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Breast implant-related silicone granulomas: the literature and the litigation.

Formation of a granuloma is a common tissue response to the presence of a variety of foreign materials. A silicone granuloma is, by definition, a type of tissue reaction elicited occasionally by silicone. Granulomas of this sort have not engendered a great deal of attention in the scientific literature since their first description in 1964, and they were considered by most surgeons through the 1980s to be an incidental finding of little or no consequence. Since it is tangible and readily visible to juries, the silicone granuloma became a frequent issue in breast implant litigation in the 1990s. Although most other complaints in this litigation have been subjective or causally unrelated to silicone, the presence of a granuloma has been used as a basis of local complication claims and, more creatively, as a mechanism for hypothetical systemic disease occurrence. This review examines the basic science and the clinical literature pertaining to breast implant-related silicone granulomas, viewing them in a context of current clinical thought and frequent issues of litigation. Clinically apparent silicone granulomas are a relatively rare complication of breast implant placement and surgical resection is indicated when they are symptomatic or of diagnostic concern. There is no evidence in the peer-reviewed scientific literature to support frequent plaintiff theories in litigation that silicone granulomas play some role in implant-related systemic disease. In fact, the very existence of such diseases, themselves, is equally unsubstantiated.

Breast Implants↗

Experimental retinal tolerance to emulsified silicone oil.

Vitreous replacement by silicone oil has become increasingly popular in the treatment of severe and complicated retinal detachment. Several studies have suggested that silicone oil may be toxic to the retina or may stimulate periretinal proliferation. To better understand its effects, emulsified or nonemulsified silicone oil was injected into rabbit eyes that had undergone mechanical vitrectomy. Silicone oil was labeled with phthalocyanine blue to aid in histologic localization. Retinal changes were compared by light microscopy at 1, 4, and 12 weeks after intraocular injection. Emulsified silicone oil was found to penetrate the inner retina at 1 week and cause epiretinal membrane formation as early as 4 weeks after injection. Nonemulsified oil produced no histologic changes in the retina. No cytotoxic effects were observed in eyes treated with ether emulsified or nonemulsified silicone oil. It is concluded that emulsified silicone oil can both penetrate the retina and stimulate epiretinal membrane formation in the vitrectomized rabbit eye.

Animals↗

Silicone oil removal combined with macular pucker dissection: a retrospective review of 14 cases.

PURPOSE: Silicone oil must be removed from the eye to avoid late complications after the surgical management of proliferative vitreoretinopathy (PVR). Macular pucker, frequently observed after retinal detachment surgery, is responsible for visual impairment. The safety of a procedure combining epimacular membrane peeling and silicone oil removal was retrospectively evaluated. METHODS: Fourteen eyes that had previously undergone vitrectomy and silicone oil tamponade for rhegmatogenous retinal detachment with severe PVR, penetrating or blunt trauma, and intraocular foreign bodies were included. Silicone oil tamponade was maintained for a mean period of 30 weeks (range, 12-108 weeks). The removal of silicone oil was combined with the peeling of an epimacular membrane. RESULTS: Mean follow-up after silicone oil removal was 86 weeks (range, 13-234 weeks). The final retinal reattachment rate was 78%. Macular pucker recurred in one eye after a 24-month period. Best-corrected visual acuity improved two lines or more in eight eyes (57%) and reached 20/200 or better in eight eyes (57%) at last follow-up. CONCLUSION: Macular pucker dissection and silicone oil removal can be safely combined. This single procedure can obviate the need for further surgery in eyes that have already undergone multiple operations and allows good visual recovery.

Adolescent↗

Ultrasound biomicroscopy in silicone oil-filled eyes.

