Perfluoro-n-octane Research Articles

Use of Cohesive Viscoelastic Agents to Facilitate Safe Removal of Posterior Segment Intraocular Foreign Bodies.

Purpose: To assess the ability of viscoelastic agents and perfluoro-N-octane (PFO) to safely remove an intraocular foreign body (IOFB). Methods: A 23-gauge pars plana vitrectomy and lensectomy were performed in a porcine eye. A 5.0 mm metallic IOFB was inserted through a corneal paracentesis and dropped into the vitreous cavity. The posterior segment was filled completely with a balanced salt solution, cohesive viscoelastic, or dispersive viscoelastic or partially filled with PFO under a balanced salt solution. The IOFB was then brought anteriorly and released. Each test was repeated multiple times and videorecorded. Results: The IOFB fell with high velocity through the balanced salt solution-filled vitreous cavity. When the eye was filled with either of the 2 viscoelastic agents, the IOFB did not move or moved posteriorly extremely slowly. A vitreous cavity filled partially with PFO led to deflection of the object's path, with the peripheral retina being struck, or the IOFB dropping straight down and striking the macula. PFO and the cohesive viscoelastic were easily removed from the eye with the vitrectomy instrument. The dispersive viscoelastic could not be completely removed and repeatedly clogged the vitreous cutter. Conclusions: Filling the posterior segment with a cohesive viscoelastic agent may significantly increase the safety and ease of IOFB removal.

Cost Drivers of Pars Plana Vitrectomy for Retinal Detachment: Time-Driven Activity-Based Costing Analysis.

Introduction: To determine drivers of day-of-surgery costs for pars plana vitrectomy (PPV) in the management of retinal detachment (RD) repair, the mainstay treatment, based on surgical complexity and intraoperative factors. Methods: Economic analysis was performed using time-driven activity-based costing methodology for patients who had standard (Current Procedural Terminology [CPT] code 67108) or complex (CPT 67113) RD repair with PPV at the University of Michigan in 2021. Data were obtained via the electronic health record and previous literature. PPV expenses were determined with time-driven activity-based costing, a cost calculation that incorporates time and key resource costs, and were analyzed using univariate and multivariate regression. Results: The analysis included 412 PPVs (270 standard and 142 complex based on CPT code). The operating room time was significantly increased in complex cases (P < .01). Univariate analysis found that complex PPV, cryopexy, staining agent use, retinectomy, simultaneous scleral buckling, perfluoro-N-octane (PFO) use, silicone oil tamponade, and perfluoropropane tamponade were associated with a statistically significant difference in costs (P < .01); use of laser retinopexy was not significantly associated (P = .7190). Multivariate analysis found that standard PPV cost an average $5132.33 and significant incremental costs were found for complex PPV (+$1185.55; P < .001), cryopexy (+$465.02; P = .032), staining (+$525.16; P = .04), PFO use (+$1089.54; P < .0001), retinectomy (+$2031.17; P < .0001), and simultaneous scleral buckling (+$916.34; P = .006). Conclusions: The intraoperative factors that increase operating room time and ultimately the incurred cost of complex PPV cases vs standard PPV were identified and economically defined. These findings can improve practice patterns by optimizing costs for effective surgical planning in the management of RD repair.

Pars plana vitrectomy for retinal detachment using perfluoro-n-octane as intraoperative tamponade: a multicenter, randomized, non-inferiority trial.

