Heavy tamponade 1: a review of indications, use, and complications

The Role of Eye Movements in the Process of Silicone Oil Emulsification After Vitreoretinal Surgery

Emulsification is a feared and common complication of the use of silicone oil (SO) as tamponade fluid after vitrectomy as it potentially associated with significant risks to ocular health, including elevated intraocular pressure (IOP), glaucoma, corneal and retinal changes. The aim of this study was to investigate the role and interplay of physical factors on the formation of SO emulsion. Experiments were performed in a model of the vitreous chamber with a realistic shape, filled with SO and an aqueous solution containing different concentrations of albumin, an endogenous protein known to modify the interfacial properties between SO and aqueous solutions. The model was subjected to harmonic and saccadic rotations and kept at body temperature. Results indicated that no emulsions were detected in the absence of albumin in the aqueous solution, while the presence of the protein facilitated emulsion formation, acting as a surfactant. Mechanical energy from eye movements was also found to be a key mechanism to produce emulsification, with higher mechanical energy provided to the system leading to smaller droplet sizes. The emulsions formed were stable over extended times. This study highlights the complex interplay of factors influencing SO emulsification in the vitreous chamber. A better understanding of the mechanisms underlying SO emulsification is crucial for developing strategies to mitigate SO emulsion and the related complications.

Vitreous substitutes and tamponades - A review of types, applications, and future directions

Vitreous substitutes and tamponades occupy the vitreous cavity following vitrectomy in the management of various conditions such as retinal detachment, macular hole, and diabetic retinopathy. Such replacements can be for the short term (gases such as sulfur hexafluoride (SF6) and perfluoropropane (C3F8) or long term (such as silicone oils). Certain substitutes such as perfluorocarbon liquids are used only transiently during surgery as "a third hand" or rarely till a few days post surgery. Hydrogels and hyaluronan derivatives are among the newer vitreous substitutes that are showing promise for the future, albeit still under investigation. still being investigated for use as vitreous substitutes. These materials have properties similar to the natural vitreous and may offer advantages such as improved biocompatibility and biodegradability. Although vitreous substitutes are valuable tools in treating vitreoretinal conditions, they carry risks and potential complications such as cataract formation, glaucoma, and inflammation. The current communication extensively reviews the available literature on vitreous tamponades. It details the composition and properties of various vitreous substitutes and tamponades available for the clinician, highlighting the techniques of usage, indications, and limitations.

Improved Outcomes with Heavy Silicone Oil in Complex Primary Retinal Detachment: A Large Multicenter Matched Cohort Study

PURPOSE

To establish whether Densiron 68, a heavier-than-water endotamponade agent, is an effective alternative to conventional light silicone oil in primary rhegmatogenous retinal detachment (RD) surgery for eyes with inferior breaks in the detached retina and severe proliferative vitreoretinopathy (PVR).

DESIGN

Cohort study of routinely collected data from the European Society of Retina Specialists and British and Eire Association of Vitreoretinal Surgeons vitreoretinal database between 2015 and 2022.

PARTICIPANTS

All consecutive eyes that underwent primary rhegmatogenous RD surgery using Densiron 68 or light silicone oil as an internal tamponade agent.

METHODS

To minimize confounding bias, we undertook 2:1 nearest-neighbor matching on inferior breaks, large inferior rhegmatogenous RDs, PVR, and, for visual analyses, baseline visual acuity (VA) between treatment groups. We fit regression models including prognostically relevant covariates, treatment-covariate interactions, and matching weights. We used g-computation with cluster-robust methods to estimate marginal effects. For nonlinear models, we calculated confidence intervals (CIs) using bias-corrected cluster bootstrapping with 9999 replications.

MAIN OUTCOME MEASURES

Presence of a fully attached retina and VA at least 2 months after oil removal.

RESULTS

Of 1061 eyes enrolled, 426 and 239 were included in our matched samples for anatomic and visual outcome analyses, respectively. The primary success rate was higher in the Densiron 68 group (113 of 142; 80%) compared with the light silicone oil group (180 of 284; 63%), with an adjusted odds ratio of 1.90 (95% CI, 1.63-2.23, P < 0.001). We also observed a significant improvement favoring Densiron 68 of -0.26 logarithm of the minimum angle of resolution (logMAR) in postoperative VA between the 2 groups (95% CI, -0.43 to -0.10, P = 0.002). The anatomic benefit of using Densiron 68 in eyes with inferior retinal breaks and large detachments was more pronounced among eyes with PVR grade C. We found no evidence of visual effect moderation by anatomic outcome or foveal attachment.

CONCLUSIONS

Densiron achieved higher anatomic success rates and improved visual outcomes compared with conventional light silicone oil in eyes with inferior retinal pathology and severe PVR.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

A minimum specification dataset for liquid ocular endotamponades: recommendations by a European expert panel

PURPOSE

To propose a minimum specification dataset to characterize liquid ocular endotamponades (OEs), namely silicone oil (SO), heavy SO (HSO), perfluorodecalin (PFD), and perfluoro-octane (PFO), in terms of physicochemical properties, purity and available evidence of safety, in line with ISO16672:2020.

METHODS

An evidence-based consensus using the expert panel technique was conducted. Two facilitators led a committee of 11 European experts. Facilitators prepared a dataset for each compound including the list of specifications relevant for the safety, identified by the group members on the basis of expertise and a comprehensive literature review. Each item was ranked by each member using a 9-point scale from 1 "absolutely to not include" to 9 "absolutely to include" in two rounds followed by discussion. Only items reaching consensus (score ≥ 7 from ≥ 75% of members) were included in the final datasets.

RESULTS

For all OEs, consensus was reached to include manufacturer, density, refractive index, chemical composition, dynamic viscosity, interfacial and surface tension, endotoxins, in vitro cytotoxicity assessment, and any evidence from ex vivo and/or in vivo tests for safety assessment. Additional specifications were added for SO (molecular weight distribution, content of oligosiloxanes with MW ≤ 1000 g/mol, spectral transmittance) and PFD/PFO (% of pure PFD/PFO in the final product, vapor pressure, chemical analyses performed for safety assessment).

CONCLUSION

The proposed evidence-based minimum specification datasets for SO, HSO, PFD, and PFO have the potential to provide surgeons and health service purchasers with an easily available overview of the most relevant information for the safety assessment of OEs.

Injectable alginate-based in situ self-healable transparent hydrogel as a vitreous substitute with a tamponading function

Retinal detachment and other vision-threatening disorders often necessitate vitreous body removal and tamponade injection for retina stabilization. Current clinical tamponades such as silicone oil and expansile gases have drawbacks, including patient discomfort and the need for secondary surgery. We introduce a transparent alginate-phenylboronic acid/polyvinyl alcohol composite hydrogel (TALPPH) as a novel vitreous substitute with tamponading capabilities. In vitro physicochemical, rheological, and optical characterization of in situ self-healable TALPPH was performed, and long-term biocompatibility was assessed in a rabbit model of vitrectomy retinal detachment. In vivo evaluations confirmed TALPPH's ability to inhibit retinal detachment recurrence and preserve rabbit vision without adverse effects. TALPPH's close resemblance to the natural vitreous body suggests potential as a vitreous tamponade substitute for future ophthalmological applications.

