Perfluorocarbons and semifluorinated alkanes

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 from Bench to the Operating Room in a Translational Approach: Review and Future Endeavors in Vitreoretinal Surgery

Vitreous substitutes are indispensable tools in vitreoretinal surgery. The two crucial functions of these substitutes are their ability to displace intravitreal fluid from the retinal surface and to allow the retina to adhere to the retinal pigment epithelium. Today, vitreoretinal surgeons can choose among a plethora of vitreous tamponades, and the tamponade of choice might be difficult to determine in the ever-expanding range of possibilities for a favorable outcome. The currently available vitreous substitutes have disadvantages that need to be addressed to improve the surgical outcome achievable today. Herein, the fundamental physical and chemical proprieties of all vitreous substitutes are reported, and their use and clinical applications are described alongside some surgical techniques of intra-operative manipulation. The major upcoming developments in vitreous substitutes are extensively discussed, keeping a translational perspective throughout. Conclusions on future perspectives are derived through an in-depth analysis of what is lacking today in terms of desired outcomes and biomaterials technology.

Ex vivo evaluation of retinal cytotoxicity after the use of multiple medical devices in pars plana vitrectomy in porcine eyes

This study aimed to evaluate viability of retinal cells after the use of multiple intraoperative devices, namely a vitreal dye (triamcinolone acetonide,TA), a ERM/ILM dye (solution of trypan blue 0.15% and brilliant blue 0.025%), and two intraocular tamponades, namely perfluoro-n-octane, (PFO) and silicone oil (SO 1000 cSt), with minimal and maximal removal of their residues, during a simulated pars plana vitrectomy (PPV) in porcine eyes ex-vivo. The in vitro cytotoxicity of each of these compounds was verified on ARPE-19 cells by direct tests according to the ISO 10993-5 (2009). Pars plana vitrectomy was performed on 25 enucleated porcine eyes divided in five groups according to the following conditions: Group A) No surgery control: eye bulbs were kept at room temperature for 40 min; Group B) Sham surgery: PPV with the sole use of BSS for 40 min; Group C) Cytotoxic control: PPV with BSS infusion (20 min) followed by intravitreal injection of 1H-PFO (contact time: 20 min); Group D) Surgery with residues: PPV with BSS infusion and sequential intravitreal injection of TA, ERM/ILM dye, PFO and SO, with minimal removal of each compound after a specified contact-time (overall duration: 40 min); Group E) Surgery with minimal residues: PPV performed as in group D, but with maximal removal of each compound (overall duration: 40 min). All the experimental procedures were performed at room temperature. Immediately after surgery, the retina was extracted from each eye bulb and samples of 3-mm diameter were prepared. Retinal viability was determined for each sample by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide assay. A cell viability <70% was considered the cytotoxicity threshold. Kruskal-Wallis test was used to evaluate the differences in retinal viability between groups. No cytotoxicity was detected in retinal samples in groups A, B and E. Samples from eye bulbs that had undergone surgery with minimal removal of residues (group D) and cytotoxic controls (group C) showed high retinal cytotoxicity. The tested conditions indicated that the combined use of TA, ERM/ILM dye, PFO and SO during PPV does not affect retinal cells viability if all the devices are properly removed, whereas the cytotoxicity detected in group D may suggest that the presence and accumulation of the residues of the compounds used intraoperatively could negatively impact retinal viability due to a cumulative and/or synergistic cytotoxic effect between them, supporting the crucial role of an optimal removal of the intraoperative medical devices to ensure a safe vitrectomy to the patient.

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.

Inhalationally Administered Semifluorinated Alkanes (SFAs) as Drug Carriers in an Experimental Model of Acute Respiratory Distress Syndrome

Aerosol therapy in patients suffering from acute respiratory distress syndrome (ARDS) has so far failed in improving patients' outcomes. This might be because dependent lung areas cannot be reached by conventional aerosols. Due to their physicochemical properties, semifluorinated alkanes (SFAs) could address this problem. After induction of ARDS, 26 pigs were randomized into three groups: (1) control (Sham), (2) perfluorohexyloctane (F6H8), and (3) F6H8-ibuprofen. Using a nebulization catheter, (2) received 1 mL/kg F6H8 while (3) received 1 mL/kg F6H8 with 6 mg/mL ibuprofen. Ibuprofen plasma and lung tissue concentration, bronchoalveolar lavage (BAL) fluid concentration of TNF-α, IL-8, and IL-6, and lung mechanics were measured. The ibuprofen concentration was equally distributed to the dependent parts of the right lungs. Pharmacokinetic data demonstrated systemic absorption of ibuprofen proofing a transport across the alveolo-capillary membrane. A significantly lower TNF-α concentration was observed in (2) and (3) when compared to the control group (1). There were no significant differences in IL-8 and IL-6 concentrations and lung mechanics. F6H8 aerosol seemed to be a suitable carrier for pulmonary drug delivery to dependent ARDS lung regions without having negative effects on lung mechanics.

