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PubMed2005

In vitro haemocompatibility and stability of two types of heparin-immobilized silicon surfaces.

Heparin was covalently immobilized onto a silicon surface by two different methods, carbodiimide-based immobilization and photo-immobilization. In the former method, a (3-aminopropyl) trimethoxysilane (APTMS) self-assembled monolayer (SAM) or multilayer was first coated onto the silicon surface as the bridging layer, and heparin was then attached to the surface in the presence of water-soluble carbodiimide. In the latter method, an octadecyltrichlorosilane (OTS) SAM was coated on the silicon surface as the bridging layer, and heparin was modified by attaching photosensitive aryl azide groups. Upon UV illumination, the modified heparin was then covalently immobilized onto the surface. The hydrophilicity of the silicon surface changed after each coating step, and heparin aggregates on APTMS SAM and OTS SAM were observed by atomic force microscopy (AFM). In vitro haemocompatibility assays demonstrated that the deposition of APTMS SAM, APTMS multilayer and OTS SAM enhanced the silicon's haemocompatibility, which was further enhanced by the heparin immobilization. There is no evident distinction regarding the haemocompatibility between the heparin-immobilized surfaces by both methods. However, heparin on silicon with APTMS SAM and multilayer as the bridging layers is very unstable when tested in vitro with a saline solution at 37 degrees C, due to the instability of APTMS SAM and multilayer on silicon. Meanwhile, photo-immobilized heparin on silicon with OTS SAM as the bridging layer showed superb stability.

Animals↗
PubMed2005

Attachment of Acanthamoeba to first- and second-generation silicone hydrogel contact lenses.

PURPOSE: To investigate the attachment of Acanthamoeba to first- and second-generation silicone hydrogel contact lenses, and to determine if patient wear or the presence of a bacterial biofilm coating affects attachment characteristics. DESIGN: Experimental study. PARTICIPANTS AND CONTROLS: Attachment to the silicone hydrogel lenses was compared with that to a conventional hydrogel control lens. Sixteen replicates (n = 16) were carried out for unworn, worn, and biofilm-coated lenses of each type. METHODS: Unworn, worn, and Pseudomonas aeruginosa biofilm-coated first-generation (lotrafilcon A) and second-generation (galyfilcon A) silicone hydrogel and conventional hydrogel (etafilcon A) lens quarters were incubated for 90 minutes in suspensions of plate-cultured Acanthamoeba castellanii trophozoites. MAIN OUTCOME MEASURES: Trophozoites attached to one surface of each lens quarter were counted by direct light microscopy. Logarithmic transformation of data allowed the use of parametric analysis of variance for statistical analysis. RESULTS: Attachment of Acanthamoeba was affected significantly by lens material type (P<0.001), with higher numbers of trophozoites attaching to the first-generation lotrafilcon A silicone hydrogel lens, compared with the second-generation galyfilcon A lens and the conventional hydrogel lens. Attachments to the latter 2 lenses did not differ significantly from each other (P = 0.126). Patient wear and the presence of a bacterial biofilm had no significant effect on attachment to the lotrafilcon A lens (P = 0.426) but did significantly increase attachment to the galyfilcon A (P<0.001) and the etafilcon A (P = 0.009) lenses; attachment to the latter 2 lenses was still significantly less than that found with the first-generation silicone hydrogel (P<0.001). CONCLUSIONS: Acanthamoeba demonstrated a significantly greater affinity for the first-generation silicone hydrogel lens as compared with the second-generation silicone hydrogel and the conventional hydrogel. If exposed to Acanthamoeba (e.g., when showering or swimming, through noncontinuous wear and ineffective lens care regimes), first-generation silicone hydrogel lenses may promote a greater risk of Acanthamoeba infection due to the enhanced attachment characteristics of this lens material. However, prospective studies in patients are required to determine if these experimental results are clinically significant.

Acanthamoeba castellanii↗
PubMed2006

Comparison of polypropylene and silicone Ahmed Glaucoma Valves.