Risk Factors and Management of Intraocular Pressure Elevation After Vitrectomy Combined with Silicone Oil Tamponade

Silicone oil has emerged as the common option for intraocular tamponade during complicated retina vitrectomy. However, the postoperative elevation of intraocular pressure (IOP), influenced by numerous factors, remains a significant and frequently encountered complication that poses a potential threat to vision. Extensive research has been conducted to investigate the risk factors associated with elevated IOP following silicone oil tamponade, including silicone oil viscosity, preoperative high IOP, diabetes, and lens status. This comprehensive review aims to gather and summarize the current research findings regarding the risk factors contributing to IOP elevation following silicone oil tamponade, as well as the optimal management strategies for secondary glaucoma. The analysis includes the physicochemical properties of silicone oil, preoperative and intraoperative risk factors, and the effective management of secondary glaucoma. Enhancing our understanding of the primary factors associated with silicone oil-induced IOP elevation will facilitate the guidance of timely and appropriate interventions.

Use of Heavy Silicon Oil as Intraocular Tamponade for Inferior Retinal Detachment Complicated by Proliferative Vitreoretinopathy: A Multicentric Experience

INTRODUCTION

This is a multicentric study on the use of heavy silicon oil (HSO) as an intraocular tamponade for inferior retinal detachment (RD) complicated by proliferative vitreoretinopathy (PVR).

METHODS

139 eyes treated for RD with PVR were included in the study. 10 (7.2%) were affected by primary RD with inferior PVR, while 129 (92.8%) were affected by recurrent RD with inferior PVR. 102 eyes (73.9%) had received a silicon oil (SO) tamponade in a previous intervention prior to receiving HSO. Mean follow-up was 36.5 (standard deviation = 32.3) months.

RESULTS

The median interval between HSO injection and removal was 4 months (interquartile range: 3). At the time of HSO removal, the retina was attached in 120 eyes (87.6%), whereas in 17 eyes (12.4%), it had re-detached while the HSO was in situ. 32 eyes (23.2%) showed recurrent RD. A subsequent RD relapse was observed in 14.2% of cases with no RD at the time of HSO removal, and in 88.2% if an RD was present at the time of HSO removal. Advancing age showed a positive association with retinal attachment at the end of follow-up, while the risk of RD relapse at the end of the follow-up showed a significant negative association with HSO tamponade duration and with the use of SO rather than air or gas as post-HSO tamponade materials. Mean best corrected visual acuity was 1.1 logarithm of minimum angle of resolution at all follow-up time points. 56 cases (40.3%) needed treatment for elevated intraocular pressure (IOP), with which no clinically relevant variables were associated during follow-up.

CONCLUSION

HSO represents a safe and effective tamponade in cases of inferior RD with PVR. The presence of RD at the time of HSO removal is a negative prognostic factor for the development of a subsequent RD relapse. According to our findings, in cases of RD at the time of HSO removal, a short-term tamponade should definitely be avoided, in favor of SO. Special attention must be paid to the risk of IOP elevation, and patients should be closely monitored.

Semifluorinated Alkanes as New Drug Carriers-An Overview of Potential Medical and Clinical Applications

Fluorinated compounds have been used in clinical and biomedical applications for years. The newer class of semifluorinated alkanes (SFAs) has very interesting physicochemical properties including high gas solubility (e.g., for oxygen) and low surface tensions, such as the well-known perfluorocarbons (PFC). Due to their high propensity to assemble to interfaces, they can be used to formulate a variety of multiphase colloidal systems, including direct and reverse fluorocarbon emulsions, microbubbles and nanoemulsions, gels, dispersions, suspensions and aerosols. In addition, SFAs can dissolve lipophilic drugs and thus be used as new drug carriers or in new formulations. In vitreoretinal surgery and as eye drops, SFAs have become part of daily clinical practice. This review provides brief background information on the fluorinated compounds used in medicine and discusses the physicochemical properties and biocompatibility of SFAs. The clinically established use in vitreoretinal surgery and new developments in drug delivery as eye drops are described. The potential clinical applications for oxygen transport by SFAs as pure fluids into the lungs or as intravenous applications of SFA emulsions are presented. Finally, aspects of drug delivery with SFAs as topical, oral, intravenous (systemic) and pulmonary applications as well as protein delivery are covered. This manuscript provides an overview of the (potential) medical applications of semifluorinated alkanes. The databases of PubMed and Medline were searched until January 2023.

Anatomical and functional outcomes of short-term DensironXTRA heavy silicone oil for rhegmatogenous retinal detachments: a comparative case series

To assess the safety and efficacy of short-term DensironXTRA tamponade for repair of complicated rhegmatogenous retinal detachments (RRD). This is a retrospective consecutive case series of patients undergoing pars plana vitrectomy (PPV) with intravitreal DensironXTRA and a comparator group with gas (sulfur hexafluoride (SF₆) or perfluoropropane (C₃F₈)) tamponades by a single surgeon between January 2017 and November 2020 at a tertiary care centre. A total of 121 eyes with DensironXTRA and 81 comparator eyes with a gas tamponade were included. The DensironXTRA group had a significantly higher number of cases with inferior breaks (82% vs. 48%; p < 0.0001) and a history of previous PPV for RRD (64% vs. 12%; p < 0.0001). DensironXTRA was removed after a median period of 70 (IQR: 48.5-105.5) days. There was similar anatomical success in both the comparator gas tamponade and DensironXTRA groups (98.8% vs. 97.5%, p = 0.6506). Although both groups experienced a significant improvement in visual acuity, this change was significantly higher in the comparator gas tamponade group versus DensironXTRA group (p = 0.0017). There was no significant change in IOP in the DensironXTRA group (mean difference - 0.7; 95% CI - 1.753 to 0.331, p = 0.1785). The rates of complications were low and not significantly different between the two groups. There was no evidence for central macular thinning with DensironXTRA compared to the contralateral eye without RRD as well as with DensironXTRA in situ versus after its removal. DensironXTRA is a promising short-term tamponade agent with good anatomical and functional outcomes and low rates of complications for the repair of complicated RRDs.

Heavy silicone oil tamponade: a multicentre experience

OBJECTIVE

To report multicentred use of the heavy silicone oil Densiron 68 for anatomical reattachment following rhegmatogenous retinal detachment (RRD) repair and its associated complications.

METHODS AND ANALYSIS

Patients from seven vitreoretinal units within the UK that underwent RRD repair with Densiron 68 between January 2015 and December 2019 were identified. Primary outcome measures were primary and final reattachment rate, retained Densiron and failure rate. Secondary outcome measures were duration of tamponade, final visual acuity (VA) and complications of heavy silicone oil.

