Visual loss following removal of intraocular silicone oil.
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AIM: To investigate the cause of visual loss following removal of intraocular silicone oil in patients who underwent vitrectomies for retinal detachment or giant retinal tear. METHODS: The clinical records of three cases with visual loss following removal of silicone oil were reviewed. Investigations carried out included fundus fluorescein angiogram, optical coherence tomography, and electrophysiological studies. RESULTS: Visual acuities dropped from 6/9 to 6/36 in two cases and 6/24 to 3/24 in the third. None of the three cases had macula detachment at any stage. Fundus fluorescein angiogram and optical coherence tomography were normal in all cases. Pattern electroretinogram showed reduced amplitudes of the P50 and N95 components. Multifocal electroretinogram indicated a selective damage to the central part of the macula. CONCLUSIONS: The results suggest that the abnormality arises predominantly in the central part of the macula, especially the outer and middle layers. However, the exact mechanism still remains obscure. (+info)
An experimental study on the effect of encircling band procedure on silicone oil emulsification.
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AIM: Silicone oil is a useful tamponading material used in complex vitroretinal surgery. However, the use of silicone oil is associated with emulsification which can lead to vision threatening complications. The authors developed an experimental model to study the effect of encircling band on silicone oil emulsification. METHODS: Two identical artificial eye chambers were constructed with circumferential indentations placed at the sphere's equator (mimicking an encircling band indentation), and filled with varying amounts of Silicone Oil 1000 centistrokes (Adato, Bausch and Lomb, UK) and balanced salt solution. The chambers were then placed on a horizontal rotating shaker, mimicking physiological saccadic eye movements, which spun the chambers at 100 Hz for 5 days at 37 degrees C. Emulsification was then quantified by dark field microscopy, digital photography, and manual counting by a masked observer. RESULTS: The mean (standard deviation (SD)) values of silicone emulsification bubbles were as follows: in the 90% silicone oil filled chamber with no encircling band, 139.1 (SD 313.4); in the 90% silicone oil filled chamber with encircling band, 10.9 (SD 22.2) (p<0.0001); in the 75% silicone oil filled chamber with no encircling band, 103.6 (SD 272.6); in the 75% silicone oil filled chamber with encircling band, 18.5 (SD 32), (p = 0.001). CONCLUSIONS: The emulsification of silicone oil results from friction between the silicone oil and aqueous liquids. The results from this study suggest silicone oil emulsification is reduced by (1) more complete silicone oil fill and (2) indentation from an encircling band. The authors hypothesise that both these measures resulted in reduced emulsification by reducing silicone oil/aqueous movement and resulting shearing forces. (+info)
Can the sequential use of conventional silicone oil and heavy oil be a strategy for the management of proliferative vitreoretinopathy?
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INTRODUCTION: Densiron is a novel long-term tamponade. Its specific gravity is 1.06 g/mL and as such it is heavier than water and provides support for the inferior retina. As proliferative vitreoretinopathy (PVR) has a propensity for the inferior retina, we used Densiron on a consecutive series of 97 cases with inferior pathology. We hypothesised that the sequential use of conventional and heavy silicone oil is a strategy for the management of PVR. MATERIALS AND METHODS: A consecutive interventional case series involving the use of Densiron for PVR cases was studied. Patients were selected if conventional silicone oil and Densiron were used sequentially. Anatomical success was defined as total re-attachment in the absence of any tamponade agent for at least 3 months post oil removal. RESULTS: Of the 97 patients, 10 patients fulfilled the criteria. Surgery involving Densiron was successful in re-attaching the retina in 7 of 10 cases, with one sequence of alternating light then heavy oil operation, and with one further surgery using silicone oil in the remaining 3 cases. The mean LogMAR preoperative vision was 1.57 and the postoperative vision was 0.82. In 8 of 10 patients, the final vision was 20/200 or better; in 5 of 10 patients, 20/80 or better. The mean follow-up was 19.5 months (range, 9 to 45). CONCLUSIONS: The sequential use of conventional silicone oil and Densiron may be a strategy in reducing the number of re-operations. Our case series shows that despite multiple surgical procedures, favourable visual outcome can be achieved. (+info)
Comparison of silicon oil removal with various viscosities after complex retinal detachment surgery.