PURPOSE: To evaluate and compare the clinical outcomes after implantation of the silicone plate and the polypropylene plate Ahmed Glaucoma Valves. DESIGN: Prospective, multicenter, comparative series. METHODS: A total of 132 patients with uncontrolled glaucoma were treated with either the silicone or polypropylene Ahmed Glaucoma Valve implant. MAIN OUTCOME MEASURES: Success was defined according to 2 criteria: (1) intraocular pressure (IOP) of 6 mmHg or more or 21 mmHg or less, and (2) IOP reduction of at least 30% relative to preoperative values. Eyes requiring further glaucoma surgery, including cyclophotocoagulation, or showing loss of light perception were classified as failures. RESULTS: Average follow-up was 12.8 months (range, 6-30 months) for the silicone plate group and 14.5 months (range, 6-30 months) for the polypropylene plate group (P = 0.063). At the last follow-up examination, the mean IOP was 13.8+/-3.9 mmHg and 17.3+/-6.5 mmHg (P<0.0001) and the mean number of antiglaucoma medications was 1.9+/-1.3 and 2.1+/-1.4 (P = 0.48) in the silicone plate and polypropylene plate groups, respectively. The life-table success rates for the silicone plate and polypropylene plate groups were 94.2% and 83.2% at 12 months and 82.4% and 56.7% at 24 months by definition 1, respectively (P = 0.035). When an IOP reduction of at least 30% was used for success criterion (definition 2), probabilities of success were 89.5% and 71.7% at 12 months and 78.3% and 68.5% at 24 months in the silicone and the polypropylene plate groups, respectively (P = 0.012). Visual outcomes were comparable between the 2 groups. However, complications including Tenon's cyst were observed more frequently in the polypropylene plate than in the silicone plate group (P<0.05). CONCLUSIONS: The silicone Ahmed Glaucoma Valve (model FP7) showed improved IOP reduction compared with the polypropylene (model S2) implant. Differences observed in mean IOP, success rate, and complications suggest that plate material may influence clinical outcome.

Adult↗
PubMed2004

Silicone oil in the subarachnoidal space--a possible route to the brain?

Using this case report, we sought evidence that silicone oil may infiltrate the subarachnoidal space. Vitrectomy combined with silicone oil implantation was performed on the right eye of a 72-year-old woman. The silicone oil was removed 2 months later, because the patient had developed elevated intraocular pressure. The blind and painful eye was subsequently enucleated. By light microscopy, presumed silicone oil bubbles were identified in the optic nerve and the subarachnoidal space of the enucleated eye. These vacuoles were examined by energy-dispersive X-ray analysis (EDAX). In addition, in the vacuoles, immunohistochemistry was used to test for the presence of CD 68-positive macrophages. Silicone oil infiltration sites in the optic nerve, in the central retinal artery, and in the subarachnoidal space were located by light microscopy and confirmed by EDAX. CD 68-positive macrophages were found in the silicone-filled vacuoles. Silicone oil used for endotamponade may infiltrate the optic nerve and even the subarachnoidal space. This supports the assumption that silicone oil, under special circumstances, may even migrate into the brain.

Aged↗
PubMed1999

Association of silicone breast implants with immunologic abnormalities: a prospective study.

PURPOSE: To study the possible association of silicone-breast-implant exposure and immunologic abnormalities within the Nurses' Health Study, an ongoing prospective cohort study of women. SUBJECTS AND METHODS: From this cohort, we randomly selected 200 women who had been exposed to silicone breast implants and who had never reported connective tissue diseases during 14 years of follow-up, and 500 age-matched, nonexposed women, including 100 with definite connective tissue diseases validated by medical record review, 100 with at least one symptom of a connective tissue disease, 100 with diabetes, and 200 healthy controls. Assays for antinuclear antibodies (ANA), including anti-dsDNA, anti-ssDNA, anti-Sm/RNP/Ro/La, and anti-Scl-70, rheumatoid factor, immunoglobulins, serum complement, and C-reactive protein level, and anticardiolipin, antithyroglobulin, antithyroid microsomal, and antisilicone antibodies were performed by standard techniques in blood samples collected in 1989 or 1990 before collection of silicone-breast-implant exposure data in 1992. RESULTS: ANA was positive (> or = 1:40) in 14% of women with silicone breast implants compared with 20% of healthy women (P = 0.11). Rheumatoid factor was positive (> or = 1:40) in 5% of women with silicone breast implants and 2% of healthy women (P = 0.16). Women with silicone breast implants had a significantly higher frequency of anti-ssDNA antibodies than healthy women (41% and 29%, P = 0.012). Duration of implant was associated with a higher frequency of anti-ssDNA antibodies (P = 0.03) but not with ANA or rheumatoid factor. No other significant differences in the frequencies of autoantibodies were observed in silicone breast implant-exposed women. Antisilicone antibodies were not found in any sample. CONCLUSION: We found no increased frequency of any immunologic abnormalities in women exposed to silicone breast implants, except for anti-ssDNA, which has unknown clinical relevance.