Substitutes and Colloidal System for Vitreous Replacement and Drug Delivery: Recent Progress and Future Prospective

Vitreoretinal surgeries for ocular diseases such as complicated retinal detachment, diabetic retinopathy, macular holes and ocular trauma has led to the development of various tamponades over the years in search for an ideal vitreous substitute. Current clinically used tamponade agents such as air, perfluorocarbons, silicone oil and expansile gases serve only as a short-term solution and harbors various disadvantages. However, an ideal long-term substitute is yet to be discovered and recent research emphasizes on the potential of polymeric hydrogels as an ideal vitreous substitute. This review highlights the recent progress in the field of vitreous substitution. Suitability and adverse effects of various tamponade agents in present day clinical use and biomaterials in the experimental phase have been outlined and discussed. In addition, we introduced the anatomy and functions of the native vitreous body and the pathological conditions which require vitreous replacement.

Small-scale preparation of perfluorocarbon-nanoemulsions utilizing dual centrifugation

BACKGROUND

Perfluorocarbon-nanoemulsions (PFC-NE) made of PFC and phospholipids (PL) by homogenization are optimal for in vivo-¹⁹F labelling of monocytes and subsequently of inflamed tissues in magnetic resonance imaging (MRI). Necessary requirements for in vivo use of PFC-NE are sterility, suitable droplet sizes and the absence of immune activating liposomes, which are a typical byproduct of the homogenization process.

METHODS AND RESULTS

To meet these requirements, we developed an aseptic in-vial preparation technique for PFC-NE based on dual centrifugation (DC) by testing different PFC/phospholipid ratios as well as the application of additives. Two different PFC, perfluorooctylbromide (PFOB) and perfluoro-15-crown-5-ether (PFCE), were investigated. Particle sizes were assessed by dynamic light scattering and NE morphology by cryoTEM. DC homogenization was optimal when using an excess of PL (8.7 % (m/m) of utilized PFC, z-ave: 180 nm, pdi: 0.2). A purification approach by centrifugation was implemented to remove liposomes formed from the excess of PL during homogenization. The purification success was proven by phospholipid assay and PFC quantification via density and sound velocity measurements.

CONCLUSION

DC in combination with a short centrifugation is a fast and reliable way of small-scale aseptic PFC-NE production for ¹⁹F MRI passive-targeting experiments of monocytes and inflamed tissues.

Advances in the treatment of rhegmatogenous retinal detachment

The pathogenesis of rhegmatogenous retinal detachment depends on three factors, namely, retinal rupture, vitreous liquefaction and traction causing the retina to separate from the pigment epithelium, among which retinal rupture is the most important. Retinopathy is caused by a gap between the neurosensory retina and the retinal pigment epithelium, which severely damages the visual function of the patient. Therefore, early clinical discovery, prevention and selection of an appropriate treatment are important. This article reviews progress in the treatment of retinal detachment.

THE CURRENT SURGICAL MANAGEMENT OF LARGE, RECURRENT, OR PERSISTENT MACULAR HOLES

PURPOSE

To evaluate the current surgical options available for the management of large (>400 μm), recurrent, or persistent macular holes (MHs).

METHODS

A review of the literature was performed, focusing on the epidemiology, pathophysiology, diagnosis, and surgical treatments of large, recurrent, or persistent MHs. Based on this review, a comprehensive overview was provided regarding the topic of large, recurrent, or persistent MHs and focused on recent surgical management updates.

RESULTS

For large MHs, variations of the inverted internal limiting membrane flap technique demonstrated promising rates of primary hole closure and significant visual acuity improvements. For recurrent or recalcitrant MHs, early repeat vitrectomy with extension of the internal limiting membrane peel remains the most straightforward and optimal surgical technique to achieve secondary closure. Regardless of the surgical approach, the goal of each technique described is to induce or aid in stimulating gliosis within the MH to maximize closure.