To evaluate the efficacy and safety of perfluoro-n-octane (PFO) for ophthalmic surgery versus F-Octane as an intraoperative tamponade in pars plana vitrectomy (PPV) in management of retinal detachment. This multicenter, prospective, randomized, double-masked, parallel-controlled, non-inferiority trial was conducted in three ophthalmology clinical centers in China. Patients with retinal detachment, who were eligible for PPV were consecutively enrolled. Participants were assigned to PFO for ophthalmic surgery or F-Octane for intraocular tamponade in a 1:1 ratio. Best-corrected visual acuity (BCVA), intraocular pressure (IOP) measurement, and dilated fundus examination were performed preoperatively and at 1, 7±1, 28±3d postoperatively. The primary outcome was complete retinal reattachment rate at postoperative day one. The non-inferiority margin was set at 9.8%. The secondary outcomes included intraoperative retinal reattachment rate, and mean changes in IOP and BCVA from baseline to 1, 7±1, 28±3d postoperatively, respectively. Safety analyses were presented for all randomly assigned participates in this study. Totally 124 eligible patients completed the study between Mar. 14, 2016 and Jun. 7, 2017. Sixty of them were randomly assigned to the PFO for ophthalmic surgery group, and 64 were assigned to the F-Octane group. Baseline characteristics were comparable between the two groups. Both groups achieved 100% retinal reattachment at postoperative day one (difference 0, 95%CI: -6.21% to 5.75%, P=1). The pre-defined noninferiority criterion was met. No significant difference was observed in intraoperative retinal reattachment rate (difference 1.77%, P=0.61), mean changes in IOP (difference 0.36, -0.09, 2.22 mm Hg at 1, 7±1, 28±3d postoperatively, with all P>0.05) and BCVA (difference 0.04, -0.02, 0.06 logMAR at 1, 7±1, 28±3d postoperatively, all P>0.05) between the two groups. No apparent adverse events related to the utilization of PFO were reported. In patients with retinal detachment undergoing PPV, PFO for ophthalmic surgery is non-inferior to F-Octane as an intraocular tamponade, and both are safe and well-tolerated.

Perfluoro-n-octane-assisted Superior Inverted ILM Flap without Using the Peeling-off Technique for Large Macular Holes

Purpose: To evaluate the surgical outcomes of a perfluoro-n-octane (PFO)-assisted superior inverted internal limiting membrane (ILM) flap without the peeling-off technique for the treatment of a large macular hole (MH).Methods: This retrospective interventional case series examined 13 eyes with a MH ≥ 400 μm. All eyes underwent 25-gauge pars plana vitrectomy. An ILM flap stained with 0.025% brilliant blue G was made in the superior area of the hole. The ILM in the temporal, nasal, and inferior areas around the hole was not peeled off. The hole was gently covered using the inverted ILM flap, which was stabilized using a small amount of PFO. Fluidair exchange was performed slowly. The small amount of residual PFO was removed by evaporation. The patients were instructed to maintain a facedown position for 1 day postoperatively. Anatomical closure of the hole and visual acuity were assessed postoperatively.Results: The average hole size was 605.08 ± 102.41 μm. Nine eyes had an idiopathic MH, two exhibited age-related macular degeneration, and one each had high myopia and a traumatic MH. All eyes achieved type I closure. The foveal contour improved gradually during follow-up: 92.3% of eyes had a U-shaped fovea, and 61.5% exhibited complete recovery of the ellipsoid zone. The visual acuity improved from 0.91 to 0.55 logarithm of the minimum angle of resolution (&lt;i&gt;p&lt;/i&gt; = 0.003).Conclusions: The PFO-assisted superior inverted ILM flap without peeling-off was effective for stabilizing the flap over the hole and consequently achieving good anatomical and visual outcomes in large MHs.

Comparison of Perfluorocarbon Liquids Cytotoxicity Tests: Direct Contact Versus the Test on Liquid Extracts.

The purpose of this study is to compare the in vitro cytotoxicity tests according to the ISO 10993-5 (2009) standards using direct contact and the test on liquid extracts of compounds previously identified as possible toxic impurities in perfluorocarbon liquids (PFCLs) for use in vitreoretinal surgery. Compounds including perfluorooctanoic acid (PFOA), 1H-perfluorooctane (1H-PFO), 2H-tridecafluoro-2-methylpentane, 1H,2H-octafluorocyclopentane, and 2H,3H-decafluoropentane were analyzed by 19F NMR before and after extraction using an aqueous solution and tested by both the direct contact and liquid extract tests in L929, BALB 3T3, and ARPE-12 cells. The concentration that reduced in vitro cell viability by 30%, the cytotoxicity concentration threshold (CC30), was determined for each compound. 19F NMR spectroscopy confirmed the immiscibility of perfluoro-n-octane (PFO) and 1H-PFO and the solubility of PFOA with the extraction vehicle. The other samples reacted with the extraction vehicle, releasing fluoride ions. Using the direct contact test, the CC30 of PFOA, 1H-PFO, 2H-tridecafluoro-2-methylpentane, 1H,2H-octafluorocyclopentane, and 2H,3H-decafluoropentane corresponded to 48 124, 50, 14, 8035, and 46 ppm, respectively. The method on liquid extracts did not detect cytotoxicity in three out of five tested compounds, and CC30 could not be determined. In conclusion, the in vitro cytotoxicity test by direct contact revealed a positive correlation between cell toxicity and the concentration of the tested substance. Conversely, the test on liquid extracts hardly detected the cytotoxicity of toxic impurities in PFCLs. Thus, only the cytotoxicity test by direct contact, according to ISO 10993-5 (2009), is a sensible and reliable method to detect possible cytotoxic impurities in PFCLs to guarantee patient safety.