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BACKGROUND: Despite the progress in vitreoretinal surgery and the importance of silicone oil as an adjunct for the treatment of complex forms of retinal detachment, controversy still surrounds the issue of selecting the proper oil viscosity for clinical use. Herein, we evaluate the outcomes of retinal detachment (RD) surgery after removing silicone oils of different viscosities. METHODS: In this retrospective cohort study, eighty-two eyes with surgically re-attached retinas, of which 53 were filled with 5000 cs silicone oil and 29 with 1000 cs silicone oil were enrolled. We evaluated the outcomes and complications following silicone oil removal. Final anatomic success (stable re-attachment), final visual acuity (VA) and intraocular pressure (IOP)were recorded and analysed. RESULTS: Of 82 eyes, 41 had proliferative vitreoretinopathy (PVR), 24 were associated with intraocular foreign bodies, 10 had endophthalmitis and 7 had proliferative diabetic retinopathy with tractional retinal detachment. Prior to silicone oil removal, the retina was attached in all eyes, 29% had VA > or = 6/120 and 52% had IOP > or = 21 mmHg. After silicone oil removal, the retina remained attached in 59(72%) of the eyes, 34% had VA > or = 6/120 and 9% had IOP > or = 21 mmHg. Comparing 1000 cs and 5000 cs silicone oil filled eyes, redetachment occurred more frequently in the latter group especially in cases with associated PVR. Final VA worse than 6/120 was associated with initial VA < 6/120 (OR = 32.2 95%CI 7.4-140.2) and use of 5000 cs silicone oil (OR = 7.9 95%CI 1.9-32.2). No factor was significantly associated with final IOP > or = 21 mmHg. CONCLUSION: In complicated retinal detachment surgery, use of 5000 cs silicone oil may be associated with a poorer anatomic and visual outcome compared with 1000 cs silicone oil. However there was no difference between the two viscosities in IOP elevation. A randomized controlled study is necessary to further evaluate such a possibility. (+info)
Effects of emulsification, purity, and fluorination of silicone oil on human retinal pigment epithelial cells.
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When silicone oil is used as a vitreous substitute, reproliferation of vitreoretinal membranes beneath the oil occurs frequently. Nevertheless, the effects of various properties of silicone oils such as purity, viscosity, fluorination, or emulsification on cellular proliferation have not been established. Human retinal pigment epithelial (RPE) cells were grown to confluence on filters, and then covered with silicone oil. The cellular monolayers were fed from below. At 72 hr and 14 days a proliferation index was determined by measuring 3H-thymidine incorporation into the cells. An assay for the enzyme gamma-glutamyl-transpeptidase (gamma GTP) was also done to assess cell polarization under some oils. A total of 14 different oils were studied. At 72 hr, emulsified oil was associated with significantly less proliferation than unemulsified oil, a difference that disappeared at 2 weeks. Neither fluorination nor viscosity had a significant effect on RPE proliferation. In addition, RPE proliferation indices were not significantly different from one another when purified oils were compared with most commercial-grade oils. However, a very contaminated oil was associated with a significantly higher proliferation index compared with severe purified or medical-grade oils. (+info)
Factors contributing to the emulsification of intraocular silicone and fluorosilicone oils.