Adult↗
PubMed2001

Silicone oil-associated optic nerve degeneration.

PURPOSE: To report the frequency and extent of silicone oil migration into the optic nerve during silicone oil endotamponade. METHODS: Histopathologic analysis of 74 eyes enucleated after silicone oil endotamponade. RESULTS: In 14 of 74 enucleated eyes (24%), optically empty vacuoles regarded as silicone oil vacuoles were observed in the retrolaminar optic nerve. In three eyes, silicone oil in the optic nerve was surrounded by a granulomatous inflammatory reaction. In serial cross sections, the vacuoles extended up to the line of surgical transsection (up to 9 mm) of the optic nerve and constituted up to 40% of the total cross-sectional area. CONCLUSIONS: After silicone oil endotamponade, silicone oil may replace a considerable amount of tissue of the retrolaminar optic nerve. A granulomatous inflammatory reaction surrounding silicone oil may add to optic nerve damage.

Eye Enucleation↗
PubMed2003

Intraretinal silicone oil vacuoles after macular hole surgery with internal limiting membrane peeling.

PURPOSE: To report the detection of intraretinal silicone oil vacuoles after the use of a silicone oil tamponade for macular hole surgery with internal limiting membrane (ILM) peeling. DESIGN: Observational case report. METHODS: A 57-year-old woman with a recurrent macular hole in the left eye underwent macular hole surgery with ILM peeling and silicone oil tamponade. After early silicone oil emulsification was detected, the silicone oil was removed. RESULTS: Follow-up ophthalmoscopic examination and optical coherence tomography imaging revealed intraretinal silicone oil vacuoles in the area of ILM peeling. CONCLUSIONS: Internal limiting membrane defects may facilitate the entry of silicone oil into the retina, leading to accumulation of oil vacuoles. The use of silicone oil in macular hole surgery with ILM peeling may complicate the postoperative outcome.

Basement Membrane↗
PubMed2000

Posterior capsular opacification with hydrogel, polymethylmethacrylate, and silicone intraocular lenses: two-year results of a randomized prospective trial.

PURPOSE: To compare the visual outcome, percentage of posterior capsular opacification, and laser capsulotomy rates with polymethylmethacrylate, silicone, and hydrogel intraocular lens implants at 1 and 2 years postoperatively. METHODS: Ninety-three eyes of 93 patients were randomized to receive a polymethylmethacrylate, silicone, or hydrogel intraocular lens implant. A standardized surgical protocol was followed by a single surgeon using phacoemulsification with capsulorhexis; any patients with surgical complications were excluded, and all patients received standardized medication and follow-up. Patients were examined at days 1 and 7, months 1, 3, and 6, and years 1 and 2 after surgery. At each assessment, best-corrected logMAR visual acuity and Pelli-Robson contrast sensitivity were measured. Posterior capsular opacification was objectively assessed by digital retroillumination imaging with the use of a dedicated software program and calculated as the percentage area of opacified capsule. Laser capsulotomy was performed if the eye had lost 2 lines of visual acuity with a clinically opaque capsule. RESULTS: At 2 years postoperatively, the mean percentage area of posterior capsular opacification for hydrogel lenses was 63%; for polymethylmethacrylate, 46%; and for silicone, 17%. Hydrogel intraocular lenses were associated with 17% more posterior capsule opacification than were polymethylmethacrylate lenses (95% confidence interval, 1-33; P =. 037) and 45% more than were silicone lenses (95% confidence interval, 33-58; P <.0001) at 2 years. Polymethylmethacrylate lenses had 28% more posterior capsule opacification than silicone lenses (95% confidence interval, 13-43; P <.0001) at 2 years. Twenty-eight percent of patients with hydrogel intraocular lenses required an Nd:YAG laser posterior capsulotomy at 2 years, compared with 14% with polymethylmethacrylate, whereas no patients with silicone lenses needed a capsulotomy (P =.014). Visual acuity was not significantly different among the three groups, but patients with silicone intraocular lenses had significantly better contrast sensitivity than those with hydrogel lenses (P =.046). CONCLUSIONS: Intraocular lenses made of this specific hydrogel were associated with a significantly higher degree of posterior capsular opacification and more laser capsulotomies than polymethylmethacrylate and silicone intraocular lenses.