PURPOSE: To establish reproducible ultrasound biomicroscopy (UBM) imaging patterns characteristic of the presence and behavior of silicone oil and of peripheral vitreoretinal proliferation in eyes that have undergone vitreoretinal surgery with silicone oil injection. METHODS: The study design was a case series. Ultrasound biomicroscopy was performed on 34 eyes of 34 patients (age range, 20-68 years). For an image to be considered a UBM pattern, it was required to be consistently reproducible in the same eye and to be observed in more than one eye. RESULTS: Four patterns are described: silicone oil particles, ghost images, "painting" or surface impregnation of iris and anterior chamber angle, and peripheral proliferative vitreoretinopathy. One type of ghost image, the secondary reflection of the cornea, paired with disappearance of the aqueous-silicone oil interface corresponded to massive silicone oil displacement into the anterior chamber. Gross proliferation produced funnel and tentlike images, whereas minute, networklike images seemed to represent early changes. There was a close correspondence between these UBM patterns and previous ophthalmologic clinical findings. CONCLUSION: Easily recognizable, distinct UBM patterns are characteristic of conditions found in silicone oil-filled eyes. Ultrasound biomicroscopy seems to be a useful tool for assessing changes in silicone oil-filled eyes.

Adolescent↗

Management of recurrent retinal detachment in silicone oil-filled eyes.

PURPOSE: To report causes of failure, management options, and outcomes after reoperations for recurrent retinal detachment in silicone oil-filled eyes. METHODS: One hundred eighteen silicone oil-filled eyes with recurrent retinal detachment were managed with revision of vitrectomy with membrane surgery with or without silicone oil removal, just scleral buckling, or both. Anatomical success was defined as complete reattachment of the retina, and functional success was defined as recovery of ambulatory visual acuity of >or=5/200 at the last follow-up (mean follow-up, 29.7 months). RESULTS: In 82.2% of the cases, proliferative vitreoretinopathy was responsible for recurrent retinal detachment in silicone oil-filled eyes. Reoperations without removal of the silicone oil were performed in 65.3% of the cases. Anatomical success occurred in 62.7% of the eyes, and functional success occurred in 52.5%. Silicone oil was removed in 59.5% of the eyes with retinal reattachment; the retina remained attached in 90.9% of the eyes. Predictors of poor anatomical success were presence of posterior diffuse proliferative vitreoretinopathy and combined posterior and anterior proliferative vitreoretinopathy (P <0.02). CONCLUSION: Reoperations for recurrent retinal detachment in silicone oil-filled eyes were successful in nearly two thirds of the cases, and over one half of the eyes recovered ambulatory vision.

Adolescent↗

The problems of biometry in combined silicone oil removal and cataract extraction: a clinical trial.

PURPOSE: To evaluate the problems and accuracy of biometry in eyes that have been operated on by silicone oil removal combined with cataract extraction with or without intraocular lens implantation. SUBJECTS AND METHODS: Twenty-nine consecutive cases that have been operated on for silicone oil removal and cataract, with or without intraocular lens implantation, were included in a prospective study. Axial length measurement was done in silicone oil-filled eyes after changing the sound speed in vitreous cavity to 987 m/sec. The SRKT formula was used for intraocular lens calculation. The cataract was removed by phacoemulsification through corneal section or phacofragmentation through the standard vitrectomy sclerotomy. Intraocular lens implantation was done either on the peripheral anterior capsule (single piece, PMMA) or in the bag (acrylic foldable three pieces). The final refraction after at least 3 months' follow-up was measured. The difference between the predicted and the actual refraction was evaluated. A control group of 30 consecutive cases (20 nonmyopic and 10 highly myopic) of cataract extraction and intraocular lens implantation in eyes not filled with silicone oil was included using the same evaluation methods. RESULTS: The mean deviation of the final from the predicted refraction was 1.87 +/- 2.11 diopters (range, +3.25 to -9 diopters). A total of 72.4% had a deviation of +/-2 diopters. The mean deviation in high myopia was 3.04 +/- 2.68 diopters (12 cases) (range, +/-1.75 to -9 diopters), while in nonmyopic patients, the mean deviation was 1.04 +/- 1.04 diopters (17 cases) (range, +3.25 to -3.25 diopters). The difference between highly myopic and nonmyopic eyes was statistically significant (P < 0.05). Most high errors occurred in highly myopic eyes. There was no statistical difference between the types of silicone oil (1000 versus 5000) or the mode of cataract extraction (phacoemulsification versus pars plana phacofragmentation). In the control group, the mean deviation in high myopia was 1.48 +/- 1.02 diopters (10 cases) (range, +/-0.5 to -3.5 diopters), while in nonmyopic patients, the mean deviation was 0.65 +/- 0.75 diopters (20 cases) (range, +2.75 to -1.75 diopters). The difference was statistically significant (P < 0.05). CONCLUSION: Intraocular lens calculation in silicone oil-filled eyes is accurate in eyes that are not highly myopic. Some highly myopic eyes with posterior staphyloma have great deviation. Unsuitable formula, artifacts, or large eyes beyond the machine range may be the cause of errors of deviation of refraction. Comparable results are obtained in eyes regardless of the type of silicone oil (1000 or 5000) and techniques of intraocular lens implantation (in the sulcus or in the bag).