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Silicone oil (SiO) and fluorosilicone oil (FSiO) are used as vitreous substitutes during retinal detachment surgery. Emulsification of these oils causes complications in oil-injected eyes. One factor contributing to emulsification is interfacial tension (gamma i) of the oils. In general, the lower the gamma i, the more easily the oils are emulsified. We measured the gamma i of SiO and FSiO by the ring method at 37 degrees C; corrected the measured values by the Harkins-Jordan table or the Zuidema-Waters equation; and found that the gamma i between the oils and liquefied bovine vitreous was low compared with the gamma i between the oils and water (eg, gamma i of 1000 centistokes [cs]SiO against liquefied vitreous and water was 16.0 and 42.8 dyne/cm, and that of 1000 cs FSiO was 14.7 and 38.7 dyne/cm, respectively). When SiO or FSiO and liquefied vitreous were shaken in a partially filled vial, both oils were emulsified regardless of viscosity and purity. However, when the vial was filled completely (a situation in which the hydrodynamic condition of the oils may be similar to that in the eye), SiO of 1000 and 12,500 cs and FSiO of 10,000 cs did not emulsify, although FSiO of 1000 cs did emulsify. SiO was less emulsified than FSiO of the same viscosity, possibly because the smaller density difference between SiO and intraocular fluids makes agitation difficult compared with FSiO. High viscosity of the oils restricted mechanical emulsification, which was not prevented by eliminating low-molecular-weight components of the oils. Residual catalysts may relate to spontaneous emulsification, which was observed occasionally with high-viscosity SiO in water. (+info)
Immunopathology of intraocular silicone oil: enucleated eyes.
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AIMS: To characterise the distribution of silicone oil in ocular tissues in globes enucleated after complicated retinal detachment, and to document the distribution and nature of any associated inflammatory response. METHOD: 9 enucleated globes that had previously undergone retinal detachment surgery with silicone oil and 7 control globes that had undergone enucleation after retinal detachment surgery (n = 2) or ocular trauma (n = 5) were studied. Sections were histologically examined using light microscopy to document the distribution of silicone oil in ocular tissues. Immunohistochemical analysis was carried out using the ABC technique and a panel of monoclonal and polyclonal antibodies. Electron microscopy was undertaken to observe the penetration of silicone oil in the trabecular meshwork of the anterior chamber drainage angle. RESULTS: Silicone oil was distributed throughout the globes-notably in the iris, ciliary body, retina, trabecular meshwork and epiretinal membranes. Focal areas of intraretinal silicone were associated with disorganised retinal architecture, retinectomy sites or subretinal oil. The distribution of macrophages was closely related to the distribution of silicone oil. T and B lymphocytes were not associated with silicone oil unless additional pathology was also present-for example, cyclitic membrane or uveitis. One of the nine eyes had silicone oil present in the optic nerve. In the control globes, the inflammatory response was mediated primarily by macrophages and T lymphocytes, and was less marked than that observed in the silicone oil globes. CONCLUSION: This study shows that silicone oil may be sequestered in varied ocular tissues and is associated with localised inflammation mediated by macrophages. (+info)
Immunopathology of intraocular silicone oil: retina and epiretinal membranes.
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AIMS: To determine the inflammatory response in retina and epiretinal membranes after intraocular silicone oil tamponade. METHODS: 14 proliferative vitreoretinopathy (PVR) epiretinal membranes, 33 retro-oil epiretinal membranes, 19 retinectomies, 14 retro-oil retinectomies and 37 idiopathic epiretinal membranes (controls) underwent immunohistochemical analysis using the avidin-biotin complex technique and a panel of monoclonal and polyclonal antibodies. The number of positive cells counted in five 0.5 mm diameter fields of immunohistochemical sections was graded on a score of 1-4. RESULTS: Macrophage cell counts were significantly greater in membranes with a history of exposure to silicone oil (p<0.001). An inflammatory response could be observed within 1 month of silicone oil exchange, and the intensity seemed to be unrelated to the duration of exposure. Macrophages were confined to epiretinal membranes on the surface of retinectomy specimens in 10 of 14 cases and intraretinal macrophages were observed only in specimens with gliotic retina. T and B lymphocytes were rarely seen in the specimens examined. Marked glial cell up regulation was observed in 11 of 16 retinectomy specimens and in 8 of 11 retro-oil retinectomies. Glial cell content was variable in the membranes, but there was a trend of increased presence after exposure to silicone oil. CONCLUSION: This study has shown that the use of silicone oil is accompanied by an inflammatory reaction, primarily mediated by bloodborne macrophages. This response can be observed within 1 month of silicone oil injection and continues after silicone oil removal. Retinal surgeons should be aware of the potential secondary effects of intraocular silicone oil when they are considering its use (and removal) in vitreoretinal surgery. (+info)