Intravitreal Fluorinated Gas Preference and Occurrence of Rare Ischemic Postoperative Complications after Pars Plana Vitrectomy: A Survey of the American Society of Retina Specialists

A Short-Time Real-World Study of Two Perfluoropropane Tamponade Methods in Pars Plana Vitrectomy for Retinal Detachment

INTRODUCTION

This real-world study evaluated the efficacy, safety, and operative parameters of two perfluoropropane (C3F8) tamponade methods combined with pars plana vitrectomy (PPV) for retinal detachment (RD).

METHODS

A retrospective study of 132 patients (132 eyes) with RD (pure C3F8 in 38 eyes, mixed C3F8 in 94 eyes). All eyes underwent PPV with C3F8 tamponade and were followed up for at least 3 months. Retinal reattachment rate, time of gas configuration and injection, C3F8 dosage, intraocular pressure (IOP), best corrected visual acuity, postoperative ocular inflammation, and patients' complaints were evaluated.

RESULTS

The single-surgery retinal reattachment rates of the pure C3F8 group and mixed C3F8 group were 97.4% and 96.8%, respectively, with no significant difference (p = 1.00). The final retinal reattachment rates of the two groups were 100% and 97.2%, respectively, with no significant difference (p = 1.00). The gas configuration time, gas injection time, and C3F8 dosage were significantly less in the pure C3F8 group (all p < 0.001). Time, but not group, was the influencing factor of postoperative IOP changes in the two groups (p < 0.001, p = 0.547, respectively). Compared with the baseline, the IOP estimates of the pure C3F8 group showed a significant increase immediately after surgery (p < 0.001), and the mixed C3F8 group showed a significant increase immediately and 1-2 days after surgery (all p < 0.05). There was no statistical difference in ocular inflammation (p = 0.339) and patients' complaints of discomfort (p = 0.175) between the two groups.

CONCLUSION

Both the two methods of C3F8 tamponade combined with PPV in RD patients showed good efficacy and safety, but the clinical operation of pure C3F8 tamponade was more convenient and eco-friendly.

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.

Comparison between air and gas as tamponade in 25-gauge pars plana vitrectomy for primary superior rhegmatogenous retinal detachment

BACKGROUND/OBJECTIVES

The aim of this study was to compare surgical outcomes and postoperative characteristics, between eyes that underwent pars plana vitrectomy (PPV) for RRD, with air or different gas agents as tamponade.

SUBJECTS/METHODS

The records of 262 patients that underwent PPV for RRD with air or different gas tamponades and a follow-up of at least 6 months were examined. Only cases with superior retinal breaks were included. Demographic, pre-, intra- and postoperative characteristics including rate of recurrence and complications were analysed.

RESULTS

48 patients were treated with air and 214 were treated with gas. No differences were found in success rate between air and gas group at both 3 and 6 months (respectively, 93.8% vs 93.6 and 100% vs 100%, all P values > 0.05). Postoperative best-corrected visual acuity (BCVA) was significantly higher in the air group compared with the gas group 7 days and 1 month postoperatively (respectively, 0.2 ± 0.4 vs 2.6 ± 0.5, P < 0.001 and 0.1 ± 0.4 vs 0.4±0.9, P = 0.04). The occurrence ocular hypertension at 1 month postoperatively was significantly higher in the gas group compared with the air group (15.4 % vs 0%, P < 0.001). At 6 months, the prevalence of epiretinal membrane (ERM) was significantly higher in the gas group compared with air group (4.2% vs 16.8%, P = 0.02).

CONCLUSIONS

Air was comparable to gas tamponades in terms of surgical outcome and BCVA at 6 months. In addition, air allowed an earlier visual recovery and resulted in a lower rate of postoperative ocular hypertension and ERM.