Aged↗
PubMed1993

Silicone shedding from artificial urinary sphincter in children.

Silicone is an inert material used in all genitourinary prosthetic devices. Silicone particle shedding has been documented in adults with penile prostheses and artificial urinary sphincters. We searched prospectively for silicone particles in the peri-prosthetic tissue and regional lymph nodes in 6 children who underwent removal or exchange of an artificial urinary sphincter. The peri-prosthetic fibrous capsule was biopsied and examined by light and polarizing microscopy. Regional lymph nodes were biopsied if clinically enlarged and evaluated in a similar manner. Lymph nodes from 2 children without an artificial urinary sphincter served as controls. An artificial urinary sphincter was in place from 3 to 10 years (mean 4.3 years) and none of the sphincters demonstrated infection or erosion. Silicone particles were found in the peri-sphincteric tissue of 3 patients, which induced foreign body giant cell reaction in 2 and eosinophilic infiltrate in 1. Focal histiocytic proliferation around the cuff was seen in another case without silicone migration. There was fibrosis around the sphincter in all cases. No silicone was found in the regional lymph nodes. Silicone shedding was documented in 50% of our patients. X-ray energy dispersive spectroscopy was not performed, raising the possibility that it was under-detected. Long-term effects of silicone in children with an artificial urinary sphincter are unknown and warrant further study.

Child↗
PubMed2002

Silicon excretion from bioactive glass implanted in rabbit bone.

Bioactive glass granules were implanted in the tibiae of rabbits in order to determine the pathway of the silicon released from bioactive glass in vivo. We traced and quantified the silicon released by obtaining 24-h urine samples and blood samples for up to 7 months after implantation. Bone tissue as well as the following organs were resected for chemical and histopathological analyses: kidney, liver, lung, lymph nodes, and spleen. The urinary silicon of the implanted group was significantly higher than in the control group. From the data, the calculated average excretion rate was approximately 1.8 mg/day, and as such, the amount of implanted silicon was excreted within statistical bounds in 24 weeks. At this point, only elevated concentrations of silicon were found at the implant site and not in the other organs. The concentrations of silicon measured in the urine were well below saturation. Since no significant increase in silicon was found in any of the organs including the kidney, the increased silicon excretion rate was within the physiological capacity of rabbits. Therefore, it can be concluded that the resorbed silica gel is harmlessly excreted in soluble form through the urine.

Animals↗
PubMed1999

Enhanced proliferation and osteocalcin production by human osteoblast-like MG63 cells on silicon nitride ceramic discs.

The biocompatibility of silicon nitride (Si3N4) was assessed in an in vitro model using the human osteoblast-like MG-63 cell line. Cells were propagated on the surface of: reaction-bonded silicon nitride discs, sintered after reaction-bonded silicon nitride discs or control polystyrene surface for 48 h. Compared to cells propagated on polystyrene surface, cells grown on the surface of unpolished silicon nitride discs had significantly lower cell yield and decreased osteocalcin production. In contrast, cells on the surface of polished silicon nitride discs showed similar proliferative capacity to control cells propagated on polystyrene surface. Cells propagated on polished discs also produced higher levels of osteocalcin than cells on unpolished discs. SEM analysis showed cells with well-delineated morphology and cytoplasmic extensions when propagated on polished sintered after reaction-bonded discs. Cells appeared more spherical, when grown on polished reaction-bonded discs. The results of this study suggest that silicon nitride is a non-toxic, biocompatible ceramic surface for the propagation of functional human bone cells in vitro. Its high wear resistance and ability to support bone cell growth and metabolism make silicone nitride an attractive candidate for clinical application. Further studies are needed to explore the feasibility of using silicon nitride clinically as an orthopedic biomaterial.

