Visualization and Identification of Silicone Oil Emulsification Using Dynamic Infrared Confocal Scanning Laser Ophthalmoscopy.

Introduction: Silicone oil (SO) is a crucial agent used as an intraocular tamponade in the treatment of complex vitreoretinal diseases. Despite its effectiveness, SO is prone to emulsification, which can lead to significant and sometimes irreversible complications in both the anterior and posterior segments of the eye. The detection and monitoring of SO emulsification are therefore of paramount importance. Traditional imaging modalities have limitations in visualizing SO, leading to the exploration of more advanced imaging techniques. This study introduces the application of dynamic infrared confocal scanning laser ophthalmoscopy (IRcSLO) for this purpose and evaluates its effectiveness. Case Presentation: We report on 2 patients who underwent pars plana vitrectomy with subsequent SO injection for the management of retinal detachment. Postsurgery, both patients were imaged using the Heidelberg Retina Tomography Spectralis IRcSLO. The focus was on the visualization of the SO status, including the presence and distribution of emulsified SO droplets. The IRcSLO imaging technique demonstrated its capability to effectively visualize emulsified SO droplets. Interestingly, this was also true for cases where the SO had been removed. The emulsified droplets were observed as micron-sized, spherical entities with a nonuniform distribution throughout the vitreous cavity. Conclusion: Dynamic IRcSLO has proven to be an effective imaging modality for visualizing the emulsification of SO, offering a novel perspective into the characterization of SO droplets. It facilitates the analysis of droplet count, motility, and precise localization within the vitreous cavity. The findings from the case presentations underscore the variability of SO emulsification patterns and the sensitivity of IRcSLO in detecting even minuscule emulsified droplets. This imaging technique has significant potential for future research, particularly in understanding the timing of emulsification, the factors contributing to it, and the development of possible preventive strategies. Additionally, it allows for a more in-depth analysis of the behavior of emulsified SO droplets across different SO viscosities, which could be instrumental in optimizing patient outcomes.

Safety, biocompatibility, and potential functionality of a new accommodative intraocular lens: An experimental study in rabbits.

This study aims to evaluate the safety, biocompatibility, and functionality of a new accommodative intraocular lens (IOL) (LUZ, patent PCT/ES2016/070,813) after implantation in rabbit eyes. LUZ (Study) and EyeCee® plus a capsular ring (Control) were implanted in rabbits (n = 8 each) after phacoemulsification. Intraoperative follow-up, long-term clinical follow-up, and functional IOL studies were carried out periodically for up to 180 days. A macroscopic examination of the eyeballs to reveal abnormalities and determine the implant centering and a microscopic examination to semi-quantify cell and tissue response were performed. Statistical analysis of the collected data was finally achieved. During follow-up, no significant changes in the general condition nor the clinical evaluation were observed between both groups. However, Study IOL remained centered throughout the study and did not present severe complications as observed in the Control group. Functional studies did not reveal significant differences between both materials. Study showed better centering, fewer adhesions, and maintenance of an opening capsular bag compared to the Control. Local biological effects caused by Study implantation are minimal and comparable to the Control. Therefore, LUZ showed no clinical signs or histological response of adverse reaction to the implanted material, according to UNE-EN ISO 11979-5 and 10993-6. Functionality must be confirmed in another animal species with greater lens accommodation capacity than the rabbit. LUZ keeps the capsular bag open, favoring its centering and avoiding fibrosis and adherence to the bag; this allows potential accommodation of this IOL and theoretically enables the patient to focus dynamically.

Ala®sil chemical characterization and toxicity evaluation: an example of the need for the Medical Device Regulation 2017/745.