CONCLUSION

Despite the high success rate of modern MH surgery, large, recurrent, or persistent MHs remain a challenge for retinal surgeons. This review provides a detailed summary on the rationality and efficacy of current surgical options.

A New, Heavier-Than-Water Silicone Oil: A Solution of Perfluorohexyloctane in Polydimethylsiloxane

Purpose

To prepare and explore new solutions of semifluorinated alkane in silicone oil, which have a specific gravity slightly higher than silicone oil and vitreous fluid (referred to in the following as heavier-than-water silicone oils (HWSs), and to investigate, in vitro, whether HWSs can be used to plug retina holes, while allowing dehydration of the subretinal space.

Methods

HWS solutions were prepared with silicone oil 5000 and perfluorohexyloctane (F6H8). The stability was investigated under different conditions. The viscosity was determined by means of a capillary viscometer. The surface and interface tension were measured using the ring method.

Results

HWSS are insoluble in an aqueous medium. Densiron®68 (HWS 1.06) is a transparent homogeneous liquid which is slightly heavier (1.06 g/cm3) than water and has a refractive index close to that of vitreous liquid. Densiron®68 (HWS 1.06) has a low viscosity (1480 mPas) and interface tension (40.82 mN/m), making it an effective tamponade in the surgical treatment of an inferior detached retina. In addition, the interfaces between Densiron®68 and other perfluorocarbon liquids are clearly visible. However, the interface layer between Densiron®68 and water is not clear. Finally, all HWSs are stable over the long term at ambient temperatures, as well as physically and thermally resistant.

Conclusions

Due to its physiochemical properties, Densiron®68 could meet the requirements for a heavier-than-water tamponade.

TREATMENT OF PERSISTENTLY OPEN MACULAR HOLES WITH HEAVY SILICONE OIL (DENSIRON 68) VERSUS C2F6. A PROSPECTIVE RANDOMIZED STUDY

PURPOSE

To compare the efficacy of a mixture of silicone oil and perfluorohexyloctane (Densiron 68) with C2F6 gas endotamponade in the retreatment of persistently open full-thickness macular holes.

METHODS

In this prospective randomized study, 21 consecutive patients who were unsuccessfully operated on for large idiopathic full-thickness macular hole were randomly assigned to undergo a second vitrectomy with 20% perfluoroethane gas (C2F6, Group A) or with Densiron 68 tamponade (Group B).

PRIMARY OUTCOMES

Endpoint (12 months) full-thickness macular hole closure rate by spectral domain optical coherence tomography and logMAR corrected distance visual acuity.

SECONDARY OUTCOMES

postoperative adverse events.

RESULTS

The mean diameter of macular holes before the second pars plana vitrectomy was 680.3 ± 120.8 μm and 740.5 ± 105.3 μm in Groups A and B, respectively (P = 0.237); mean preoperative corrected distance visual acuity was 0.96 ± 0.36 logMAR and 1.12 ± 0.35 logMAR, respectively (P = 0.315). Endpoint full-thickness macular hole closure was obtained in 30% of patients (3/10) in Group A and in 82% (9/11) in Group B (P = 0.030). Corrected distance visual acuities were, respectively, 0.80 ± 0.25 logMAR and 0.55 ± 0.20 logMAR, with significant intergroup difference (P = 0.019); corrected distance visual acuity increased in Group B only (P = 0.003). No differences in complications were found.

CONCLUSION

The results indicate that Densiron 68 tamponade could be a useful, safe, and more efficacious method than gas tamponade to retreat persisting macular holes.

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.

Vitreous substitutes: the present and the future

Vitreoretinal surgery has advanced in numerous directions during recent years. The removal of the vitreous body is one of the main characteristics of this surgical procedure. Several molecules have been tested in the past to fill the vitreous cavity and to mimic its functions. We here review the currently available vitreous substitutes, focusing on their molecular properties and functions, together with their adverse effects. Afterwards we describe the characteristics of the ideal vitreous substitute. The challenges facing every ophthalmology researcher are to reach a long-term intraocular permanence of vitreous substitute with total inertness of the molecule injected and the control of inflammatory reactions. We report new polymers with gelification characteristics and smart hydrogels representing the future of vitreoretinal surgery. Finally, we describe the current studies on vitreous regeneration and cell cultures to create new intraocular gels with optimal biocompatibility and rheological properties.