Gas Expansion Three Days after Pars Plana Vitrectomy with Sulfur Hexafluoride 20% Tamponade following Carbon Monoxide Toxicity and Oxygen Therapy

Purpose

To report an unusual case of gas expansion following oxygen therapy in a patient with sulfur hexafluoride (SF₆) 20% tamponade after pars plana vitrectomy. Case Report. A 40-year-old man came to the clinic with severe ocular pain and redness and also vision decrease in his left eye three days after uncomplicated 23-gauge pars plana vitrectomy, internal limiting membrane peeling combined with phacoemulsification, and using 20% SF₆ injection as a tamponade agent due to significant cataract and a full-thickness macular hole. In ophthalmic examinations of his left eye, high intraocular pressure (approximately 70 mmHg), a flat anterior chamber, and a gas-filled vitreous cavity were found. The patient had been hospitalized the day before due to carbon monoxide poisoning and had undergone oxygen therapy with a pure 100% mask for three hours.

Conclusion

It seems that oxygen therapy or carbon monoxide poisoning increases the volume of gas in the patient's vitreous cavity and the nonexpansile percentage of SF₆ expands.

Current Situation and Challenges in Vitreous Substitutes

Vitreo-retinal disorders constitute a significant portion of treatable ocular diseases. These pathologies often require vitreo-retinal surgery and, as a consequence, the use of vitreous substitutes. Nowadays, the vitreous substitutes that are used in clinical practice are mainly divided into gases (air, SF₆ , C₂ F₆ , C₃ F₈ ) and liquids (perfluorocarbon liquids, silicone oils, and heavy silicone oils). There are specific advantages and drawbacks to each of these, which determine their clinical indications. However, developing the ideal biomaterial for vitreous substitution continues to be one of the most important challenges in ophthalmology, and a multidisciplinary approach is required. In this sense, recent research has focused on the development of biocompatible, biodegradable, and injectable hydrogels (natural, synthetic, and smart), which also act as medium and long-term internal tamponade agents. This comprehensive review aims to cover the main characteristics and indications for use of the extensive range of vitreous substitutes that are currently used in clinical practice, before going on to describe the hydrogels that have been developed recently and which have emerged as promising biomaterials for vitreous substitution.

INTRAOCULAR APPLICATION OF FIBRIN GLUE AS AN ADJUNCT TO PARS PLANA VITRECTOMY FOR RHEGMATOGENOUS RETINAL DETACHMENT

PURPOSE

To evaluate the efficacy of intraocular application of fibrin glue to seal the retinal breaks during standard pars plana vitrectomy for primary rhegmatogenous retinal detachment.

METHODS

Twenty-six eyes of 26 rhegmatogenous retinal detachment patients were included in the study. Fibrin glue was used to seal the retinal breaks during standard pars plana vitrectomy in all 26 eyes. Each eye was completely filled with a balanced saline solution at the end of the surgery. The success rate of the reattachment surgery, change in best-corrected visual acuity, intraocular pressure, and occurrence of intraoperative and postoperative complications were recorded and analyzed.

RESULTS

All eyes, with a mean age of 45.1 ± 18.3 years, were treated with pars plana vitrectomy surgery. During pars plana vitrectomy surgery, the fibrin glue showed excellent adherence and compliance to the retina. The glue was no longer visible through ultrasound scan 14.85 ± 4.56 days after surgery. The retinal breaks were sealed completely, and retina attached in all 26 eyes with no occurrence of rhegmatogenous retinal detachment during the follow-up period. The best-corrected visual acuity at 6 months after operation was significantly improved from preoperation best-corrected visual acuity. After operation, two eyes (2/26) developed an epiretinal membrane. Although three eyes (3/26) had a transient increased intraocular pressure during the 1st week after surgery, the intraocular pressure lowered to the normal range after the application of timolol. One eye (1/26) required daily topical antiglaucoma drops to lower the intraocular pressure. No adverse effects of fibrin glue were observed.

CONCLUSION

The fibrin glue provided a superior adhesive effect for sealing retinal breaks, while showing no additional adverse effects. It is a worthy alternative to gas tamponade for rhegmatogenous retinal detachment vitrectomy surgery.