RESULTS

134 eyes of 134 patients were involved in the study. Primary surgical success was achieved in 48.5%, while a final reattachment rate of 73.4% was observed. The mean duration of Densiron 68 tamponade was 139.5 days. Mean final VA was 1.01 (range 0-2.9). 8 eyes (6.0%) required long-term topical steroids for anterior uveitis, whereas none of the eyes required long-term pressure-lowering treatment. Emulsification rate was 10.7% (6 eyes).

CONCLUSION

This is the largest real-world study on Densiron 68 in the UK. Densiron 68 facilitates tamponade of inferior retinal pathology and may be considered as an option for tamponade of inferior retinal pathologies.

Outcomes of Heavy Silicone Oil (Densiron) compared to Silicone Oil in primary rhegmatogenous retinal detachment: a multivariable regression model

PURPOSE

To measure the visual outcomes, proliferative vitreoretinopathy (PVR) and retinectomy rates following primary rhegmatogenous retinal detachment (RRD) repair, comparing silicone oil (SO) and heavy SO (Densiron).

METHODS

Retrospective, continuous comparative study from January 2017 to May 2021 of all primary RRD. Multivariable linear (logMAR gain) and binary-logistic (PVR-C and retinectomy rate) regression models to compare tamponade were performed. Covariates included age, gender, ocular co-morbidities, high myopia, macula-status, giant-retinal-tear (GRT), pre-op vision, PVR-C, oil type, perfluorocarbon-use, combined scleral buckle/vitrectomy, combined phaco-vitrectomy, 360-degrees-endolaser and oil duration. Cases with trauma or less than six-month follow-up were excluded.

RESULTS

A total of 259 primary RD were analysed. There were 179 SO patients and 80 Densiron patients that had six-month primary re-detachment in 18 (10.1%) and 8 (10.0%) respectively (p = 1.000). No difference in logMAR gain was detected between tamponade choice on multivariable linear regression. Subsequent glaucoma surgery was 5 (2.8%) and 4 (5.0%) for SO and Densiron patients respectively (p = 0.464). On multivariate binary-logistic regression we found no difference in development of PVR-C between oil tamponades. However, SO had significantly higher subsequent retinectomy rate compared to Densiron (odds ratio 15.3, 95% CI 1.9-125.5, p = 0.011). Duration of oil tamponade was not linked to differences in logMAR gain, PVR-C formation or increased retinectomy rate.

CONCLUSIONS

We report no difference in primary anatomical success, number of further RRD surgeries, subsequent glaucoma surgery, visual outcomes, PVR-C between both tamponades on multivariable models. Densiron oil was found to be more retinectomy sparing relative to SO.

Vitreous Substitutes as Drug Release Systems

Vitreous substitutes are traditionally used to stabilize the retina after vitrectomy. In recent years, various approaches have been developed for using the vitreous substitute not only as a tamponade but also as a drug release system to tackle ocular diseases. This review provides an overview of the requirements for vitreous substitutes and discusses the current clinically applied as well as novel polymer-based vitreous substitutes as drug delivery systems, including their release mechanisms, efficiencies, challenges, and future perspectives.

Managing PVR in the Era of Small Gauge Surgery

Proliferative vitreoretinopathy (PVR) is the leading cause of failed rhegmatogenous retinal detachment (RRD) surgery. Based upon the presence of clinical features and due to associated underlying risk factors, it is classified into various grades based upon its severity and extent of involvement. Despite excellent skills, flawless techniques, and high-end technology applied in the management of RRD, PVR still occurs in 5–10% of cases. Due to the advancements in wide angle viewing systems, advance vitrectomy machines and fluidics, early identification, use of long-term heavy silicon oil tamponades, high-speed cutters, small-gauge vitrectomies, use of perfluorocarbon liquid (PFCL), and small-gauge forceps and scissors, the success rate in the management of PVR has increased leading to improved anatomical outcomes. However, functional outcomes do not correlate well with improved anatomical outcomes. Various complications occur after RRD repair that are responsible for re-retinal detachment and recurrence of PVR. This article highlights causes, risk factors, classification, grading, diagnosis, and approach to management of PVR and post-PVR surgery complications.

Biocompatibility of intraocular liquid tamponade agents: an update

Intraocular liquids tamponade agents, such as perfluorocarbon liquids (PFCLs), semifluorinated alkanes (SFAs), silicone oils (SOs) and heavy silicone oils (HSOs), are a crucial intraoperative and/or postoperative tool in vitreoretinal surgery, in particular for the management of complex vitreoretinal diseases. However, their use is not without complications, which are potentially severe. Consequently, a growing interest has been devoted to the biocompatibility of these compounds and the adequacy of current regulations that should guarantee their safety. Obviously, an updated knowledge on research findings and potential risks associated to the use of intraocular liquid compounds is essential, not only for vitreoretinal surgeons, but also for any ophthalmologist involved in the management of patients receiving intraocular liquid tamponades. In light of this, the review provides a comprehensive characterisation of intraocular liquid tamponades, in terms of physical and chemical properties, current clinical use and possible complications. Moreover, this review focuses on the safety profile of these compounds, summarising the existing regulation and the available evidence on their biocompatibility.

Silicone oil in vitreoretinal surgery: indications, complications, new developments and alternative long-term tamponade agents

Silicone oil (SO) has been used as a long-term tamponade agent in the treatment of complicated vitreoretinal diseases for about half a century, during which time many advances in surgical techniques and technologies have been made. This review summarizes the chemical and physical properties of SO, its indications and complications, including particularly emulsification. The mechanisms and risk factors for emulsification are discussed, as well as novel strategies for its effective removal. Finally, the review focuses on new improved formulations of SO, including research into slow-release pharmacological agents within SO and provides an overview of alternatives to SO for the purpose of long-term tamponade that are being developed.

Results of different strategies to manage complicated retinal re-detachment

PURPOSE

Complicated retinal re-detachment with inferior proliferative vitreoretinopathy (PVR) remains a challenge. This study's aim was to compare vitrectomy with conventional silicon oil (CSO) combined with an encircling band (EB) and vitrectomy with heavy silicon oil (HSO) alone to treat retinal re-detachment through inferior PVR, where standard procedures have already failed.

METHODS

A retrospective analysis was done on patients with inferior complex re-detachment with secondary PVR after primary surgery, who received pars plana vitrectomy (PPV) with CSO combined with EB (group 1) or PPV alone with HSO (group 2) between December 2006 and August 2017. The primary endpoint was retinal reattachment, and the secondary endpoint was visual acuity (VA) change and complications in both groups.