Adult↗

Fourier transform infrared and 1h nuclear magnetic resonance spectroscopic findings of silicone oil removed from eyes and the relationship of emulsification with retinotomy and glaucoma.

PURPOSE: To investigate whether structural changes occur in silicone oil that has been left in the eye for different periods and to research the relationship of emulsification with the time during which silicone oil is left in the eye, glaucoma, and wide relaxing retinotomy. METHODS: Samples of silicone oil were randomly removed from the eyes of 22 patients. Gel permeation chromatography (GPC) and spectroscopy were used to identify any changes in the silicone oil. The relationship between spectroscopically determined emulsification with time spent in the eye, glaucoma, and wide relaxing retinotomy was investigated statistically. RESULTS: GPC revealed that no change was found in the 1,000-centistoke silicone oil model after it had been removed from the eye. Spectroscopy identified absorption peaks belonging to water in addition to those belonging to the functional groups. The relationships between emulsification and time spent in the eye and glaucoma were found to be statistically insignificant, while that between emulsification and wide relaxing retinotomy was statistically significant. CONCLUSION: Intravitreally applied silicone oil undergoes no structural change. Wide relaxing retinotomy constitutes a risk factor for silicone oil emulsification, which can occur earlier than expected and before it can be observed clinically.

Adolescent↗

Comparison of silicone and polypropylene Ahmed Glaucoma Valve implants.

PURPOSE: To compare the efficacy and safety of silicone and polypropylene Ahmed Glaucoma Valves (AGVs) in patients with refractory glaucoma. METHODS: A retrospective chart review of 180 eyes of 166 patients who underwent AGV implantation with a minimum follow-up period of 3 months was performed. All patients who underwent implantation of either the AGV model S-2 (polypropylene) or model FP-7 (silicone) were included, unless previous laser cyclophotocoagulation had been performed. The primary outcome measures were the change in intraocular pressure (IOP) and visual acuity after surgery and the rate of postoperative complications. RESULTS: No significant differences were seen in the baseline characteristics of patients in each group. Baseline IOP was statistically equivalent in the 2 groups (silicone =33.8+/-11.9 mm Hg, polypropylene=33.0+/-10.3 mm Hg, P=0.6). A significant reduction in IOP from baseline was achieved after both silicone and polypropylene AGV implantation (silicone =-17.7+/-11.8 mm Hg, polypropylene =-17.7+/-11.3 mm Hg, both P<0.00005). However, there was no statistically significant difference in IOP decrease between the 2 groups at any follow-up visit (all P>0.09). The mean number of postoperative antiglaucoma medications was also similar in the silicone and the polypropylene AGV groups at each time point (all P>0.2). The rate of complications and the change in visual acuity did not differ between the 2 groups (P>0.6 and P>0.3, respectively). CONCLUSIONS: Silicone and polypropylene AGVs have similar results with respect to both safety and efficacy in the treatment of patients with refractory glaucoma.

Antihypertensive Agents↗

Untreated silicone breast implant rupture.