Scleral rupture during micro-incision vitrectomy surgery for primary rhegmatogenous retinal detachment - A case report

Scleral rupture during 23-gauge pars plana vitrectomy (PPV) for primary rhegmatogenous retinal detachment, without known predisposing factors, is a rare but catastrophic complication. Scleral rupture in our patient developed in superotemporal quadrant corresponding to the area of chorioretinal atrophy in retina. Prompt suturing of scleral rupture, usage of perfluoro-N-octane (PFO) as short-term endo-tamponade, and removal of epiretinal membrane (ERM) under silicone oil (SO) were the major contributing factors leading to successful outcome. High index of suspicion should be kept for any chorioretinal atrophic patches and sclera corresponding to these areas should be carefully examined for any pathosis.

Intraoperative findings and postoperative results associated with cataract surgery performed after retinal reattachment surgery in dogs-36 cases (41 eyes).

To report intraoperative findings and complications associated with cataract surgery performed after retinal reattachment surgery (RR) via pars plana vitrectomy (PPV) using perfluoro-n-octane (PFO), laser retinopexy, and silicone oil tamponade in dogs. Retrospective record review of dogs that underwent post-RR cataract surgery. Signalment, time between RR and cataract surgery, type of lens extraction, postoperative visual status, and intra- and postoperative complications were recorded. Cataract formation or progression after RR was categorized as early (≤12months) or late (>12months). A total of 36 dogs (41 eyes) were included. Average time between RR and cataract surgery was 665days (median: 546). Early postoperative incidence of cataracts occurred in 19 eyes (46.3%). Types of lens extraction included phacoemulsification with intraocular lens (86.1%, 31/36 dogs), phacoemulsification alone (11.1%, 4/36 dogs), and intracapsular lens extraction (2.8%, 1/36 dogs). Visual improvement occurred in 95.1% of eyes (39/41) immediately postoperatively. Long term, 93.9% of eyes (31/33) maintained vision at 1month, 85.2% of eyes (23/27) at 3months, 77.3% of eyes (17/22) at 6months, and 60% (12/20) at 12months postoperatively. The most common postoperative complications were glaucoma (29.3%, 12/41 eyes), corneal ulceration (24.4%, 10/36 eyes), fibrin formation (21.9%, 9/41 eyes), and silicone oil migration into the anterior chamber (19.5%, 8/41 eyes). Post-RR cataract surgery should be considered in dogs with vision loss from cataracts after RR. In most eyes, vision was maintained up to 1year postoperatively.

Successful Technique for Closure of Macular Hole Retinal Detachment Using Autologous Retinal Transplant

Macular hole retinal detachment (MHRD) for the most part develops in highly myopic eyes. Several surgical methods have been introduced to treat MHRD. We describe our experience with the autologous retinal transplant in patient with MHRD. A 49-year-old female presented with a 2-week history of a sudden decrease in the central vision in the right eye (RE). A 3-port, 25-gauge pars plana vitrectomy was performed with the ILM dye staining and peeling. Endodiathermy was applied around a 1.5-disc diameter neurosensory donor site in the supertemporal retina. The graft was cut with standard 25-gauge curved scissors. Perfluoro-n-octane (PFO) was instilled. The free graft was gently handled until its packing into the macular hole. Two months following the initial PPV, the macular hole was closed, and vision improved from 0.05 to 0.25 logMAR.