RESULTS

This study included 119 eyes. Total single surgery anatomical success (SSAS) was 64%, with 80% (52/65) achieved in group 1 and 44.5% (24/54) in group 2 (p < 0.0001). The total final anatomical success (FAS) rate was 79% (94/119). In group 1, FAS was 91% (59/65) compared with 65% (35/54) in group 2 (p = 0.003). The pretreatment VA of group 1 had a median of 1.4 logMAR (95% CI 0.3-1.8), and group 2 showed a median of 1.4 logMAR (95% CI 0.2-1.8). The post-treatment decrease in group 1 was a median equal to - 0.6 versus - 0.1 for group 2 (p = 0.0001). Serious complications were similar in both groups.

CONCLUSION

For complicated retinal re-detachment through inferior PVR, the combination of PPV with EB may lead to better anatomical (SSAS, FAS) and functional success compared with PPV alone with HSO.

Impact of Vitreal Tamponade on Functional Outcomes in Vitrectomy with ILM Peeling in Primary Macula-Involving Retinal Detachment: A Retrospective Analysis

BACKGROUND

To compare visual outcomes of vitrectomy with internal limiting membrane (ILM) peeling and failed SF6 gas tamponade requiring silicone oil (SO) in a second procedure with primary SO tamponade in fovea-involving retinal detachment (FiRD).

METHODS

Retrospective analysis of 82 eyes with retinal detachment and mild, but without advanced proliferative retinopathy (PVR ≥C2) requiring vitrectomy for FiRD. Group 1 comprised 23 eyes that underwent SF6 tamponade resulting in re-detachment requiring revision surgery with secondary SO tamponade. Based on the intraoperative findings, group 2 patients had primarily received SO as vitreal tamponade (n=59). Patients receiving a scleral buckle surgery or with advanced PVR as well as patients with underlying vascular diseases and uveitis were excluded.

RESULTS

Preoperative visual acuity (Early Treatment Diabetic Retinopathy Study letters) was 13.5 ± 19.1 in group 1 and 14.0 ± 18.3 in group 2 (p=0.44). Twelve months after first surgery for FiRD, visual acuity was 49.8 ± 19.8 in group 1 and 51.7 ± 18.7 letters in group 2 (p=0.63). Re-detachment after SO removal requiring revision surgery developed in 17.4 (n=4) and 15.3% (n=9) cases.

CONCLUSION

Our findings suggest that if retinal traction is completely relieved at the end of surgery, vitrectomy with ILM peeling and SF6 may, if successful, improve the functional outcomes in instances with visual potential, ie, a foveal detachment of short duration despite the presence of a mild to moderate PVR, but with the inherent increased risk of re-detachment requiring further intervention and the use of a SO tamponade. Hence, secondary SO installation during re-vitrectomy after failed primary reattachment surgery results in similar functional outcomes as primary oil filling.

Outcome of pediatric retinal detachment using high-density silicone oil

BACKGROUND

The high-density silicone oil (Densiron), a mixture of F6H8 with silicone oil, has been used in the management of retinal detachment (RD) complicated by the presence of proliferative vitreoretinopathy (PVR) with varying rate of anatomical success and visual outcomes.

METHODS

We conducted a prospective interventional case series of 22 eyes in 22 children less than 18 years diagnosed with complicated retinal detachment complicated by the presence of PVR in inferior quadrant.

RESULTS

The mean age of the patients was 8.45 ± 3.36 years. There were 14 male and 8 female children. Five patients presented with total RD, 5 had subtotal RD and remaining 10 with inferior retinal detachment. There were 8 children with PVR C1, 13 with PVR C2, 3 with PVR C3. All patient's had macula off RD at presentation. The anatomical success in the form of attached retina was achieved in 21 (95.45%) eyes. Standard three-port pars plana vitrectomy without scleral buckling under general anesthesia was surgical technique employed in all cases.

CONCLUSION

Densiron can be an important tamponade agent in pediatric retinal detachment complicated by PVR with increased success rate of retinal re-attachment.

Double Retinal Tamponade for Treatment of Rhegmatogenous Retinal Detachment with Proliferative Vitreoretinopathy and Inferior Breaks

Purpose

To evaluate the efficacy and safety of the simultaneous use of short-term perfluoro-n-octane (PFO) with perfluoropropane (C3F8) gas to achieve retinal reattachment in eyes with rhegmatogenous retinal detachment (RRD) with proliferative vitreoretinopathy (PVR) grade C and multiple retinal breaks including inferior breaks.

Design

This is a prospective interventional case series study. Patients and Methods. The study was a prospective noncomparative interventional study. It included 30 eyes of 30 patients who had RRD with PVR grade C and multiple retinal breaks including inferior tears attending the vitreoretinal unit of Minia University Hospital, Egypt. The mean age was 50.2 ± 10.63 years; 18 patients were females and 12 were males. Combined phacoemulsification and 23 G pars plana vitrectomy (PPV) with double retinal tamponade by C3F8 and PFO were done, and PFO was removed in 10–14 days. The patients were followed up for one year. The primary outcome was to achieve successful retinal reattachment, and the secondary outcomes were visual improvement and occurrence of complications.

Results

Successful retinal reattachment was obtained in 28 eyes out of 30 (93.3%), and 2 eyes (6.7%) had recurrent RD. Best-corrected distance visual acuity (BCDVA) in logMAR was significantly improved from baseline 1.74 ± 0.05 to 0.93 ± 0.04, 0.82 ± 0.05, 0.80 ± 0.07, and 0.73 ± 0.055 at follow-up visits 3, 6, and 9 months and one year, respectively (P ≤ 0.001). There were no serious ocular complications recorded.

Conclusions

The results of this study indicated that primary vitrectomy with simultaneous use of both C3F8 and short-term PFO as retinal tamponades was effective and safe in the management of complex cases of RRD with PVR grade C and inferior breaks. This trial is registered with NCT04168255.

Supine positioning after vitrectomy for rhegmatogenous retinal detachments with inferior retinal breaks

Background

To evaluate the effectiveness of face up position (FUP) following pars plana vitrectomy (PPV) and silicone oil injection in cases of rhegmatogenous retinal detachment (RRD) with multiple peripheral and inferior breaks.

Method

Thirty-two eyes of 32 patients with RRD due to multiple peripheral breaks were managed with PPV and silicone oil as endotamponade. Postoperatively, all patients were instructed to assume face up (supine) position for at least 10 days. Silicone oil was removed 3 to 6 months postoperatively in eyes with attached retina and the patients were followed up for 6 months.

Results

Thirty eyes (94%) got a successful attachment of the retina and remained attached after silicone oil removal. One case showed lower redetachment under silicone oil while the other case showed recurrent RRD after silicone oil removal.

Conclusion

Although postoperative FUP is not a popular one, it is effective in the treatment of RRD with peripheral breaks whatever the number or the distribution of these breaks. This may in some way or another change the traditional trends of postoperative positioning after vitrectomy for RRD.

Transient Macular Thinning during the Use of Heavy Silicone Oil, Densiron 68

BACKGROUND

To evaluate the effect of short-term Densiron tamponade on macular thickness.