Introduction: Ala®sil infusion was on the market for clinical use under the Medical Devices Directive (MDD) 93/42/EEC as an irrigating solution based on polydimethylsiloxane (PDMS). The product was withdrawn in 2016, and to the best of our knowledge, it did not cause any health damage. Methods: A bibliographic review and experimental analysis were conducted to evaluate whether this CE-marked product could have been used in patients under the current Medical Device Regulation (MDR) 2017/745. Analytical results from gas chromatography-mass spectrometry (GC-MS) and matrixassisted laser desorption ionization (MALDI) were performed. Citotoxicity studies were also carried out. Results: Only one study related to Ala®sil clinical use was found, describing a pilot series of five patients. The authors rated the product as not helpful in three out of the five cases for internal searching of retinal breaks and in four out of the five cases for drainage of subretinal fluid. No other scientific papers or documentation was found regarding Ala®sil's safety. Nevertheless, the product was introduced in the market after achieving the CE marking. GC-MS and MALDI showed that the polymer has a low molecular weight of 1,000 g/mol. Several linear and cyclic low-molecular-weight components (LMWCs) were identified as impurities ranging from L3 to D8, with a molecular weight below 600 g/mol. The Ala®sil sample was found to be cytotoxic after 24 h of cell culture but non-cytotoxic after 72 h, probably due to the cellular regeneration capacity of an immortalized cell line. Tissular cytotoxicity revealed an increased apoptosis rate but without morphological modifications. Discussion: Although Ala®sil cannot be classified as cytotoxic, this substance appears to increase retinal cell death processes. This study supports the notion that the MDDwas not functioning adequately to ensure the safety of medical devices. However, the current MDR 2017/745 imposes stricter standards to prevent the commercialization of medical devices without high-quality preclinical and clinical information, as well as precise clinical verification for their use, information not available for Ala®sil infusion.

Acute intraocular toxicity caused by perfluorocarbon liquids: safety control systems of medical devices.

BACKGROUND: Acute retinal toxicity has been demonstrated to be associated with the intraoperative use of perfluorocarbon liquids (PFCLs), especially perfluorooctane (PFO). Recently, several cases of PFO-associated blindness have been reported in Spain, Holland, France, Italy, the Middle East, and South America. METHODS: As a result, a new ISO guideline (ISO 16672:2020) was drafted, discussed, approved, and released in 2019. This recent ISO16672:2020 guideline recommends performing direct cytotoxicity tests as an option along with chemical analysis to measure PFCL quality (purity and safety). RESULTS: In this review paper, it has been emphasized why an appropriate biological test, specifically direct exposure of PFCL to live cells, for measuring cytotoxicity must be performed with each PFCL batch along with chemical analysis. CONCLUSIONS: The paper intends to compile all available information to discuss possible approaches for avoiding adverse clinical cases in future.

Complications associated with the use of silicone oil in vitreoretinal surgery: A systemic review and meta-analysis.

Silicone oil (SO) still represents the main choice for long-term intraocular tamponade in complicated vitreoretinal surgery. This review compared the complications associated with the use of SO and other vitreous substitutes after pars plana vitrectomy in patients with different underlying diseases. Meta-analysis was conducted in accordance with PRISMA guidelines. We retrieved randomized clinical trials (RCTs), retrospective case-control and cohort studies evaluating the risk of using SO, published between 1994 and 2020, conducting a computer-based search of the following databases: PubMed, Web of Science, Scopus and Embase. Primary outcome was the rate of complications such as intraocular hypertension, retinal re-detachment, unexpected vision loss or hypotony. Secondary outcome was to compare the rate of adverse events of different SO viscosities, especially emulsification. Forty-three articles were included. There were significant differences in intraocular hypertension (p = 0.0002, OR = 1.66; 95% CI = 1.27-2.18) and the rate of retinal re-detachment (p < 0.0009, OR = 0.65; 95% CI = 0.50-0.64) between SO and other agents, including placebo. However, there were no differences in other complication rates. Silicone oil (SO)-emulsification rate was non-significantly higher in low than high SO viscosity, and results from other complications were comparable in both groups. The high quality of most of the studies included in this study is noteworthy, which provides some certainty to the conclusions. Among them is the high variability of the SO residence time. The fact that ocular hypertension and not hypotension is related to SO use. A clear relationship is not found for the so-called unexplained vision loss, which affects a significant percentage of eyes. Re-detachment cases are less if SO is used and that surprisingly there does not seem to be a relationship in the percentage of emulsification between the low- and high-viscosity silicones. All these data warrant more standardized prospective studies.

Ex-Vivo Method to Quantifiably Evaluate the Staining Effectiveness of Anterior Lens Capsule Dyes.