Vitreous substitutes: An overview of the properties, importance, and development

Vitreous or vitreous humor is a complex transparent gel that fills the space between the lens and retina of an eye and acts as a transparent medium that allows light to pass through it to reach the photoreceptor layer (retina) of the eye. The vitreous humor is removed in ocular surgery (vitrectomy) for pathologies like retinal detachment, macular hole, diabetes-related vitreous hemorrhage detachment, and ocular trauma. Since the vitreous is not actively regenerated or replenished, there is a need for a vitreous substitute to fill the vitreous cavity to provide a temporary or permanent tamponade to the retina following some vitreoretinal surgeries. An ideal vitreous substitute could probably be left inside the eye forever. The vitreous humor is transparent, biocompatible, viscoelastic and highly hydrophilic; polymeric hydrogels with these properties can be a potential candidate to be used as vitreous substitutes. To meet the tremendous demand for the vitreous substitute, many scientists all over the world have developed various kinds of vitreous substitutes or tamponade agent. Vitreous substitutes, whatsoever developed till date, are associated with several advantages and disadvantages, and there is no ideal vitreous substitute available till date. This review highlights the polymer-based vitreous substitutes developed so far, along with their advantages and limitations. The gas-based and oil-based substitutes have also been discussed but very briefly.

Objective analysis of perfluoropropane tamponade area after pars plana vitrectomy using ultra-widefield fundus stereographic projection images

To objectively analyze the gas tamponade area in patients with different concentrations of perfluoropropane (C₃F₈) after pars plana vitrectomy (PPV), retrospective analysis was performed in patients diagnosed with retinal detachment or macular hole and underwent PPV with C₃F₈ tamponade of two concentrations (14% and 20%). The ultra-widefield fundus (UWF) images at one and 10 days and four weeks postoperatively were corrected using stereographic projection to adjust peripheral distortion. The gas-fluid interface curvatures were delineated using UWF stereographic projection images, and the gas-fluid area ratio and estimated gas area were calculated at each concentration. Among 65 eyes, 30 were in the 14% group and 35 were in the 20% group. The gas-fluid area ratio was 0.71 in the 14% group and 0.83 in the 20% group at 10 days (p = 0.046) and 0.27 and 0.45, respectively, at four weeks postoperatively (p < 0.001). The estimated gas area was 52.56 and 60.82 mm² at 10 days (p = 0.025) and 19.83 and 33.86 mm² at four weeks (p < 0.001). The gas tamponade areas were objectively shown to be greater under the 20% concentration than the 14% concentration of C3F8 at 10 days and 4 weeks postoperatively using UWF stereographic projection images.

19 F MRI of human lungs at 0.5 Tesla using octafluorocyclobutane

PURPOSE

The aim of this study was to demonstrate the feasibility of fluorine-19 (¹⁹ F) MRI of the human lungs using octafluorocyclobutane (OFCB, C₄ F₈ ). This gas has 8 magnetically equivalent fluorine nuclei and relatively long T₁ and T₂ (˜50 ms), which render it suitable as an MRI contrast agent. Previous experiments in small laboratory animals showed that OFCB could be successfully used as an alternative to the gases often used for ¹⁹ F MRI (sulfur hexafluoride and perfluoropropane).

METHODS

One male volunteer participated in this study. Immediately before an MRI scan, the volunteer inhaled the gas mixture-80% OFCB with 20% oxygen-and held his breath. Experiments were performed on a 0.5T whole-body MR scanner with a customized transmit-receive coil tuned at ¹⁹ F frequency. Fast spin echo in 2D and 3D modes was used for image acquisition. 2D images were obtained with in-plane resolution of 10 × 10 mm² without slice selection. 3D images were obtained with the voxel size of 10 × 10 × 30 mm² . Breath-hold duration was 20 s for 2D and 40 s for 3D imaging, respectively.