METHODS

Retrospective case series. Data were collected from charts of patients who received short-term (less than 90 days) Densiron tamponade. The OCT parameters were compared between Densiron in situ and after Densiron removal and to the fellow eye.

RESULTS

Twenty eyes were included in the analysis. Although there was a trend toward thinner CRT with Densiron in situ in situ the operated eye when compared to the fellow eye (248 and 264 microns, respectively, p = .066), this difference disappeared after DR. At the final OCT there was a statistically significant recovery in the CRT (from 248 to 277 microns, P = .001) and no statistical difference between operated and the fellow eye (p = .265) with no evidence of ERM or CME.

CONCLUSIONS

We found transient macular thinning that resolved after Densiron removal with no evidence of long-term macular thinning in eyes treated with Densiron tamponade for retinal detachment.

Densiron® 68 Heavy Silicone Oil As A Short-Term Intraocular Tamponade For Macula-On Inferior Retinal Detachments - A Case Series

PURPOSE

To describe our experience using short term Heavy Silicone oil (Densiron® 68®) for Macula-On inferior rhegmatogenous retinal detachments (RRD) with inferior retinal breaks.

METHODS

Retrospective, consecutive, observational case series. Data was retrospectively collected from the medical records of patients who underwent pars plana vitrectomy and Densiron® 68 endotamponade for macula-on RRD repair.

RESULTS

Eight patients were included in the study. The mean patient age was 57.1 ± 12.3 (±SD) years. The mean time to Densiron® 68 removal was 57.8 ± 17.8 (±SD) days (ranging from 24 to 83 days). One patient (12.5%) detached three weeks after Densiron® 68 removal and required further surgery. All patients were attached at last follow up with a mean follow up of 192 days. The mean final BCVA was 20/40 (0.29 logMAR), similar to the 20/45 pre-operative BCVA (0.35 logMAR, p=0.501). No significant emulsification was noted before or during the removal of the Densiron® 68. Two patients developed an increase in intraocular pressure (IOP) before Densiron® 68 removal that resolved after removal. One patient developed cystoid macular edema (CME) that resolved with a short course of topical medications, and one patient had persistent CME that required an intravitreal triamcinolone acetate 1% injection.

CONCLUSION

The high anatomic success rate, good visual outcomes, and minimal complications suggest that Densiron® 68 be considered as a short-term tamponade for macula-on retinal detachments with inferior pathology.

Perfluorocarbon liquid-assisted inverted inner limiting membrane-flap for large macular hole after recurrent rhegmatogenous retinal detachment

A 45-year-old Caucasian myopic woman with a severe vision impairment (20/320) in the left eye due to a macula-off rhegmatogenous retinal detachment (RRD) underwent vitrectomy with silicone oil tamponade followed by an inferior relaxing retinectomy with heavy silicone oil tamponade during the second procedure for recurrence of RRD due to proliferative vitreoretinopathy. Four weeks after the second surgery, visual acuity was 20/200 and the patient complained metamorphopsia in the same eye due to a large full-thickness macular hole. A perfluorocarbon liquid-assisted inverted inner limiting membrane-flap technique was performed. Visual acuity improved to 20/80 after closing of macular hole and partial recovery of outer retinal layers at 3 months from the last surgery.

Tamponade in surgery for retinal detachment associated with proliferative vitreoretinopathy

BACKGROUND

Retinal detachment (RD) with proliferative vitreoretinopathy (PVR) often requires surgery to restore normal anatomy and to stabilize or improve vision. PVR usually occurs in association with recurrent RD (that is, after initial retinal re-attachment surgery), but occasionally may be associated with primary RD. Either way, for both circumstances a tamponade agent (gas or silicone oil) is needed during surgery to reduce the rate of postoperative recurrent RD.

OBJECTIVES

The objective of this review was to assess the relative safety and effectiveness of various tamponade agents used with surgery for RD complicated by PVR.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (the Cochrane Library 2019, Issue 1), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to January 2019), Embase (January 1980 to January 2019), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to January 2019), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 2 January 2019.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) on participants undergoing surgery for RD associated with PVR that compared various tamponade agents.

DATA COLLECTION AND ANALYSIS

Two review authors screened the search results independently. We used the standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified four RCTs (601 participants) that provided data for the primary and secondary outcomes. Three RCTs provided data on visual acuity, two reported on macular attachment, one on retinal reattachment and another two on adverse events such as RD, worsening visual acuity and intraocular pressure. Study Characteristics Participants' characteristics varied across studies and across intervention groups, with an age range between 21 to 89 years, and were predominantly men. The Silicone Study was conducted in the USA and consisted of two RCTs: (silicone oil versus sulfur hexafluoride (SF₆) gas tamponades; 151 participants) and (silicone oil versus perfluropropane (C₃F₈) gas tamponades; 271 participants). The third RCT compared heavy silicone oil (a mixture of perfluorohexyloctane (F₆H₈) and silicone oil) with standard silicone oil (either 1000 centistokes or 5000 centistokes; 94 participants). The fourth RCT compared 1000 centistokes with 5000 centistokes silicone oil in 85 participants. We assessed most RCTs at low or unclear risk of bias for most 'Risk of bias' domains. Findings Although SF₆ gas was reported to be associated with worse anatomic and visual outcomes than was silicone oil at one year (quantitative data not reported), at two years, silicone oil compared to SF₆ gas showed no evidence of a difference in visual acuity (33% versus 51%; risk ratio (RR) 1.57; 95% confidence interval (CI) 0.93 to 2.66; 1 RCT, 87 participants; low-certainty evidence). At one year, another RCT comparing silicone oil and C₃F₈ gas found no evidence of a difference in visual acuity between the two groups (41% versus 39%; RR 0.97; 95% CI 0.73 to 1.31; 1 RCT, 264 participants; low-certainty evidence). In a third RCT, participants treated with standard silicone oil compared to those receiving heavy silicone oil also showed no evidence of a difference in the change in visual acuity at one year, measured on logMAR scale ( mean difference -0.03 logMAR; 95% CI -0.35 to 0.29; 1 RCT; 93 participants; low-certainty evidence). The fourth RCT with 5000-centistoke and 1000-centistoke comparisons did not report data on visual acuity. For macular attachment, participants treated with silicone oil may probably experience more favorable outcomes than did participants who received SF₆ at both one year (quantitative data not reported) and two years (58% versus 79%; RR 1.37; 95% CI 1.01 to 1.86; 1 RCT; 87 participants; low-certainty evidence). In another RCT, silicone oil compared to C₃F₈ at one year found no evidence of difference in macular attachment (RR 1.00; 95% CI 0.86 to 1.15; 1 RCT, 264 participants; low-certainty evidence). One RCT that compared 5000 centistokes to 1000 centistoke reported that retinal reattachment was successful in 67 participants (78.8%) with first surgery and 79 participants (92.9%) with the second surgery, and no evidence of between-group difference (1 RCT; 85 participants; low-certainty evidence). The fourth RCT that compared standard silicone oil with heavy silicone oil did not report on macular attachment. Adverse events In one RCT (86 participants), those receiving standard 1000 centistoke silicone oil compared with those of the 5000 centistoke silicone oil showed no evidence of a difference in intraocular pressure elevation at 18 months (24% versus 22%; RR 0.90; 95% CI 0.41 to 1.94; low-certainty evidence), visually significant cataract (49% versus 64%; RR 1.30; 95% CI 0.89 to 1.89; low-certainty evidence), and incidence of retina detachment after the removal of silicone oil (RR 0.36 95% CI 0.08 to 1.67; low-certainty evidence). Another RCT that compared standard silicone oil with heavy silicone oil suggests no difference in retinal detachment at one year (25% versus 22%; RR 0.89; 95% CI 0.54 to 1.48; 1 RCT; 186 participants; low-certainty evidence). Retinal detachment was not reported in the RCTs that compared silicone oil versus SF₆ and silicone oil versus to C₃F₈.

