefore a respiratory risk and caused the inducement of pneumonitis.

Acute Disease↗
PubMed1996

Silicone stents in the management of benign tracheobronchial stenoses. Tolerance and early results in 63 patients.

STUDY OBJECTIVE: To assess tolerance and early results of Dumon silicone stents inserted in patients with nonneoplastic airway obstruction. DESIGN: Tracheobronchial stenting for palliative or curative restoration of airway narrowing has been evaluated in a retrospective study. SETTING: Tertiary-referral teaching hospital. PATIENTS: Between May 1991 and September 1994, 64 patients with a mean age of 52 years had endobronchial silicone stent insertion for benign tracheal stenosis (82% secondary to intubation or tracheostomy injury). Lesions were pure fibrous stenosis in 25 patients and fibroinflammatory stenosis in 38. Prostheses were used for temporary stenting of the airway during 18 months in 48 patients in whom cure was expected and as a procedure for palliation in the remaining 15 patients. INTERVENTIONS: In all cases, the Dumon tracheobronchial stent was implanted with the rigid bronchoscope under general anesthesia. RESULTS: Five patients died (four from unrelated causes); one was due to hypersecretion and airway obstruction at the time of an emergency tracheostomy 20 days after stent insertion. Complications included migration of prostheses in 11 (17.5%) patients, granuloma formation in 4 (6.3%) patients, and airway obstruction due to heavy secretion in 4 (6.3%). In 48 patients who received silicone stents with curative expectations, removal of the device was accomplished in 21 patients. Therapy proved successful in 17 patients with a mean follow-up of 259+/- 173 days and stenosis recurred in 4. In 16 patients, stents still remain for a mean period of 364+/-119 days. In the series of 15 patients in whom silicon stents were implanted for palliation, prostheses were placed permanently in 11 with a mean follow-up of 486+/-260 days. In the remaining four patients with tracheostomy, silicone stents were used after inability to expand the upper limb of the T-tube (two patients) or placed above the tracheostomy stoma to maintain laryngotracheal patency and preserve phonation when a T-tube was poorly tolerated (two patients). CONCLUSIONS: Silicone tracheobronchial stents are effective in the maintenance of airway patency and are associated with good tolerance and infrequent complications that are rarely life-threatening.

Adolescent↗
PubMed2003

Adjustable silicone gastric banding adverse events reported to the Food and Drug Administration.

A silicone adjustable gastric banding system was approved by the Food and Drug Administration (FDA) in June, 2001. The purpose of this report is to review and characterize the reports on silicone adjustable gastric banding systems received by the FDA through August 8, 2002. We also review medical literature on adverse events with silicone adjustable gastric banding systems. Manufacturers of regulated medical devices, such as adjustable silicone gastric bands, are required to report adverse events, including deaths and serious injuries, to the FDA. We reviewed all such reports received by the FDA through August 8, 2002, for adjustable silicone gastric bands and summarize the data by type of adverse event, reported device problems, and reported patient problems. The FDA received 556 reports of adverse events related to the use of adjustable silicone gastric bands. Two of these reports were for deaths, one during surgery and the other as a result of an erosion of the gastric band into the stomach 9 weeks after implantation. Forty-four reports were for injuries including band erosions, slippage, and infection. The most common type of report (499) was for device malfunction, and of these, 485 (97.2%) described a leak at or near the port. Of the 485 leaks reported as malfunctions, 99.4% were treated surgically. The majority of reports were related to disconnection, breakage, and leakage at or near the access port. Physicians and potential patients should be aware of these problems and recognize the possibility that additional surgery(ies) may be required for leaking access port/connections. The loose connection may cause pain and the device no longer performs as intended when there is a leak.

Female↗
PubMed2005

Treatment of acne scars with liquid silicone injections: 30-year perspective.

BACKGROUND: This article addresses the use of liquid injectable silicone as both an immediate and long-lasting treatment for broad-based, depressed acne scars. The only filler substance that maintains precision and permanence in improving and/or correcting these types of acne scar defects is medical-grade liquid silicone. OBJECTIVE: We describe five patients with a history of acne scarring who showed improvements from injections of liquid silicone at the initial treatment session and lasting over a 10-, 15-, and 30-year follow-up period. METHODS: Monthly liquid silicone injections using a technique known as the microdroplet, multiple-injection approach. RESULTS: This article documents the safety, effectiveness, and precision of silicone in addition to highlighting the fact that its permanence is what distinguishes it from other filler materials. CONCLUSION: As a precise and permanent filling substance used for soft tissue augmentation, liquid injectable silicone can improve and/or eliminate depressed, broad-based acne scars through a technique known as the microdroplet, multiple-injection

Acne Vulgaris↗
PubMed2005

Effect of a silicone-containing dressing on exuberant granulation tissue formation and wound repair in horses.

OBJECTIVE: To determine the effect of a silicone dressing on the rate and quality of repair of limb wounds and compare microvascular occlusion and apoptosis in wounds treated with the silicone dressing and those treated with a conventional dressing in horses. ANIMALS: 5 horses. PROCEDURE: Horses received two 6.25-cm2 wounds on each metacarpus. Ten wounds were treated with a silicone dressing; the other 10 were treated with a control dressing. Quality of repair and wound size were evaluated at each bandage change. Time to healing and the number of excisions of exuberant granulation tissue were recorded. Biopsy specimens taken from healed wounds were evaluated semiquantitatively via histologic examination, p53 immunohistochemical analysis, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) to quantify apoptosis, and electron microscopic examination to measure microvessel luminal diameters. RESULTS: The silicone dressing surpassed the conventional dressing in preventing formation of exuberant granulation tissue and improving tissue quality. Microvessels were occluded significantly more often in wounds dressed with the silicone gel, which also diminished the expression of mutant p53, an indirect inhibitor of apoptosis, although greater apoptosis was not confirmed quantitatively by use of TUNEL. CONCLUSIONS AND CLINICAL RELEVANCE: Because the silicone dressing inhibited the formation of exuberant granulation tissue, it may be integrated in a management strategy designed to improve the repair of limb wounds in horses.

Animals↗
PubMed1995

Lack of lymph node reaction to subcutaneously injected silicone gel: histological and computer aided morphometric study in rats.

The gel of silicone implants may bleed through the elastomeric envelope or may come into contact with the body because of rupture of the implant. We have studied the effects of free silicone gel injected into the subcutaneous space in rats and analysed the morphological features of the axillary and inguinal lymph nodes. Ninety six Wistar rats had 3 cm3 of silicone gel injected into their subcutaneous space and 96 Wistar rats (the control group) had distilled water injected into their subcutaneous space. The animals were killed on days 1,3,7,9,15, 30,60,90,120,180,270, and 365 after the injection. There was no detectable silicone and no damage to the lymph nodes on routine histopathological analysis. Small amounts of silicone that could migrate to lymph nodes could result in hyperplasia. To evaluate this possibility, a morphometric study based on a computer aided system compared the area of lymph node sections between treated and control animals, and showed no difference between treated and control groups. If silicone did migrate, it did not provoke morphological signs or hyperplasia in the lymph nodes.

Animals↗