RESULTS

Anatomically consistent ¹⁹ F MR images of the human lungs were obtained with SNR around 50 in 2D mode and 20 in 3D mode. 3D volumetric images of the lungs were reconstructed and provided physiologically reasonable volume estimates.

CONCLUSION

The application of OFCB enables informative ¹⁹ F lung imaging even at low magnetic field strengths. The OFCB gas shows promise as an inhalable contrast agent for fluorine lung MRI and has a potential for clinical translation.

Measurement of the volume of the vitrectomized space during vitrectomy in myopic patients with retinal detachment

PURPOSE

We present a novel technique for measuring volume of space replaced by air during fluid-air exchange in vitrectomy (vitrectomized space) for intravitreal gas injection. To confirm the feasibility of this technique, we assessed postoperative intraocular pressure (IOP) and the duration of injected gas. Using this technique, we found remarkable differences in volume between high myopic eyes with retinal detachment caused by peripheral break (PB-RD group) and those with macular hole retinal detachment (MH-RD group). We studied the relationships between the volume and biometric values, axial length (AL) and corneal curvature radius (CCR) in both PB-RD and MH-RD group.

STUDY DESIGN

Retrospective study.

METHODS

During fluid-air exchange, the aspirated fluid accumulates in the measuring cup between the infusion needle and vitrectomy instrument. Vitrectomized space volume is obtained by subtracting the volume of the tube between the infusion needle and the 3-way stopcock from the aspirated fluid volume. We performed phaco-vitrectomies by measuring the vitrectomized space volume and then injected pure SF6 at 15% of the volume into the vitreous cavity in 156 myopic eyes (AL > 26 mm) with RD consisting of 144 eyes in PB-RD group and 12 in MH-group.

RESULTS

The IOP (mean ± SD) was 13.5 ± 3.4 mmHg preoperatively, 23.4 ± 10.4 mmHg on day 1, 18.2 ± 7.4 mmHg on day 2, and 16.1 ± 4.5 on day 7. The gas disappeared in 16.1 ± 1.9 days. Axial length was longer in the MH-RD group but the volume of vitrectomized space was larger in the PB-RD group. AL and volume were significantly correlated in both groups (P < 0.01), but the fitting lines differed. The CCR and volume significantly correlated in the PB-RD group (P < 0.01) but not in the MH-RD group.

CONCLUSION

Our novel technique for measuring the volume of vitrectomized space can achieve target gas concentration in the vitreous cavity. The difference in the shape of eyeballs may explain discrepancies in relationship between volume and the biometric factors.

NECROSIS OF THE RETINA AND UVEAL TRACT SECONDARY TO EXPANDING GAS TAMPONADE

PURPOSE

To present a case of retinal and uveal necrosis caused by expanding gas tamponade after pars plana vitrectomy.

METHODS

Single case report.

RESULTS

An otherwise healthy 66-year-old woman underwent pars plana vitrectomy with intended 20% sulfur hexafluoride (SF6) tamponade for macular hole repair of her pseudophakic left eye. She developed intractable nausea, emesis and increasing left eye pain in association with gas expanded to totally fill the left eye, just hours after surgery. Extremely elevated intraocular pressure was lowered with a successful paracentesis but recurred within a few hours. She then underwent vitrectomy evacuation of all vitreous cavity gas, reformation of the anterior chamber, and silicone oil placement, normalizing intraocular pressure. Three weeks later, the left eye had no light perception, and devitalization of the retina, choroid, and iris was evident.

CONCLUSION

We present a case of blindness and intraocular tissue dissolution/disorganization after vitrectomy with intended 20% SF6. To our knowledge, this is the most detailed report of the under-recognized complication of expanding gas tamponade. Institutions hosting vitrectomy surgery should consider enacting a formal "Time Out" that requires all team members to witness accurate fractionation of potentially expansile gas. In the event of acute postoperative glaucoma in such eyes, a single small volume paracentesis cannot be relied upon to protect against continued gas expansion.