AUTHORS' CONCLUSIONS

There do not appear to be any major differences in outcomes between C₃F₈ and silicone oil. Silicone oil may be better than SF₆ for macular attachment and other short-term outcomes. The choice of a tamponade agent should be individualized for each patient. The use of either C₃F₈ or standard silicone oil appears reasonable for most patients with RD associated with PVR. Heavy silicone oil, which is not available for routine clinical use in the USA, may not demonstrate evidence of superiority over standard silicone oil.

Life and death of liquid-infused surfaces: a review on the choice, analysis and fate of the infused liquid layer

We review the rational choice, the analysis, the depletion and the properties imparted by the liquid layer in liquid-infused surfaces – a new class of low-adhesion surface.

A human amniotic membrane plug to repair retinal detachment associated with large macular tear

PURPOSE

To describe a surgical technique, using a human amniotic membrane (hAM) plug, in two cases of retinal detachment with a large macular tear.

METHODS

Surgical technique description with surgical video. A 23-gauge pars plana vitrectomy with peripheral retinectomy was performed. An hAM plug was implanted under the neuroretina to seal the posterior retinal break. Standard silicone oil tamponade was performed at the end of the surgery. The patients were positioned face down after the operation for the first 2 weeks. Optical coherence tomography (OCT) scans were performed in the follow-ups.

RESULTS

The 1 week postoperative OCT showed a neuroretina ingrowth over the hAM plug. The 3-month OCT showed a regenerated neurosensory retina entirely covering the hAM plug. Visual acuity improved from light perception to 20/400 (LogMAR 1,3) 3 months after the operation in both patients. The silicone oil was extracted 4 months after surgery, and no recurrences were observed. The patients' visual acuity remained stable at 20/400 after the silicone oil extraction.

CONCLUSION

In these complex cases, hAM transplantation can be a valid option not only to help the retinal reattachment but also for a partial regenerative effect which, in these cases, was accompanied by a visual acuity recovery.

[Toxicity of heavy liquids]

BACKGROUND

Acute toxicity of perfluorocarbon liquids (PFCL) is a relevant problem in retinal surgery due to impurities in the medicinal product.

OBJECTIVE

This article gives an overview of the current problems, possible explanations, interactions with other medicinal products and approaches to improved patient safety.

RESULTS

Toxicity is caused by impurities in the raw material but can also be caused by interactions with other medicinal products or drugs. The current test procedures do not ideally represent the ophthalmological application but there are promising activities to set the course for the future.

CONCLUSION

The use of PFCL in retinal surgery is generally considered safe. Users should pay attention to the quality of medicinal products.

Perfluorodecalin Versus Densiron 68 Heavy Silicone Oil in the Management of Inferior Retinal Detachment Recurrence

BACKGROUND AND OBJECTIVE

To assess the efficacy of perfluorodecalin (PFD) or Densiron 68 heavy silicone oil (HSO) in the management of inferior complex retinal detachment recurrence.

PATIENTS AND METHODS

A retrospective, comparative consecutive case series study. Twenty-four eyes of 24 patients affected by inferior complex retinal detachment recurrence underwent pars plana vitrectomy with PFD or HSO as endotamponade. All patients recruited were affected by complicated inferior retinal detachments and had already undergone at least one vitreoretinal procedure. The primary endpoint was anatomical success with primary and secondary surgery. The secondary endpoints were functional outcome and inflammatory complications.

RESULTS

Out of 24 cases of inferior retinal detachment recurrence, 12 were tamponed with PFD (PFD group) and 12 with HSO (D68 group). Retinal reattachment rate at first surgery was 50% for the D68 group and 66.6% for the PFD group. Final reattachment rate after two or more surgical operations was 91.6% for the PFD group and 83.3% for the D68 group. Best-corrected visual acuity improved in both groups from a mean of 1.00 logMAR (20/200; standard deviation [SD]: 1) to 0.60 logMAR (20/80; SD: 0.3), and from a mean of 1.81 logMAR (20/2000; SD: 1.1) to a mean of 2.00 logMAR (20/2,000; SD:1) for the PFD and D68 groups, respectively.

CONCLUSION

Both the endotamponades used showed good results in solving inferior retinal detachment recurrence with a slightly better rate in the PFD group, but it was not statistically significant (P > .05). [Ophthalmic Surg Lasers Imaging Retina. 2019;50:274-280.].

Long-Term Outcome of Patients Operated with Pars Plana Vitrectomy for Primary Rhegmatogenous Retinal Detachment

PURPOSE

To determine the long-term outcome of patients operated with pars plana vitrectomy (PPV) for primary rhegmatogenous retinal detachment (RRD) and to identify potential predictors for poor visual outcome.

METHODS

Prospective, observational 30-month study of patients operated for primary RRD with PPV. Examinations were performed preoperatively and after months 2, 6, and 30.

RESULTS

Eighty-four patients (84 eyes) were included and 73 (86.9%) participated at month 30. The macula was attached in 30 (35.7%) patients at primary operation. The majority of patients (n = 59, 80.8%) achieved a good final best corrected visual acuity (BCVA ≤0.3 logMAR, ≥0.5 Snellen) with a better outcome in patients with the macula attached than detached (0.02 vs. 0.17 logMAR, p = 0.007). Variables associated with poor visual outcome were baseline BCVA >0.3 logMAR (p = 0.03), female gender (p = 0.02), silicone oil (p = 0.03), and larger areas of retinal detachment (p = 0.01). In multivariable regression analysis, female gender (OR = 8.5 [95% CI 1.8-39.8]) was the strongest risk factor for poor visual outcome.

CONCLUSION

The majority of patients operated for primary RRD achieved a reasonable long-term visual outcome. Notably, female gender was associated with poor visual outcome, indicating a need for closer follow-up.