Towards an ideal biomaterial for vitreous replacement: Historical overview and future trends

Removal of the natural vitreous body from the eye and its substitution with a tamponade agent may be necessary in cases of complicated retinal detachment. Many materials have been variously proposed and tested over the years in an attempt to find an ideal vitreous substitute. This review highlights the evolution of research in the field of vitreous replacement and chronicles the main advances that have been made in such a context. The suitability and limitations of vitreous tamponade agents and substitutes in current clinical use are examined, and the future promise of experimentally tested biomaterials are described and discussed. Future trends in research are also considered and, specifically, the great potential of polymeric hydrogels is emphasized, as they seem to be very effective in closely mimicking the features of the natural vitreous and they could successfully act as long-term vitreous substitutes without inducing clinical complications in the patient's eye.

Histopathology and Ultrastructure of Rabbit Retina After Intravitreous Injection of Perfluorohexyloctane (F6H8)

PURPOSE

To describe changes in rabbit retina after intravitreous injection of perfluorohexyloctane (F6H8).

METHODS

Intravitreous injections of C3F8 were performed in the right eye of 48 male New Zealand albino rabbits. All 48 eyes were injected with C3F8. The animals were divided in three groups of 18 each. 18 eyes (6 in each group) were used as controls and 30 (10 in each group) were further injected with F6H8. Animals were sacrificed at days 15, 30, and 60 and the eyes processed for light and electron microscopy and immunohistochemistry.

RESULTS

Vitreous tracts were observed behind the lens in all groups. Epiretinal and retrolental membranes developed in most of the treated eyes. Light microscopy showed retinal vacuolization in all eyes. No significant ultrastructural changes appeared in any of them. Macrophages were observed in the inner limiting membrane.

CONCLUSIONS

Ultrastructural findings can be considered signs of good tolerance to F6H8, though the appearance of epiretinal membranes associated with the presence of macrophagic response suggests we should refrain from using F6H8 until results from clinical trials are available.

A new heavy internal tamponade in vitreoretinal surgery: an in vitro study

AimTo study the solubility of perfluorohexyloctane (F6H8) in silicone oil (polydimethylsiloxane (PDMS) 1000) and to measure the viscosity and the specific gravity of the mixture obtained (heavy silicone oil or HSO tamponade) to define the ideal ratio of these components.MethodsThe solubility diagram of the mixture was obtained with the turbidimetric method, indicating the miscibility of F6H8 and silicone oil 1000 at all the useful temperatures. The viscosity was measured in steady shear conditions by using a controlled stress rheometer (Haake RS150) and a double cone/plate (DC 60/4) system, both at 25 and 37 degrees C for different volume per cent compositions of the mixture. The specific gravity was measured at 37 degrees C using a digital densimeter.ResultsA mixture of F6H8 30 v% and PDMS 70 v% was found to be transparent and stable at all the useful temperatures. By combining these proportions of the two substances, a resultant density of 1.06 g/cm(3) was obtained. The viscosity of the 30% F6H8 mixture was 203 mPa.s at 25 degrees C and 163 mPa.s at 37 degrees C respectively.ConclusionsThe ideal F6H8 and silicone oil mixture can be obtained combining 30% of F6H8 with 70% of silicone oil 1000. This mixture seems to have rheological properties useful for its use as an alternative intraocular heavy tamponade.Eye (2008) 22, 1082-1088; doi:10.1038/eye.2008.144; published online 6 June 2008.

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

BACKGROUND

Heavier than water intraocular tamponades have several theoretical advantages over conventional tamponades, especially in the treatment of complicated retinal detachments and proliferative viteroretinopathy of the lower fundus periphery. However, initial clinical series of various heavy tamponades have reported significant complication rates. Therefore, heavy tamponades have not found widespread acceptance. Three recently developed heavy silicone oil tamponades, Oxane HD, Densiron 68, and HWS 46-3000, are much better tolerated and presently seem to enter routine clinical practice.

MATERIALS AND METHODS

Literature review of 21 publications on the clinical application of 9 different heavy tamponades (fluorosilicone, C10F18, F6H8, OL62HV, Oxane HD, O62, F6H8-silicone oil mixture, Densiron 68, and HWS 46-3000).