Complications Associated with the Use of Expandable Gases in Vitrectomy

Intraocular gases have been used in vitreoretinal surgery for over 40 years. The aim of this study was to review the complications related to the use of expandable gases in vitrectomy and their management. A PubMed, Cochrane Library, and Embase search was conducted using the terms "intraocular gas" and "vitrectomy for retinal detachment." Of the articles retrieved by this method, all publications in English and abstracts of non-English publications were reviewed. Intraocular pressure elevation was reported in up to 58.9% patients after vitrectomy with expandable gas administration for retinal detachment. Vitreoretinal surgery is known to induce cataract development. With that, cataract progression is associated with lens exposure to intraocular gas, the duration of such exposure, patient's age, and the magnitude of vitreous removal. With intraocular gas, the posterior surface of the lens becomes a strongly refractive factor, resulting in high myopia and temporary vision impairment. Other complications related to the use of expandable gases include anterior chamber and subconjunctival gas displacement. Single reports on subretinal and cranial gas migration were published. In vitrectomy for uncomplicated retinal detachments, attempts to shift from expandable gases towards air are observed. Nevertheless, gas tamponade remains a reasonable choice for patients suffering from retinal detachment.

THEORETICAL GAS CONCENTRATIONS ACHIEVING 100% FILL OF THE VITREOUS CAVITY IN THE POSTOPERATIVE PERIOD: A Gas Eye Model Study

PURPOSE

To determine the concentrations of different gas tamponades in air to achieve 100% fill of the vitreous cavity postoperatively and to examine the influence of eye volume on these concentrations.

METHODS

A mathematical model of the mass transfer dynamics of tamponade and blood gases (O2, N2, and CO2) when injected into the eye was used. Mass transfer surface areas were calculated from published anatomical data. The model has been calibrated from published volumetric decay and composition results for three gases sulphahexafluoride (SF6), hexafluoroethane (C2F6), or perfluoropropane (C3F8). The concentrations of these gases (in air) required to achieve 100% fill of the vitreous cavity postoperatively without an intraocular pressure rise were determined. The concentrations were calculated for three volumes of the vitreous cavity to test whether ocular size influenced the results.

RESULTS

A table of gas concentrations was produced. In a simulation of pars plana vitrectomy operations in which an 80% to 85% fill of the vitreous cavity with gas was achieved at surgery, the concentrations of the 3 gases in air to achieve 100% fill postoperatively were 10% to 13% for C3F8, 12% to 15% for C2F6, and 19% to 25% for SF6. These were similar to the so-called "nonexpansive" concentrations used in the clinical setting. The calculations were repeated for three different sizes of eye. Aiming for an 80% fill at surgery and 100% postoperatively, an eye with a 4-mL vitreous cavity required 24% SF6, 15% C2F6, or 13% C3F8; 7.2 mL required 25% SF6, 15% C2F6, or 13% C3F8; and 10 mL required 25% SF6, 16% C2F6, or 13% C3F8. When using 100% gas (e.g., used in pneumatic retinopexy), to achieve 100% fill postoperatively, the minimum vitreous cavity fill at surgery was 43% for SF6, 29% for C2F6, and 25% for C3F8 and was only minimally changed by variation in the size of the eye.

CONCLUSION

A table has been produced, which could be used for surgical innovation in gas usage in the vitreous cavity. It provides concentrations for different percentage fills, which will achieve a moment postoperatively with a full fill of the cavity without a pressure rise. Variation in axial length and size of the eye does not seem to alter the values in the table significantly. Those using pneumatic retinopexy need to increase the volume of gas injected with increased size of the eye to match the percentage fill of the vitreous cavity recommended for a given tamponade agent.