Optic coherence tomography features of subretinal vitreous substitutes

BackgroundTo draw comparisons between spectral domain optic coherence tomography (SD-OCT) features of subretinal silicon oil (SO), perfluoro-n-octane (PFO) or C3F8 gas.MethodsCases diagnosed with retained subretinal vitreous substitutes (VS) were retrospectively selected. Demographic data were collected and OCT features were analyzed.ResultsIn the 13 cases with subretinal PFO, hyper-reflectivity under the bubble was noted in 8 eyes (61.5%); choroidal shadow at the borders of the bubble in 11 eyes (84.6%); hyper-reflective halo around the bubble in 5 eyes (38.4%) and a hyper-reflective apical dot in 8 eyes (61.5%).The two cases with multiple PFO bubbles had complete septum dividing the bubbles. The one case with subretinal SO had hyper reflectivity under the bubble; no choroidal shadow at the edge of the bubble; hyper-reflective halo was noted around the bubble and the apical hyper-reflective dot was present; there was no complete septum dividing multiple bubbles. The single case with subretinal C3F8 had some bubbles with totally round base, incomplete septum, hyper reflectivity under the bubble, choroidal shadow at the edge of the bubble, a hyper-reflective halo and an apical dot.ConclusionDifferent subretinal VS share similar SD-OCT characteristics. Round base bubbles are only observed with subretinal C3F8 gas, while incomplete septum are related to retained subretinal SO or gas.

PFOh No: Spontaneous Globe Rupture During Injection of Perfluoro-n-Octane (PFO) During Retinal Detachment Repair

The authors describe a case of spontaneous globe rupture during instillation of perfluoro-n-octane (PFO) during retinal surgery. A 71-year-old male with a macular-involving rhegmatogenous retinal detachment underwent pars plana vitrectomy. During instillation of PFO manually on a single-bore cannula by the assisting resident, spontaneous globe rupture occurred superotemporally in an area with no visible underlying structural abnormalities. Factors that led to this complication include the use of single-bore cannula, error in judgment of resistance during PFO injection, and inexperience. This is the first report of this complication without an identifiable structural abnormality predisposing patient to perforation.

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.

Internal limiting membrane flap technique in macular hole surgery.

Vitrectomy combined with internal limiting membrane (ILM) peeling is popular for the treatment of macular hole (MH). However, the improvements of MH closure rate and postoperative visual acuity are not satisfactory especially in large and refractory MHs. Currently, the ILM flap technique has gradually been applied for the treatment of MH and achieved high MH closure rate. The ILM flap technique has many variations, including the difference of the size, shape, number, and manner in which the flaps put on the MHs. The ILM flap technique also has some auxiliary means including perfluoro-n-octane (PFO), dye, autologous blood and adhesive viscoelastics. There is controversy about the effects between several technique variations of ILM flap, and it needs to be explored in the future.

MANAGEMENT OF GIANT RETINAL TEARS USING TRANSSCLERAL DIODE LASER RETINOPEXY AND SHORT-TERM POSTOPERATIVE TAMPONADE WITH PERFLUORO-N-OCTANE.

To determine the results of pars plana vitrectomy for giant retinal tear detachments using transscleral diode laser retinopexy and short-term postoperative tamponade with perfluoro-n-octane (PFnO). Twenty consecutive patients with fresh giant retinal tears were enrolled in a single-arm prospective study. One case was withdrawn for technical reasons. The remainder all underwent pars plana vitrectomy, PFnO injection, transscleral diode laser retinopexy to the edge of the giant retinal tear, and short-term postoperative heavy liquid tamponade. None of the cases had scleral buckling or lensectomy. Nineteen cases (18 male and 1 female) with a mean age of 41 years (range 10-69 years) were followed up for a period of 6 months. Postoperative tamponade with PFnO was maintained for a mean of 7.6 days (range 4-21 days), after which it was exchanged for sulfur hexafluoride (SF6), perfluoropropane (C3F8) gas, or balanced salt solution. Final reattachment rate was 100%, with 3 (15.7%) patients requiring additional surgery. Best-corrected visual acuity at final follow-up was 20/40 or better in 11 eyes (58%), between 20/60 and 20/200 in 7 (37%), and 20/400 in 1 (5%). In this series of acute giant retinal tears, transscleral diode laser retinopexy together with the use of PFnO for short-term postoperative tamponade achieved excellent anatomical and visual results.

Comparison of Residual Subfoveal Fluid by Intraoperative OCT After Macula-Involving RRD Repair Using Direct Drainage, Drainage Retinotomy, or Perfluoro-n-Octane.