Implant rupture is a well-known complication of breast implant surgery that can pass unnoticed by both patient and physician. To date, no prospective study has addressed the possible health implications of silicone breast implant rupture. The aim of the present study was to evaluate whether untreated ruptures are associated with changes over time in magnetic resonance imaging findings, serologic markers, or self-reported breast symptoms. A baseline magnetic resonance imaging examination was performed in 1999 on 271 women who were randomly chosen from a larger cohort of women having cosmetic breast implants for a median period of 12 years (range, 3 to 25 years). A follow-up magnetic resonance imaging examination was carried out in 2001, excluding women who underwent explantation in the period between the two magnetic resonance imaging examinations (n = 44). On the basis of these examinations, the authors identified 64 women who had at least one ruptured implant at the first magnetic resonance imaging examination and, for comparison, all women who had intact implants at both examinations (n = 98). Magnetic resonance images from the two examinations were compared and changes in rupture configuration were evaluated. Comparisons were also made for self-reported breast symptoms occurring during the study period and for changes in serum values of antinuclear antibodies, rheumatoid factor, and cardiolipin antibodies immunoglobulin G and immunoglobulin M. The majority of the women with implant rupture had no visible magnetic resonance imaging changes of their ruptured implants. For 11 implants (11 percent) in 10 women, the authors observed progression of silicone seepage, either as a conversion from intracapsular into extracapsular rupture (n = 7), as progression of extra-capsular silicone (n = 3), or as increasing herniation of the silicone within the fibrous capsule (n = 1); however, in most cases, these changes were minor. Some changes could be ascribed to trauma, but others seemed spontaneous. There was no increase in levels of autoantibodies during the study period in either study group. Women with untreated implant ruptures reported a significant increase in nonspecific breast changes (odds ratio, 2.1; 95 percent confidence interval, 1.2 to 3.8) compared with women without ruptures. On the basis of this first study of women with untreated silicone breast implant rupture, the authors conclude that implant rupture is a relatively harmless condition, which only rarely progresses and gives rise to notable symptoms. Even so, because of a small risk of silicone spread, the authors suggest that women with implant ruptures be followed clinically, if not operated on. Because implant ruptures often occur asymptomatically, any woman with silicone implants, regardless of rupture status, should be evaluated at regular intervals.

Adult↗

Salvage of silicone-treated facial deformities using autogenous free tissue transfer.

BACKGROUND: Silicone, in the form of injectable liquid and prosthetic blocks, has been used to correct facial contour defects. However, silicone also has been associated with many complications including malposition, dyschromia, dysesthesia, contractures, infection, and fistula. Complications related to injectable-liquid and prosthetic-block silicone use in treatment of facial deformities pose a challenging surgical dilemma. METHODS: Over a 15-year period, microvascular free flap technique has been used successfully as a surgical tool to correct severe soft-tissue complications of the face resulting from silicone treatment of facial contour deformities. Surgical treatment guidelines, methods, and results for treating this difficult problem with free tissue transfer are presented. RESULTS: In 23 patients, 24 free tissue transfers (22 inframammary extended circumflex scapular free flaps and two superficial inferior epigastric free flaps) were performed. Flap survival was 100 percent. Both hematoma and skin necrosis were encountered in three of 24 cases (12.5 percent). Revisional surgery combined with aesthetic surgical procedures was required in 20 of 24 cases (83 percent). CONCLUSIONS: We recommend the following surgical treatment guidelines for this unique subset of patients: silicone excision with immediate microvascular free flap reconstructive procedure when the skin and soft tissue are mildly to moderately affected, or silicone excision with delayed reconstructive procedure when the skin and soft tissue are severely affected. Free tissue transfer is a useful surgical tool for salvaging severe facial skin and soft-tissue deformities caused by previous silicone treatment.

Adipose Tissue↗

Dwell time and functional failure in percutaneous endoscopic gastrostomy tubes: a prospective randomized-controlled comparison between silicon polymer and polyurethane percutaneous endoscopic gastrostomy tubes.