Cell Culture Techniques↗
PubMed2002

A 1-year prospective clinical trial of balafilcon a (PureVision) silicone-hydrogel contact lenses used on a 30-day continuous wear schedule.

PURPOSE: To evaluate silicone-hydrogel balafilcon A (PureVision, Bausch & Lomb Inc., Rochester, NY) contact lenses worn on a 30-day continuous wear basis when compared with a traditional hydrogel (Acuvue, Vistakon, Johnson and Johnson Vision Products, Inc., Jacksonville, FL) worn on a 7-day extended wear schedule. DESIGN: Prospective, comparative, paired-eye, interventional, multicenter clinical trial. PARTICIPANTS: Two hundred twelve ametropes with no significant ocular pathology. METHODS: Subjects with normal ocular health who conformed to a set of standard criteria were monitored at seven different sites around the globe. Subjects wore both study lenses simultaneously, one on each eye. Lenses were assigned to right and left eyes according to a randomized schedule. The silicone hydrogel was removed and replaced every month and the traditional hydrogel was removed every 7 days and replaced at 14-day intervals. Subjects were followed for up to 1 year with discontinuation on indication divided between lens-related causes, unrelated factors, and loss to follow-up. MAIN OUTCOME MEASURES: Discontinuations, symptoms, vision, lens fit, lens surface assessment, slit-lamp assessment, and patient preferences. RESULTS: One hundred twenty three subjects completed the 12-month wearing period. There were no vision-threatening events with either lens type. The silicone-hydrogel lenses showed statistically superior performance in physiologic terms with regard to epithelial microcysts, striae, corneal staining, limbal injection, and bulbar injection. Inflammatory reactions, such as corneal infiltrates and tarsal conjunctival abnormalities occurred at similar rates between the lens types. Visible deposition and postlens debris with associated transient corneal indentation were significantly lower with the traditional hydrogel material at specific time points in the study. Visual acuity was comparable with the two lens types. Subjects rated the silicone-hydrogel material as preferable on subjective scales of dryness, comfort, and lens handling. Overall subjective performance was rated superior with the silicone-hydrogel material. CONCLUSIONS: The high oxygen performance of the silicone-hydrogel lenses provides a superior physiologic environment compared with a traditional hydrogel material during continuous wear. Despite the slightly higher levels of visible deposit on the silicone-hydrogels, superior subjective responses suggest that the plasma coating technology on these lenses is effective in providing comfortable lens wear. The results look promising for the success of silicone-hydrogels as the material of choice for continuous wear contact lenses.

Adolescent↗
PubMed1988

Extraction of retinol and cholesterol by intraocular silicone oils.

According to their solubility parameters, retinol and its derivatives, as well as cholesterol and other lipophilic substances, are predicted to dissolve in intraocular silicone and fluorosilicone oils. Calf retinas were extracted in vitro with these oils and the oils then analyzed spectrophotometrically. The following levels were found after extraction for 4 and 48 hours, respectively: for retinol, silicone oil, 0.5 and 3.7 micrograms/ml, and fluorosilicone oil, 0.5 and 3.3 micrograms/ml; for cholesterol, silicone oil, 0.5 and 6.4 micrograms/ml, and fluorosilicone oil, 0.8 and 3.7 micrograms/ml. In in vivo experiments, intraocular oils were removed from rabbit eyes at 4 days to 10 weeks after injection. The retinol levels were 1.7 to 11.4 micrograms/ml in silicone oil and 2.4 to 7.3 micrograms/ml in fluorosilicone oil; the cholesterol levels were 2.7 to 12.6 micrograms/ml in silicone oil and 7.5 to 15.6 micrograms/ml in fluorosilicone oil. Fluorosilicone and silicone oils (1000 cs) removed from human eyes at 7.3 and 102.0 weeks postoperatively had a retinol content of 5.4 and 2.9 micrograms/ml, respectively. Silicone oil of 1000 cs removed from a patient 51 weeks postoperatively and silicone oil of 12,500 cs removed 96 weeks postoperatively gave reaction characteristics for cholesterol, 230 and 99 micrograms/ml, respectively.