This study evaluated the residual subfoveal fluid (SFF) immediately after rhegmatogenous retinal detachment (RRD) repair using intraoperative optical coherence tomography (iOCT). This retrospective cohort study assessed fovea-involving RRD repaired by pars plana vitrectomy (PPV) using different drainage techniques. iOCT images were acquired through the fovea at the start of the case prior to initiating vitrectomy and then again immediately prior to introduction of tamponade. Ten eyes (32.3%) received perfluoro-n-octane (PFO), 12 (38.7%) underwent a posterior drainage retinotomy, and nine (29.0%) had drainage through the retinal break. There was no significant difference in the mean SFF thickness between eyes in either group (P = .85). There was no significant association between SFF thickness on iOCT and functional or anatomic outcomes (P > .05). There is no difference in the amount of residual SFF as measured on iOCT during RRD repair with pars plana vitrectomy using either direct drainage, drainage retinotomy, or PFO. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:497-503.].

Perfluoro-n-octane-assisted autologous internal limiting membrane plug for refractory macular hole surgery.

To evaluate a surgical technique using a perfluoro-n-octane (PFO)-assisted autologous internal limiting membrane (ILM) plug for refractory macular holes (MHs). This study was a retrospective, consecutive, interventional case series. Patients with refractory MHs following PFO-assisted autologous ILM plugs were reviewed between October 1, 2017, and February 28, 2018. The anatomical results of MH preoperatively and postoperatively were evaluated by fundus examination and optical coherence tomography (OCT). The best-corrected visual acuities (BCVAs) before and after surgery were compared as the functional outcome. Six eyes of six consecutive patients with refractory MH were enrolled in this study. Successful MH closure and BCVA improvement after the surgeries were obtained in all eyes. There were four male and two female patients, and the mean age was 63.7 ± 11.1years. Intraoperatively, the average number of autologous ILM grafts we harvested was 2.2 ± 0.4. The mean follow-up was 6.0 ± 1.7months. The averaged BCVA before and after the surgery at the last visit improved from 20/356 to 20/153. The ILM graft tissue was still visible, as shown by OCT, in all 6 of 6 (100%) eyes during the follow-up period. This surgical technique using PFO-assisted autologous ILM plug may provide an option for the treatment of refractory MH.

Perfluorocarbon liquid-assisted intraocular foreign body removal.

We describe the benefits of perfluoro-N-octane (PFO), a perfluorocarbon liquid, in the removal of nonmagnetic intraocular foreign bodies (IOFBs) from the macula and posterior segment. Two consecutive cases of posterior segment IOFB were reviewed. An 18-year-old male presented to the emergency room after a motor vehicle accident with a zone 1 open globe injury and large glass IOFB in the left eye. A 53-year-old male presented to the emergency room with a history of a 3-week delayed presentation of a zone 1 open globe injury from a nail to the right eye. He was found to have a metallic IOFB. In both cases, PFO was used to slide the nonmagnetic IOFBs outside of the macula for safer retrieval. PFO was also able to protect the posterior pole from IOFB drops during early attempts at removal. PFO can be a useful surgical adjunct to pars plana vitrectomy in the removal of certain nonmagnetic IOFBs.

A Modified Perfluoro-n-octane-Assisted Autologous Internal Limiting Membrane Transplant for Failed Macular Hole Reintervention: A Case Series.

The authors describe a modified perfluoro-n-octane (PFO)-assisted autologous internal limiting membrane (ILM) transplantation technique for macular hole (MH) reintervention and present results from a series of 11 patients. The authors harvested a free ILM flap and transplanted it into the MH under a PFO bubble. The time at which PFO is injected, the extent of coverage of PFO, and the sequence of fluid-air exchange (FAE) are crucial to overcome previously described technical difficulties of relieving the flap from forceps, stabilizing the flap into the MH, and prevention of flap dislodgement during FAE. A successful U-shaped closure was observed in 10 of 11 cases (90.9%). One case (9.1%) showed flat open closure. The postoperative visual gain was statistically significant (P = .01). [Ophthalmic Surg Lasers Imaging Retina. 2017;48:416-420.].

In vitro experiment to elucidate the mechanism of the 'soft shell technique' for preventing subretinal migration of perfluoro-octane.