BACKGROUND: Silicone percutaneous endoscopic gastros-tomy (PEG) tubes are associated with more short-term complications and possibly fail sooner than those made of polyurethane. Understanding the deterioration and long-term complications leading to tube failure has important clinical and cost implications. AIM: To compare dwell time and patterns of failure ofsilicone polymer and polyurethane PEG tubes. METHODS: Participants randomized to receive a siliconepolymer (n = 76) or polyurethane (n = 62) PEG werevisited monthly for 540 days, until death or tube removal. Tube and exit site characteristics and reasons for removal were recorded. RESULTS: Tube failure occurred in 25% of silicone PEGs and 12.9% of polyurethane PEGs. Mean tube survival for silicone PEGs was 377.2 days (CI: 326-428) and for polyurethane 436.8 days (CI: 383-490; P = 0.13). A greater proportion of silicone PEGs developed intralumenal colonization and altered tube integrity than polyurethane (P < 0.001). Silicone PEGs blocked more frequently (P < 0.005) and were removed because of irreversible blockage more often than polyurethane PEGs (P < 0.05). Silicone PEGs with reversible blockage and tube integrity changes had a significantly greater probability of failure than silicone tubes without these changes (P < 0.005 and P < 0.05, respectively). CONCLUSIONS: Observations over time indicate that sili-cone PEGs are more susceptible than polyurethane PEGs to tube deterioration, resulting in substantially increased management demands to sustain patients' feeding and medication schedules.

Adult↗

Self-assembly and recrystallization of bacterial S-layer proteins at silicon supports imaged in real time by atomic force microscopy.

The self-assembly of bacterial surface-layer (S-layer) proteins (SbpA of Bacillus sphaericus CCM 2177) at silicon supports (hydrophobic, non-plasma-treated and hydrophilic, O2 plasma-treated silicon supports) was imaged in real time by atomic force microscopy (AFM). A closed mosaic layer consisting of small crystals (less than 200 nm in diameter) was formed at a hydrophobic silicon support, whereas a coherent crystalline lattice consisting of large domains (2-10 micro m in size) was generated at O2 plasma-treated, hydrophilic silicon wafers. The structure of the formed layers was a monolayer (9 nm in height) at the hydrophobic silicon and a bilayer (15 nm in height) at the hydrophilic silicon. In situ AFM measurements confirmed the importance of ionic bonds in the formation of crystalline SbpA layers at silicon supports. Rupture of the protein subunits with a metal chelator from the crystalline lattice of SbpA was visualized in situ by AFM. The stability of solid-supported SbpA layers could be enhanced by cross-linking the S-layers with amino-amino or amino-carboxyl group directed cross-linkers.

Bacillus↗

Vitamin E added silicone gel sheets for treatment of hypertrophic scars and keloids.

BACKGROUND: Trauma of various origins can induce a connective tissue disorder that leads to keloids. This condition has yet not been clearly distinguished from scars and hypertrophic scars. Only electronmicroscopic and biochemical data can help to do this. Among some more or less therapeutic approaches, the use of silicon (polydimethylsiloxane) plates, wrapped on the keloid surface, has been reported effective by some authors. These authors also demonstrated that it is not the mechanical pressure that is the mechanism of action, but a direct action on fibroblasts and a hyperhydration of subcutaneous tissue. The authors of this study conceived that the silicon plate may be able to improve the transdermal penetration of a compound such as vitamin E. This vitamin is capable of preserving some important morphologic and functional features of biological membranes by means of its phytilside chain of the molecule acting as a stabilizer of lysosomal membranes. MATERIALS AND METHODS: Eighty patients of both sexes, aged between 18 and 63 years, who had hypertrophic scars and keloids, were admitted to the trial. The patients were randomized to two groups in a simple-blinded study. Group A: Forty patients whose scars have been covered with silicon plates with added vitamin E. Group B: Forty patients treated with simple silicone gel sheets. No pressure bandages were used, only tape fixing the sheet for 10 hours overnight. The trial lasted for 2 months. The results were recorded at 4 and 8 weeks, evaluating the improvement according to a Scott-Husskinson scale. For objective assessment photos were taken. The results were analyzed by the chi-square test. RESULTS: At the end of the first month, group A had improved by more than 50% in 85% of cases, whereas the improvement in group B was 55% (P < 0.01). At the end of the second month, 95% of patients in group A had improved by 50%, whereas 75% had improved by 50% in group B (P < 0.05). CONCLUSIONS: Vitamin E added to the silicon plate scored better than the simple silicon plate at the end of both periods. We have reported the successful combined action of vitamin E and silicone gel sheets in scar treatment, especially in the short-term prophylaxis of hypertrophic scars or keloids.