Nanomedicine in the application of uveal melanoma

Rapid advances in nanomedicine have significantly changed many aspects of nanoparticle application to the eye including areas of diagnosis, imaging and more importantly drug delivery. The nanoparticle-based drug delivery systems has provided a solution to various drug solubility-related problems in ophthalmology treatment. Nanostructured compounds could be used to achieve local ocular delivery with minimal unwanted systematic side effects produced by taking advantage of the phagocyte system. In addition, the in vivo control release by nanomaterials encapsulated drugs provides prolong exposure of the compound in the body. Furthermore, certain nanoparticles can overcome important body barriers including the blood-retinal barrier as well as the corneal-retinal barrier of the eye for effective delivery of the drug. In summary, the nanotechnology based drug delivery system may serve as an important tool for uveal melanoma treatment.

Outcome of 2 cc pure sulfur hexafluoride gas tamponade for macular hole surgery

Background

Isoexpansile concentrations of intraocular gases are typically used as tamponading agent in macular hole surgery. Using a small volume of the pure form of these gases may achieve the same result without increasing the incidence of postoperative complications. The purpose of this study was to evaluate the anatomical and visual outcomes following macular hole surgery with 2 cc pure (100 %) sulfur hexafluoride (SF₆) gas tamponade.

Methods

A retrospective study of eyes with idiopathic macular holes that underwent 23-gauge pars plana vitrectomy with 2 cc pure SF₆ gas tamponade. Macular hole surgery was performed alone or in combination with phacoemulsification in eyes with cataract. Preoperative and postoperative data including best corrected visual acuity recorded in LogMAR units, slit-lamp biomicroscopy, and optical coherence tomography were analysed. Surgical complications were also recorded.

Results

Seventy six eyes of seventy five patients were analysed. A closure rate of 100 % was achieved with reoperation in 4 eyes. There was a significant improvement in best-corrected visual acuity from a mean of 0.65 LogMAR preoperatively to 0.36 at 6 months (p value 0.004). Forty five (59 %) eyes gained at least 2 lines on the Snellen visual acuity chart. Postoperative elevation in intraocular pressure (≥30 mmHg) was documented in 3 eyes (4 %).

Conclusion

Macular hole surgery with 2 cc pure SF₆ gas tamponade achieved a high success rate with a low incidence of complications. The smaller volume of gas required makes it a cheaper technique.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0254-9) contains supplementary material, which is available to authorized users.

Paul Sullivan: catalyst in the history and use of intraocular sulfur hexafluoride

The use of air to attempt to reattach the retina dates back to 1909. However, despite the widespread use of intraocular air in the 1950s and 1960s, retinal surgeons struggled with the main limitation of the device (ie, the relatively short duration of the gas within the vitreous cavity). Fortuitous events in the late 1960s allowed Paul Sullivan, MD, to introduce the first expansile gas, sulfur hexafluoride, to Edward W.D. Norton, MD, and his colleagues at the University of Miami. The use of sulfur hexafluoride helped revolutionize retinal detachment surgery and allowed for further advances in treating other posterior segment diseases.

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.

Update on retinal detachment surgery

PURPOSE OF REVIEW

Update on controversies in the surgical management of rhegmatogenous retinal detachment.

RECENT FINDINGS

There are multiple new reports regarding the development and management of retinal detachment. Current use of oral fluoroquinolones may be associated with onset of retinal detachment, although the clinical relevance of this correlation is uncertain at this time and the finding has not been replicated in subsequent studies. Pars plana vitrectomy (PPV) continues to demonstrate efficacy as a primary treatment for retinal detachment, especially in pseudophakic patients. In many patients with macula-on retinal detachment, scheduling surgery after a short time delay is not necessarily deleterious and may actually be beneficial. Novel surgical tools, including bioerodible scleral buckling materials and artificial vitreous substitutes, are being investigated.

SUMMARY

Retinal detachment remains an important cause of visual loss. Although current surgical techniques demonstrate high rates of anatomic and visual success, further advances will probably benefit patients with retinal detachment.