Animals↗
PubMed1992

Incidence and management of glaucoma after intravitreal silicone oil injection for complicated retinal detachments.

BACKGROUND: Intravitreal silicone oil injection used for managing complicated retinal detachments can be associated with elevated intraocular pressure (IOP). This study was undertaken to determine the incidence of glaucoma in patients who underwent silicone oil injection, as well as to evaluate the effectiveness of medical and surgical therapy in patients in whom glaucoma developed. METHODS: The postoperative courses of 50 eyes of 47 consecutive patients who underwent pars plana vitrectomy and silicone oil injection for the management of complicated retinal detachments were reviewed retrospectively. The outcomes of patients who underwent silicone oil removal and/or glaucoma surgery also were evaluated. RESULTS: The mean overall postoperative IOP before any glaucoma surgery was 16.7 +/- 9.3 mmHg (range, 0 to 45 mmHg), with a mean follow-up of 16.6 +/- 12.1 months (range, 2 to 51 months). Twenty-four (48%) eyes had postoperative IOPs of at least 25 mmHg and IOP elevations of at least 10 mmHg above the preoperative levels. Twenty-one (42%) eyes underwent complete removal of silicone oil and/or glaucoma surgery to effect IOP control. The IOPs were controlled to 21 mmHg or less (but > 5 mmHg) in 8 of 14 eyes that underwent removal of silicone oil alone, in 3 of 5 eyes that underwent Molteno implantation, and in 1 eye that underwent Nd:YAG transscleral cyclophotocoagulation, but not in 1 eye that underwent a modified Schocket procedure (mean follow-up, 13.5 +/- 11.0 months; range, 0.2 to 33 months). CONCLUSION: Intraocular pressure elevation is a common occurrence after intravitreal silicone oil injection. The underlying mechanism may often be multifactorial in nature. Patients in whom uncontrolled IOP develops may benefit from aggressive medical and/or surgical treatment with silicone oil removal, glaucoma implants, or cyclodestructive procedures.

Adolescent↗
PubMed1995

Condensation on the posterior surface of silicone intraocular lenses during fluid-air exchange.

PURPOSE: Posterior chamber foldable silicone intraocular lenses (IOLs) are becoming increasingly prevalent in patients undergoing a pars plana vitrectomy with fluid-air exchange. The authors report an important limitation of foldable silicone IOLs during fluid-air exchanges in pars plana vitrectomies. METHODS: The charts of 18 pseudophakic patients with foldable silicone IOLs who underwent vitrectomy with fluid-air exchange by the authors were reviewed. RESULTS: There was a statistically significant difference in the occurrence of condensation during fluid-air exchange between the group of patients with a capsulotomy versus those that did not have a capsulotomy (P = 0.003). Condensation limiting the view of the retina occurred during fluid-air exchange in 11 of 11 of the patients with foldable silicone lenses and a capsulotomy. Attempts to remove the condensation with a soft-tipped aspiration cannula resulted in limited view of the retina for 1 to 2 minutes in 6 of 11 patients. Use of a thin film of silicone oil restored the view in one patient. In the presence of an intact posterior capsule, condensation did not occur on identical foldable silicone IOLs in seven of seven patients. CONCLUSION: Recognition of the presence of a foldable silicone lens is important when an air-fluid exchange is anticipated. If a capsulotomy is present, the surgeon must be aware that condensation may limit the view of the retina severely during and after surgery. Intraoperatively, the view of the retina usually can be restored in short surgeries by wiping the posterior lens surface with a soft-tipped cannula, and in more complex surgeries by applying a thin film of silicone oil on the posterior surface of the lens.

Cataract Extraction↗
PubMed1998

Phacoemulsification and silicone oil removal through a single corneal incision.