Densiron 68 heavy silicone oil in the management of inferior retinal detachment recurrence: analysis on functional and anatomical outcomes and complications

AIM

To assess the efficacy and safety of a heavy silicone oil (Densiron 68) in the management of inferior retinal detachment recurrence.

METHODS

A retrospective non-comparative consecutive case series study. Forty-nine cases of complex inferior retinal detachment were treated using Densiron 68 heavy silicone oil (HSO) as the endotamponade. Our main purpose was anatomic reattachment following Densiron 68 removal. Functional outcomes, rate of recurrences, the presence of inflammatory complications and intraocular pressure alterations were evaluated.

RESULTS

Forty-nine patients affected by complex retinal re-detachment were recruited. The mean follow-up was 7.6 (±1.5) mo. The mean best corrected visual acuity after Densiron 68 removal was 0.95 logMAR, standard error (SE: 0.068). Retinal reattachment was 61.2% after first surgery and 81.6% after second surgery. Nineteen cases (38.8%) had recurrences when intraocular heavy silicon oil was in situ, 26.3% (5 cases) of which involved the inferior retina.

CONCLUSION

Densiron 68 efficiently fills the inferior retinal periphery and might lower the risk of inferior proliferative vitreoretinopathy development, in particular after a standard silicon oil tamponade that reduces the proliferative process in the upper quadrants of the retina.

A Review of Surgical Outcomes and Advances for Macular Holes

The surgical outcomes of macular holes (MHs) have improved greatly in recent years. The closure rate is as high as 90-100%, but the outcomes of some special types of MHs remain unsatisfactory. Internal limiting membrane (ILM) peeling dramatically improves the anatomic success rate, but recent studies have found that it could also cause mechanical and subclinical traumatic changes to the retina. Dyes are widely used, and apart from indocyanine green (ICG), the toxicities of other dyes require further research. Face-down posturing is necessary for MHs larger than 400 μm, and the duration of this posture is determined by the type of tamponade and the case. The ellipsoid zone has been shown to be highly correlated with visual outcome and recovery. New surgical methods include the inverted ILM flap technique and the ILM abrasion technique. However, they require further research to determine their effectiveness.

Goldmann Applanation Tonometry versus Dynamic Contour Tonometry after Vitrectomy with Silicone Oil Endotamponade

PURPOSE

To evaluate the agreement of intraocular pressure (IOP) measurements using dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) in eyes after vitrectomy with silicone oil endotamponade and controls.

METHODS

In this prospective comparative study, IOP was measured with GAT and DCT in 30 eyes with oil endotamponade 1-3 days after vitrectomy and 40 untreated controls. In addition, ocular pulse amplitude (OPA), corneal pachymetry (CCT), and axial length (AL) were measured.

RESULTS

GAT values in the oil group were significantly higher compared to control eyes (mean GAT oil 13.6 ± 5.1 mmHg; mean GAT control 10.8 ± 2.1 mmHg; p = 0.003). There was no significant difference in DCT measurements (mean DCT oil 12.0 ± 4.1 mmHg; mean DCT control 11.9 ± 2.9 mmHg; p = 0.9). This led to a significant difference of GAT-DCT between the oil and control group (mean difference of GAT-DCT oil 1.6 ± 4.7 mmHg; mean difference of GAT-DCT control -1.1 ± 2.6 mmHg; p = 0.004). The difference between GAT and DCT was negatively correlated with the mean IOP measured by both methods (r = -0.36, p = 0.02) and positively correlated with CCT only in the control group (r = 0.36, p = 0.02), as well as to AL only in the oil group (r = 0.46, p = 0.01). The OPA did not differ significantly between groups.

CONCLUSION

GAT and DCT showed a good agreement in control eyes. The difference of GAT and DCT is significantly changed in eyes after vitrectomy with silicone oil endotamponade. Our findings suggest that GAT overestimates IOP in this situation.

Intracranial Migration of Silicone Delaying Life Saving Surgical Management: A Mimicker of Hemorrhage

We present a case in which intraocular silicone injection for complex retinal detachment resulted in migration and distribution of silicone along the intracranial visual pathway, and ultimately throughout the ventricular system. Misinterpretation of this material as intracranial hemorrhage on outside computed tomography imaging delayed emergent repair of a Type A aortic dissection until the diagnosis was made on repeat imaging. A discussion of this case and salient computed tomography and magnetic resonance imaging characteristics of silicone is provided.

DOUBLE PSEUDOHYPOPYON FROM EMULSIFIED HEAVY SILICONE OIL

PURPOSE

To report a patient with double pseudohypopyon from emulsification of heavy silicone oil.

METHODS

A 65-year-old woman with rhegmatogenous retinal detachment and a large inferior break underwent pars plana vitrectomy and heavy silicone oil (Oxane HD; Bausch and Lomb, Toulouse, France) tamponade. Eighteen months later, she returned for follow-up examination.

RESULTS

Slit-lamp examination revealed accumulation of emulsified silicone oil in both the inferior and superior portions of the anterior chamber leading to a "double pseudohypopyon" appearance.

CONCLUSION

This case highlights the possibility of decomposition of the Oxane HD silicone oil with time creating an inverted pseudohypopyon from emulsification of light silicone oil in addition to a pseudohypopyon from heavy oil emulsification.

Recent Progress in Using Biomaterials as Vitreous Substitutes

Vitreous substitutes are crucial adjuncts during vitreo-retinal surgery for retinal diseases such as complicated retinal detachment, macular holes, complications of diabetic retinopathy, and ocular trauma involving posterior segment. In retinal detachment surgery, an internal tamponade agent is required to provide internal pressure for reattachment of the detached neurosensory retina. Current available options serve only as a temporary surgical adduct or short-term solution and are associated with inherent problems. Despite many years of intensive research, an ideal vitreous substitute remains elusive. Indeed, the development of an ideal vitreous substitute requires the concerted efforts of synthetic chemists and biomaterial engineers, as well as ophthalmic surgeons. In this review, we propose that polymeric hydrogels present the future of artificial vitreous substitutes due to its high water composition, optical transparency, and rheological properties that closely mimic the natural vitreous. In particular, thermosensitive smart hydrogels, with reversible sol to gel change, have emerged as the material class with the most potential to succeed as ideal vitreous substitutes, facilitating easy implementation during surgery. Importantly, these smart hydrogels also display potential as efficacious drug delivery systems.