RESULTS

The first generation (fluorinated silicone and perfluorocarbon liquids) and second generation (partially fluorinated alkanes) of heavy tamponades were associated with relatively high complication rates, for example, tamponade emulsification, intraocular inflammation, and rise in intraocular pressure. The complication spectrum of the new generation of heavy silicone oils (Oxane HD, Densiron 68, and HWS 46-3000) seems to be comparable to conventional silicone oil tamponades while providing better support for the inferior retina and the posterior pole.

CONCLUSION

The recently developed heavy silicone oil tamponades are safe and effective tools for the use of complicated retinal detachments of the inferior fundus.

Recent trends in the management of rhegmatogenous retinal detachment

It has been nearly a century since Jules Gonin performed the first intervention for rhegmatogenous retinal detachment, trans-scleral cautery, achieving successful outcomes in close to 50% of his cases. With the introduction of alternative surgical approaches in the last half-century, including Charles Schepens' scleral buckle technique and Robert Machemer's pars plana vitrectomy, the surgical success rates have risen to close to 90%. Nonetheless, despite dramatic progress in the success of reattachment surgeries, reasonable disagreement exists as to which approach (or combination of approaches) is the best form of surgical intervention for patients with rhegmatogenous retinal detachments. In this review, the authors summarize the current knowledge of retinal detachment, and examine emerging results from the first large scale, prospective, randomized, controlled clinical trials addressing the efficacy of these surgical approaches for retinal detachment, with the hope of identifying the most appropriate (evidence-based) therapeutic intervention for the treatment of rhegmatogenous retinal detachment.

Biocompatibility assessment of liquid artificial vitreous replacements: relevance of in vitro studies

The biocompatibility of liquid artificial vitreous replacements is generally assessed by performing tests in animal models before their clinical use, whereas in vitro experimentation is seldom carried out due to their physico-chemical characteristics. Since their introduction in vitreoretinal surgery, however, the use of some certified vitreous replacements has been discouraged after clinical trials, because of the occurrence of serious side effects. This observation suggests that the tests currently performed for biocompatibility assessment cannot fully guarantee their safety when they are used in humans. Here we review the available literature on in vitro biocompatibility testing of liquid artificial vitreous replacements and survey our own experience on the subject, obtained by using primary retinal cell cultures, seeded on micro-porous inserts. We suggest that in vitro biocompatibility assessment, conducted before experiments in animal models, could improve the required safety evaluation and decrease the risk of undesired side effects, as well as providing a beneficial reduction of animal experimentation.

A NEW HEAVY SILICONE OIL (HWS 46-3000) USED AS A PROLONGED INTERNAL TAMPONADE AGENT IN COMPLICATED VITREORETINAL SURGERY

PURPOSE

To report the results of a prospective pilot study using a new heavy agent, HWS 46-3000, as long-term endotamponade in complicated retinal detachment.

METHODS

Thirty-two consecutive patients were enrolled in the study. Indications for enrollment included retinal detachment with proliferative vitreoretinopathy arising from inferior or posterior tears. The patients underwent pars plana vitrectomy, membrane peeling, and HWS 46-3000 filling. Follow-up examinations were scheduled at 1 day to 7 days and 1 month to 3 months after initial surgery and 7 days and 1 month to 6 months after endotamponade removal.

RESULTS

At baseline examination, mean best-corrected Snellen visual acuity was 2.44 logarithm of the minimal angle of resolution (logMAR). HWS 46-3000 was removed after 45 days to 96 days. Initial retinal reattachment was achieved in all eyes. HWS 46-3000 endotamponade was associated with a success rate of 84.6% with a single surgery and an overall success rate of 100% at 6 months with the second operation and conventional silicone oil endotamponade. At 6 months, mean best-corrected visual acuity was +1.09 logMAR (P < 0.0001). Complications were posterior subcapsular cataract formation (100%), membrane formation (3 eyes, 9%), and increased intraocular pressure (1 eye). Emulsification and intraocular inflammation were not observed.

CONCLUSION

HWS 46-3000 was well tolerated, effective in the inferior quadrants with a low incidence of membrane development. The main complication was the high rate of tamponade-related cataract formation.

Successful treatment of persistent macular holes using "heavy silicone oil" as intraocular tamponade

BACKGROUND

Silicone oil tamponade has been suggested in the treatment of persistent macular hole, but visual outcome is often poor. We describe two patients who underwent reoperation for persistent macular hole using "heavy silicone oil" (HSO) tamponade.