OBJECTIVE: Cataracts are a frequent complication after silicone oil infusion for the repair of complicated retinal detachments, occurring in up to 100% of eyes retaining silicone oil for 6 months or more. The authors devised a combined procedure for cataract and silicone oil removal with intraocular lens (IOL) implantation through a single corneal incision and evaluated their results. DESIGN: A prospective, noncomparative case series. PARTICIPANTS: Thirty-four eyes of 34 consecutive patients with a history of retinal detachment repair requiring silicone oil placement in whom a clinically significant cataract subsequently developed were identified when removal of silicone oil was scheduled. INTERVENTION: All 34 eyes were prospectively entered into a study to evaluate the efficacy and potential complications of a combined procedure for cataract and silicone oil removal with posterior chamber lens implantation. All patients underwent uncomplicated phacoemulsification removal of cataract followed by removal of silicone oil and placement of an IOL through a single corneal incision. MAIN OUTCOME MEASURE: Recurrent retinal detachment and IOL-related complications were measured. RESULTS: Ten eyes had recurrent retinal detachments develop. Final visual acuity ranged from 6/12 to hand movements with 25 eyes (74%) showing stabilized or improved vision. Pre-existing macular pathology and recurrent retinal detachment generally were responsible for poor visual outcome. CONCLUSIONS: Combined phacoemulsification, IOL implant with silicone oil removal is a useful procedure in these complicated eyes. Visual outcome generally is good with improvement in visual acuity, even with recurrent retinal detachment or pre-existing macular pathology or both.

Adult↗
PubMed1998

Aspects of the bioinorganic chemistry of silicon in conjunction with the biometals calcium, iron and aluminium.

Silicon, in its various forms (silicic acid (Si(OH)4) through to hydrated amorphous silica (SiOn(OH)4-2n, n = 2-4) is important in geological and biological processes. Silicon is considered to be an 'essential' element for some plants and higher animals and when present as silica imparts structural, defensive and photosynthetic advantages to many plants. For the majority of essential elements specific molecular binding sites have been identified, but this is not the case for silicon. This has lead to the proposal that silicon may not act directly on biological systems but may exert its influence via interactions with biometals. Metals for which this may be a viable option include aluminium, iron and calcium, all of which can be found co-located with silicon in both minerals and living organisms. This article briefly reviews the pertinent solution and solid state chemistry of silicon in relation to aluminium, iron and calcium. Examples where silicon and an additional metal are found in solid state phases are described. The biological systems where these deposits are found are extremely complex and preliminary results from a model system designed to study silicon-biometal interactions are described.

Aluminum↗
PubMed2001

Phacoemulsification combined with silicone oil removal through a posterior capsulorhexis.

PURPOSE: To evaluate the technique of silicone oil removal through a posterior capsulorhexis combined with phacoemulsification and intraocular lens (IOL) implantation. SETTING: Dr. Rajendra Prasad Center for Ophthalmic Sciences, New Delhi, India. METHODS: Fifteen eyes of 15 patients had phacoemulsification with removal of silicone oil, which had been used for intraocular tamponade after a previous pars plana vitrectomy. Eyes with a stable retina were included in the series. In all eyes, the silicone oil was removed through a planned posterior capsulorhexis after phacoemulsification. The parameters evaluated were the primary diagnosis, duration between silicone oil instillation and phacoemulsification, type of cataract, preoperative and postoperative best corrected visual acuities (BCVAs), and complications such as frequency of retinal redetachment and secondary cataract. RESULTS: Vitreoretinal surgery with silicone oil instillation was performed for rhegmatogenous-tractional detachment resulting from Eales' disease in 6 eyes and from proliferative diabetic retinopathy in 2 eyes, for primary rhegmatogenous retinal detachment in 6 eyes, and for traumatic rhegmatogenous detachment in 1 eye. The mean duration between the silicone oil instillation and phacoemulsification was 7.5 months +/- 3.8 (SD). Fourteen eyes had posterior subcapsular cataract, and 10 had nuclear sclerosis. Preoperative BCVA was worse than 6/60 in all eyes. The BCVA was 6/60 or better in 9 eyes after a minimum follow-up of 6 months. Two eyes had choroidal detachment in the early postoperative period. No eye had vitreous hemorrhage, retinal redetachment, secondary cataract, clinically significant endothelial decompensation or macular edema, or a dislocated IOL. CONCLUSION: The results indicate that silicone oil removal through a posterior capsulorhexis during phacoemulsification is a viable option and can be performed in selected cases of cataract with previous silicone oil instillation and a stable retina.

Adolescent↗