Administration, Topical↗

Comparative histopathology of epidural hydrogel and silicone elastomer catheters following 30 and 180 days implant in the ewe.

New catheter materials, termed Hydrogels, have been developed recently that are stiff until exposed to hydration. The purpose of this study was to compare the 30 and 180 day histopathology of catheters composed of a common silicone elastomer versus a Hydrogel elastomer blend (HEB). Epidural catheters composed of either silicone or HEB were implanted in 19 yearling ewes for either 30 or 180 days. The degree of fibrotic reaction in the epidural space, muscle and subcutaneous tissue was assessed using both histopathology and quantitative imaging analysis. A separate subset of three ewes were implanted with HEB epidural catheters connected to subcutaneously implanted ports through which twice weekly injections of saline were given. There was no evidence of significant neurotoxicology associated with either the silicone or the HEB catheter materials. However, the silicone elastomer group had a quantifiably greater degree of fibrosis than the HEB group of both implant durations. The mean cross sectional area (sq. mm) of epidural pericatheter fibrosis was significantly smaller in the HEB group compared with the silicone group (0.491 in the HEB group and 1.585 in the silicone group at 30 days [P = 0.02] and 0.28 and 1.401 at 180 days [P = 0.0001]. The HEB catheter was easily inserted with standard epidural needles facilitated by the inherent stiffness of the catheter prior to hydration. HEB catheters remained patent throughout 30 days of saline injections per implanted ports. Silicone catheters demonstrated increased fibrosis relative to the HEB catheter material in the epidural space and in subcutaneous tissue.

Anesthesia, Epidural↗

Augmentation mammoplasty and "silicone-osis".

BACKGROUND: Claims have been made that breast augmentation induces a previously unrecognized disease ("silicone-osis"). AIMS: To confirm the existence of "silicone-osis", qualify and quantify its characteristics. METHODS: In this population-based retrospective cohort study, the health status of 458 female Sydney residents who had augmentation mammoplasty for cosmetic reasons ("augmentation mammoplasty-exposed" or "exposed" cohort) between 1979 and 1983 was compared with the health status of 687 female Sydney residents who had non-silicone-associated plastic surgery ("augmentation mammoplasty-nonexposed" or "non-exposed" cohort). Both groups were matched for age (+/- 5 years), year of plastic surgery (+/- 2 years), plastic surgeon, anaesthetist and mode of anaesthesia. Outcome measures comprised dummy symptoms to assess reporting bias, as well as symptoms and symptom clusters from a comprehensive 78-symptom list. RESULTS: Dummy variables were not over-reported by the exposed cohort. The following individual symptoms developed more commonly in the exposed cohort after index plastic surgery: "memory loss/confusion", "altered bowel habit", "chest pain made worse by deep breathing", "shortness of breath after walking up 10 steps", "breast pain", "sweating mainly at night" and "tunnel vision". Of eight identified symptom clusters, three were rejected as biologically unimportant: "joint swelling of the bunion joint", "haemorrhoids" and "breast lumps" (the latter two occurring more commonly in the non-exposed cohort). In contrast, five symptom clusters were thought to have potential biological importance and occurred more commonly in the exposed cohort. The symptom "night sweats" was common to all five clusters, and comprised the sole symptom in one instance. The other four multisymptom clusters were also characterized by "low energy" (lethargy) and "pins and needles", whereas "breast pain", "impaired memory", "muscle pain" and "reflux", occurred in three of the four clusters. CONCLUSION: Cluster analysis suggested the existence of a multisystem disorder occurring more commonly in the exposed cohort and characterized by night sweats, lethargy, breast pain, impaired mentation, reflux, paraesthesiae, hand muscle weakness and myalgia. The argument against this being a new disease entity --"silicone-osis"-- however, was its presence, albeit at lower frequency, in the silicone-unexposed cohort. Thus this study did not confirm the existence of a new disease entity "silicone-osis" uniquely and causally associated with silicone exposure. The possible interpretations of these findings are discussed.