METHODS

Two patients who underwent vitrectomy, removal of the posterior vitreous cortex, peeling of the internal limiting membrane, and long-acting gas tamponade had persistent macular hole 3 months after surgery. The patients underwent reoperation using an HSO (Oxane Hd, Bausch & Lomb) as internal tamponade. This tamponade did not require postoperative posturing and was removed after 3 months. Optical coherence tomography (OCT) was performed, and visual outcome was determined.

RESULTS

OCT images showed that the HSO bubble conformed well with the retinal surface in the foveal region. Closure of the macular hole was achieved in both patients. Visual acuity increased from 20/100 to 20/40 in Patient 1 and from 20/600 to 20/100 in Patient 2.

CONCLUSION

HSO can be a useful tool in the treatment of persistent macular hole. OCT images showed that the tamponade was effective in the upright position in the foveal region. OCT allowed determination of the time of tamponade removal according to the anatomical stage of hole closure.

The combined use of perfluorohexyloctane (F6H8) and silicone oil as an intraocular tamponade in the treatment of severe retinal detachment

BACKGROUND

The purpose of this study was to investigate the combined use of perfluorohexyloctane (F6H8) and 1,000-centistoke silicone oil as a long-term intraocular tamponade in the treatment of complicated retinal detachment.

METHODS

Sixty consecutive eyes affected by complicated retinal detachment with (1) retinal breaks of the lower two quadrants and severe proliferative vitreoretinopathy, (2) inferior giant retinal tear, (3) penetrating trauma or (4) choroidal detachment underwent pars plana vitrectomy using a combined internal tamponade of F6H8 and silicone oil. The double filling (DF) was removed after 40-50 days. The anatomical outcome and the complications due to the DF are reported.

RESULTS

Retinal reattachment was achieved in all but one patient. Thirty-eight (63%) eyes needed further surgery with silicone oil tamponade. Silicone oil was successfully removed in 22 eyes. Sixteen (27%) eyes had retained silicone oil at the last follow-up examination. One eye showed persistent retinal detachment despite further surgery. Main complications of the DF were recurrent retinal detachment of the upper retina in six (10%) eyes and membrane formation in 25 (42%) eyes.

CONCLUSIONS

A combined internal tamponade of F6H8 and silicone oil may be a useful tool in the treatment of complicated retinal detachment involving the lower quadrants of the retina.

A pilot study on the use of silicone oil–RMN3 as heavier-than-water endotamponade agent

AIMS

This work was conducted to report an interventional non-comparative pilot study using Oxane HD, a mixture of ultra-purified silicone oil and RMN3, a partially fluorinated olefin, as heavier-than-water internal tamponade.

METHODS

Twenty-eight consecutive patients were recruited for this study. Indications included recurrent retinal detachment (RD) with proliferative vitreoretinopathy (PVR) (stage > or =C2) arising from inferior or posterior tears, recurrences after vitreoretinal surgery, penetrating trauma and combined rhegmatogenous and choroidal detachment. The patients underwent a pars plana vitrectomy, membrane peeling, and Oxane HD was used as long-term internal tamponade.

RESULTS

Oxane was removed after 88 days (range 45-96 days) and exchanged with BSS in five eyes, long-acting gas in 14 eyes and with silicone oil in nine eyes. Retinal reattachment was achieved in 15 eyes. The overall anatomical success rate obtained using Oxane HD was 53.5%. In 15 patients with previous marked scleral buckling, the success rate was 26%: in nine patients recurrent RD occurred in the inferior sector, in five patients new tears were detected in the lower sectors; membrane formation was observed in 15 eyes. In 13 patients without marked scleral indent, the success rate was 84.6%. There was no evidence of dispersion and excessive inflammation.

CONCLUSION

Oxane HD may be a useful tool in complicated RD with large inferior breaks, inferior PVR or combined rhegmatogenous, and choroidal detachment without marked scleral buckling, which put the eye profile out of shape, led to a higher failure rate and reduced the tamponading effectiveness of Oxane HD.

Perfluorocarbon-perfused vitrectomy: a new method for vitrectomy--a safety and feasibility study

PURPOSE

To evaluate the safety and feasibility of perfluorocarbon-perfused vitrectomy (PCPV) as a technique during vitrectomy for proliferative diabetic retinopathy (PDR) and rhegmatogenous retinal detachment (RRD).