Perfluorocarbon liquid (PFCL) can migrate into subretinal space in detached and stiffened retina with open holes during vitreoretinal surgery. An innovative 'soft shell' technique was introduced to reduce the complication using hyaluronate (HA) to 'cover' the retinal hole. This study aims to study the effectiveness of this technique in vitro. Ex vivo porcine retina was mounted on a transwell insert. Beneath the retina was an aqueous solution. Two retinal holes were made using needle punctures. One of the two retinal holes was covered with HA. Perfluoro-n-octane (PFO) was added above the retina incrementally using a syringe pump. The height of PFO required to cause the migration of PFO through the retinal holes was measured. The 'pendant drop' method was carried out to measure the interfacial tensions between the PFO and aqueous, and between PFO and four different concentrations of HA solution. A statistically higher PFO level was required to cause the migration of PFO through the retinal hole with HA coating than without HA coating (Tobit regression with p<0.05). The use of HA was associated with 2.39-fold increase in hydrostatic pressure before the collapse of the PFO interface at the retinal holes. The interfacial tension between PFO and HA solution with concentrations of 0.05%, 0.25%, 0.5% and 1% were 54.2±0.6, 55.3±0.6, 59.5±1.5 and 68.3±1.3 mN/m, respectively (mean±SD). The interfacial tension between PFO and aqueous with 1% HA coating (68.3±1.3 mN/m) was significantly higher than that without (37.4±3.4 mN/m) (p<0.05). The interfacial tension between HA and PFO is higher than that between aqueous and PFO. This is a plausible physical explanation of how the 'soft shell' technique might work to prevent subretinal migration of PFCL.

Rapid detection of bacterial endotoxins in ophthalmic viscosurgical device materials by direct analysis in real time mass spectrometry

Bacterial endotoxins are lipopolysaccharides bound to the bacterial cell wall and released when bacteria rupture or disintegrate. Possible contamination of endotoxin in ophthalmic devices can cause a painful eye inflammation or result in toxic anterior segment syndrome after cataract surgery. Measurement of bacterial endotoxin in medical device materials is difficult since endotoxin binds with polymer matrix and some of the materials are very viscous and non-water soluble, where traditional enzyme-based Limulus amebocyte lysate (LAL) assay cannot be applied. Here we propose a rapid and high throughput ambient ionization mass spectrometric (MS) method using direct analysis in real time (DART) for the evaluation of endotoxin contamination in medical device materials. Large and structurally complex endotoxin instantaneously breaks down into low-mass characteristic fragment ions using DART and is detected by MS in both positive and negative ion modes. This method enables the identification and separation of endotoxin from medical materials with a detection limit of 0.03 ng mL−1 endotoxins in aqueous solution. Ophthalmic viscosurgical device materials including sodium hyaluronate (NaHA), non-water soluble perfluoro-n-octane (PFO) and silicone oil (SO) were spiked with different known concentrations of endotoxin and analyzed by DART MS, where the presence of endotoxin was successfully detected and featured small mass fragment ions were generated for NaHA, PFO and SO as well. Current findings showed the feasibility of measuring endotoxin contamination in medical device materials using DART-MS, which can lead to a one-step analysis of endotoxins in different matrices, avoiding any potential contamination during sample pre-treatment steps.

The Soft Shell Technique To Prevent Leakage of Perfluorocarbon Liquid Into The Subretinal Space

PurposePerfluorocarbon liquid (PFCL) can be used to unfold the retina during vitreoretinal surgery. The subretinal migration of PFCL is an undesirable complication of its use in cases with posterior retinal breaks particularly with associated proliferative vitreoretinopathy. The ‘soft shell’ technique, which is the use of hyaluronate (HA) to cover the break, has been described to prevent such migration. Our aim is to assess the scientific basis of this technique.MethodsA porcine retina model with two holes on a transwell was used to mimic the retinal breaks in vivo. HA solution was used to cover one of the holes. Perfluoro‐n‐octane (PFO) was added on top of the retina model incrementally using a syringe pump. The liquid level of PFO required to cause rupture of the PFO/aqueous interface with or without the HA coating at the two holes was measured. The interfacial tensions between the PFO against water and against HA solution with different aqueous concentrations were measured using pendant drop analysis.ResultsThe interfacial tension between PFO and aqueous with HA coating (68.3 ± 1.29 mN/m) is statistically significant higher than the PFO/aqueous interface without hyaluronate (37.4 ± 3.40 mN/m) (p &lt; 0.05). A higher PFCL level is required to cause the rupture of the PFO/aqueous interface at the hole with HA coating.ConclusionsA greater hydrostatic pressure is needed to rupture the PFO/aqueous interface in the presence of HA coating at the break. The increase may due to the increase in interfacial tension at the interface. This study provides the scientific explanation how the soft shell technique may work.