Autoimmune Diseases↗

Lack of protective effects of dietary silicon on aluminium-induced maternal and developmental toxicity in mice.

In recent years, it has been demonstrated that oral aluminium (Al) exposure can produce growth retardation, delayed ossification and an increased incidence of foetal abnormalities in rats and mice. On the other hand, it has been also suggested that silicon may have a protective effect in limiting oral Al absorption. The aim of the present study was to assess whether dietary silicon could prevent against Al-induced maternal and developmental toxicity in mice. On gestation days 6-15, Al nitrate nonahydrate (398 mg/kg/day) was given by gavage to three groups of pregnant animals, which also received silicon in drinking water at concentrations of 0, 118 and 236 mg/l on days 7-18 of gestation. Three additional groups of pregnant mice received respectively: 270.6 mg/kg of sodium nitrate (gavage), and silicon in drinking water at 118 and 236 mg/l. Although silicon administration at 236 mg/l significantly reduced the percentage of Al-induced deaths, abortions and early deliveries, neither 118 nor 236 mg/l of silicon produced significant ameliorations on Al-induced foetotoxicity. Under the current experimental conditions dietary silicon was not effective in protecting against Al-induced developmental toxicity.

Abnormalities, Drug-Induced↗

Changes in corneal endothelium after treatment of retinal detachment with intraocular silicone oil.

Keratopathy represents one of the most frequent late complications in eyes with complicated retinal detachment treated with intraocular silicone oil. Corneal examinations including endothelial specular photography were done on 18 silicone treated eyes, 16 of which were aphakic. In addition to widespread silicone oil endothelial contact in 2 eyes, a bubble or droplets of silicone oil were observed in the anterior chamber in 8 eyes. The mean endothelial cell density was lower in the silicone eyes (2076 +/- 196 cells/mm2) as compared to the control fellow eyes (2738 +/- 86 cells/mm2) (P = 0.004). In eyes with silicone oil in the anterior chamber the endothelial cell density was significantly decreased (1857 +/- 232 cells/mm2) (P = 0.005). Obvious endothelial degeneration was noticed when silicone oil had been in the eye for more than a year. Also small droplets of oil with transient contact contributed to its development.

Adolescent↗

Deposition of silicone oil droplets in the residual anterior lens capsule after vitrectomy and lensectomy in rabbits.

AIM: To examine the histology of preserved anterior lens capsule in vitrectomised and lensectomised rabbit eyes with and without silicone oil tamponade. METHODS: Forty adult Japanese albino rabbits received two port vitrectomy and lensectomy with or without silicone oil tamponade in one eye under both general and topical anaesthesia. Anterior lens capsule was preserved during operation. After healing intervals residual anterior capsule was histologically observed under light or electron microscopy. RESULTS: Immediately after operation, cuboidal lens epithelial cells were observed on the posterior surface of the preserved anterior capsule. During healing intervals in eyes with or without silicone oil tamponade, regenerated lens structure of Sommerring's ring and fibrous tissue formed in the peripheral and central areas of the residual capsule, respectively. Ultrastructural observation revealed the presence of many vacuoles amid matrix accumulation on the posterior capsular surface, suggesting the deposition of emulsified silicone oil droplets. CONCLUSION: Lens epithelial cells produce regenerated lenticular structure and fibrous tissue on the residual capsule following vitrectomy and lensectomy in rabbits. Silicone oil droplets formed by its emulsification deposit in extracellular matrix accumulated on the posterior surface of the anterior capsule. Emulsified silicone may potentially enhance opacification of residual anterior capsule following pars plana vitrectomy by silicone oil deposition and subsequent activation of lens epithelial cells.

Animals↗