METHODS

In an experimental, prospective, noncomparative and interventional study, 28 eyes of 28 patients were submitted to vitrectomy with the PCPV technique, 18 eyes with PDR and 10 with RRD. In this technique we replaced the traditional balanced saline solution (BSS) in the infusion line (conventional vitrectomy) by perfluorocarbon liquids (PCL). Some patients with PDR were treated with oxygenated PCL. Clinical evaluation, electroretinography (ERG), and endothelial cell count (ECC) were used to assess the safety of this procedure. An arbitrary grading system (grades 0-5) was used to classify the surgery and maneuvers to assess feasibility.

RESULTS

No eyes had a significant decrease in ECC, and the patients in whom we could obtain ERG postoperatively showed no significant differences from preoperative ERG. In the PDR group (using oxygenated and nonoxygenated PCL), 77.8% were graded 5/5; in the RRD group 90% were 5/5. PCPV allowed better visualization of vitreous and intraocular structures, rapid retinal reattachment, less blood in the vitreous cavity, subretinal fluid resolution, blood confinement, retinal stabilization, and easier dissection of epiretinal membranes. In all cases at least one surgical step was eliminated.

CONCLUSIONS

PCPV in humans is a safe and feasible technique. Probably in selected cases the use of PCL offers several advantages over BSS, because of their properties (gravitational forces, immiscibility with bodily fluids, and ability to transport oxygen). Prospective and comparative studies are necessary to establish formal indications and possible contraindications.

ADVERSE SIDE EFFECTS WITH PERFLUOROHEXYLOCTANE AS A LONG-TERM TAMPONADE AGENT IN COMPLICATED VITREORETINAL SURGERY

BACKGROUND

To report long-term intraocular tolerance of perfluorohexyloctane (F(6)H(8)).

METHODS

F(6)H(8) was used as an endotamponade in 18 patients (9 male and 9 female) with a median age of 65 years (range, 14-82 years) and complicated pathologic conditions of the inferior fundus: rhegmatogenous retinal detachment (17 patients) and tractional retinal detachment owing to proliferative diabetic retinopathy (1 patient). In six eyes, additional proliferative vitreoretinopathy was present. The use of F(6)H(8) was primary in 2 patients, and 16 patients had had previous retinal detachment surgery (median number, 2). F(6)H(8) was left in the eye for a median duration of 8 weeks (range, 2-14 weeks).

RESULTS

The median follow-up period was 6 months (range, 3-18 months). Permanent reattachment was achieved in 10 (56%) eyes after removal of F(6)H(8). In 8 (44%) of 18 eyes, a redetachment occurred. Two eyes became phthisic. Adverse side effects included photophobia in two patients, pain in two, hypotony in four, early emulsification in one, corneal lesion in one, fibrinous membranes in five, posterior lens opacification in one, and retinal scar formation in one.

CONCLUSION

Perfluorohexyloctane provides good support to the inferior retina. Because of numerous adverse side effects, it should be considered carefully when used as a long-term tamponade. Early removal may reduce the number of side effects.

Our experience with perfluorohexyloctane (F6H8) as a temporary endotamponade in vitreoretinal surgery

PURPOSE

To evaluate the use of F6H8 as a temporary endotamponade for complicated and special cases of retinal detachment instead of silicone oil.

METHODS

We have used F6H8 with 14 patients since February 1999. Eight suffered from rhegmatogenous retinal detachment (RRD) with multiple tears located inferiorly. Three presented inferior traction retinal detachment (TRD) under silicone oil, two suffered from ocular trauma with inferior TRD, and one had idiopathic macular hole. The substance was introduced into the eye after pars plana vitrectomy and membrane peeling if needed, and we tried to introduce as much as possible.

RESULTS

With F6H8 the retina was easily reattached in all cases, like with perfluorocarbon liquids. The postoperative view was very good. F6H8 was removed in all cases after 3-8 weeks. Anatomical success was achieved in 12 out of 14 eyes. Two eyes presented severe PVR. F6H8 entered the anterior chamber in 4 cases, but no corneal complications occurred. In one case there was a marked IOP rise due to an anterior block, treated with superior iridotomy. In two cases retinal detachment (RD) occurred in the upper part and was treated with additional surgery, F6H8 removal and silicone oil injection.

CONCLUSIONS

F6H8 seems to be a promising tamponade agent for special cases of RD.