Long-term heavy silicone oil intraocular tamponade

Heavy silicone oil tamponade is intended to be temporary, but may occasionally be indefinite in patients who refuse, or are deemed unsuitable for, further surgery. The aim of this study is to compare the outcomes of patients with temporary versus indefinite heavy silicone oil intraocular tamponade. This retrospective, comparative case series identified 75 patients who underwent heavy silicone oil instillation (Oxane HD) over a 6 year period (2006-2012) in one institution. Thirty-nine patients had temporary heavy oil tamponade and 36 patients had indefinite tamponade. The majority (68 %) of patients had a history of previous vitreoretinal surgery prior to oil instillation and 66.7 % had pre-existing proliferative vitreoretinopathy (PVR). The mean final logMAR best corrected visual acuity (BCVA) was significantly better in the temporary tamponade group (1.34 ± 0.66) than the indefinite tamponade group 1.82 ± 0.64 (p = 0.003). Ambulatory BCVA (≥ 4/200) was retained in 76.3 % of temporary tamponade patients versus 54.3 % of indefinite tamponade patients (p = 0.093). Successful retinal reattachment was significantly more likely in temporary tamponade patients (92.3 %) than indefinite tamponade patients (75 %; p = 0.04). Complications in the patients with indefinite heavy silicone oil tamponade included redetachment (38.9 %), corneal pathology (13.8 %), secondary glaucoma (11.1 %) and anterior segment emulsification (8.3 %).While temporary tamponade patients had better outcomes than those with indefinite tamponade, the majority of indefinite tamponade patients still retained ambulatory vision in the affected eye. Indefinite heavy silicone oil tamponade remains a viable option for those who cannot undergo removal of oil surgery.

Development of emulsification resistant heavier-than-water tamponades using high molecular weight silicone oil polymers

PURPOSE

Developing new blends of heavier-than-water silicone oil tamponade agents containing high molecular weight polydimethylsiloxane polymer for use in vitreoretinal surgery.

MATERIALS AND METHODS

The viscoelastic properties of heavier-than-water silicone oil blends (30.5% F6H8 + 69.5% polydimethylsiloxane) containing high molecular weight polymer additive at increasing concentrations were measured using a controlled-stress rheometer (TA Instruments Rheolyst AR 1000 N). Emulsification of the blends was induced using a sonication device and a pluronic surfactant as a strong emulsifier. The percentage emulsion area was photographed and measured using ImageJ software. In a second in vitro emulsification assessment, silicone oil blends were dispersed using a high shear homogenizer and the oil-in-water droplets were counted using a coulter counter particle analyser.

RESULTS

The addition of the high molecular weight polymer increased shear viscosity and viscoelasticity of the oil blends, which were measureable and to some extent predictable. The in vitro emulsification models produced contradictory results. This demonstrates the difficulty of designing and using in vitro models to evaluate the emulsification tendency of tamponade agents in vivo.

CONCLUSION

Addition of a high molecular weight polymer to heavy silicone oil can increase the viscoelasticity. These findings might contribute to the development of emulsification resistant heavy silicone oils.

Mechanical models of the dynamics of vitreous substitutes

We discuss some aspects of the fluid dynamics of vitreous substitutes in the vitreous chamber, focussing on the flow induced by rotations of the eye bulb. We use simple, yet not trivial, theoretical models to highlight mechanical concepts that are relevant to understand the dynamics of vitreous substitutes and also to identify ideal properties for vitreous replacement fluids. We first recall results by previous authors, showing that the maximum shear stress on the retina grows with increasing viscosity of the fluid up to a saturation value. We then investigate how the wall shear stress changes if a thin layer of aqueous humour is present in the vitreous chamber, separating the retina from the vitreous replacement fluid. The theoretical predictions show that the existence of a thin layer of aqueous is sufficient to substantially decrease the shear stress on the retina. We finally discuss a theoretical model that predicts the stability conditions of the interface between the aqueous and a vitreous substitute. We discuss the implications of this model to understand the mechanisms leading to the formation of emulsion in the vitreous chamber, showing that instability of the interface is possible in a range of parameters relevant for the human eye.

Heavy silicone oil and intraocular inflammation

In the past two decades, many advances have been made in vitrectomy instrumentation, surgical techniques, and the use of different tamponade agents. These agents serve close retinal breaks, confine eventual retinal redetachment, and prevent proliferative vitreoretinopathy (PVR). Long-acting gases and silicone oil are effective internal tamponade agents; however, because their specific gravity is lower than that of the vitreous fluid, they may provide adequate support for the superior retina but lack efficacy for the inferior retina, especially when the fill is subtotal. Thus, a specific role may exist for an internal tamponade agent with a higher specific gravity, such as heavy silicone oils (HSOs), Densiron 68, Oxane HD, HWS 45-300, HWS 46-3000, and HeavySil. Some clinical evidence seems to presume that heavy tamponades are more prone to intraocular inflammation than standard silicone if they remain in the eye for several months. In this review, we discuss the fundamental clinical and biochemical/molecular mechanisms involved in the inflammatory response after the use of heavy tamponade: toxicity due to impurities or instability of the agent, direct toxicity and immunogenicity, oil emulsification, and mechanical injury due to gravity. The physical and chemical properties of various HSOs and their efficacy and safety profiles are also described.

Tamponade or filling effect: changes of forces in myopic eyes

Myopia is the most common ocular abnormality. Its high and growing prevalence has contributed to a recent surge in surgical interest in the disorder, since retinal detachment in eyes with high myopia differs from that in emmetropic eyes or eyes with low myopia. The myopic eye, because of its specific anatomy, poses special challenges that need to be overcome to ensure the appropriate use of vitreous substitutes. However, intraocular tamponades have shown great potential for revolutionizing retinal detachment surgery and vitreomacular surgery in general in myopic eyes. We provide an updated review of the clinical use of vitreous substitutes in the myopic eye, paying particular attention to analyzing the ideal function of endotamponade agents and comparing the effects of these agents on the physical and biological properties of the eye.

Anatomical and functional outcomes after Densiron 68 heavy silicone oil tamponade for complicated retinal detachment in Chinese eyes

AIM

To evaluate the safety and efficacy of Densiron 68 heavy silicone oil (HSO) tamponade for complicated retinal detachment (RD) in Chinese eyes.

METHODS

Twenty-one eyes of 21 patients with complicated RD were included in this retrospective study. All patients underwent pars plana vitrectomy with an internal tamponade using Densiron 68 HSO. Anatomical and functional results and complications were evaluated, including retinal status, visual acuity (VA), intraocular pressure (IOP), intraocular inflammation, lens opacity, and HSO emulsification.

RESULTS

All the patients were followed up for 3mo to 1y (5.8±1.16mo). Retinal reattachment was achieved in 19 of 21 patients (90.5%). VA improved in 18 of 21 patients (85.7%), from 1.93 logMAR (±0.48) to 1.52 logMAR (±0.45) (P=0.001). Postoperative complications included early dispersion of HSO in 7 eyes (38.8%), cataract in 10 of 18 phakic eyes (55.5%), moderate postoperative inflammation reaction in 10 eyes (47.6%), and elevated IOP in 5 eyes (23.8%), all of which were controlled by medication or by surgery.

CONCLUSION

High anatomical and functional success rates can be achieved with primary vitrectomy for complicated RD by using Densiron 68 HSO; however, it should not be ignored that Densiron 68 HSO can cause some complications in the eye.