Purpose: High frequency of cataracts and the requirements of new European Union regulations for medical devices require the availability of preclinical models to adequately evaluate anterior lens capsule dyes before their use in patients. Herein, we describe an ex vivo method to quantifiably evaluate the macroscopic and microscopic staining effectiveness of anterior lens capsule dyes using porcine eyes. Methods: Commercially available trypan blue-based products or physiological saline solution (negative control) was injected into porcine eyes. Anterior pole and lens (after extraction) were macroscopically photographed, and the images were quantitatively analyzed. Lenses were histologically processed, and the staining intensity microscopically was semiquantified. Results: Macroscopic evaluation of the anterior pole revealed bluish staining of the anterior capsule; however, this coloring cannot be macroscopically discerned after lens extraction. Quantitative image analyses showed significant (P < 0.01) staining of the lens capsule compared to the negative control, but not significant (P > 0.05) between the products tested. Quantitative analysis of dying on lens images could not be performed. Microscopic semiquantification of the capsule staining intensity allows us to appreciate differences between products. Conclusions: The described method is a quick and useful tool for macroscopic evaluation by surgeons to choose an anterior capsule staining for use during everyday surgeries, and a more specific microscopic evaluation also allows us to determine the effectiveness and usefulness of these products. Translational Relevance: This method satisfies preclinical effectiveness evaluations required by European Union regulations and complements the safety and toxicity evaluations that new products must guarantee before they enter the market and are used in clinical practice.

Intraocular toxicity caused by MEROCTANE perfluorocarbon liquid.

Serious intraocular toxicity cases have been reported worldwide after the use of different perfluorocarbon liquids. The current study reports for the first-time the clinical pictures of cases of acute intraocular toxicity caused by MEROCTANE, a perfluoro-octane commercialized by a Turkish company and distributed in many countries. A series of 18 cases from Chile and Spain was retrospectively analysed. To evaluate the impurity profile, a suspicious MEROCTANE sample (lot OCT.01.2013) was analysed by gas chromatography mass spectrometry and compared with a non-suspicious sample of the same commercial perfluoro-octane (lot OCT 722011). Cytotoxicity was tested following a direct-contact method, taking into consideration the high volatility and hydrophobicity of perfluoro-octane and following the ISO 10993 guideline. Cytotoxicity test showed clear cytotoxic effects of the analysed batch (less than 9% of cell viability). Moreover, chemical analysis demonstrated the presence of many contaminants, some highly toxic (acids and alcohols). Perfluorocarbon liquids are useful tools for intraocular surgery but companies and Agencies of Medical Devices must implement measures that guarantee the safety of these products based on both chemical and cytotoxicity analysis for every batch. Medical staff should be encouraged to report any suspected case to their respective National Agencies.

Chemical compounds causing severe acute toxicity in heavy liquids used for intraocular surgery.

Perfluorocarbon liquids (PFCLs) have been considered safe for intraocular manipulation of the retina, but since 2013 many cases of acute eye toxicity cousing blindness have been reported in various countries when using various commercial PFCLs. All these PFCLs were CE marked (Conformité Européenne), which meant they had been subjected to evaluation complying with the International Organization for Standardization (ISO) guidelines. These dramatic events raised questions about the safety of PFCLs and the validity of some cytotoxicity tests performed under ISO guidelines. Samples from toxic batches were analyzed by gas chromatography-mass spectrometry combined with Raman and infrared spectrometry. Perfluorooctanoic acid, dodecafluoro-1-heptanol, ethylbenzene and tributyltin bromide were identified and evaluated by a direct contact cytotoxicity test using ARPE-19 cell line, patented by our group (EP 3467118 A1). Perfluorooctanoic acid at a concentration of >0.06 mM and tributyltin bromide at a concentration of ≥0.016 mM were shown to be toxic, whereas the concentration found in the toxic samples reached 0.48 mM, and 0.111 mM, respectively. These finding emphasized the idea that determination of partially fluorinated compounds are not enough to guarantee the safety of these medical devices.

Production of molecular weight fractionated hemicelluloses hydrolyzates from spent coffee grounds combining hydrothermal extraction and a multistep ultrafiltration/diafiltration.

Spent coffee grounds are a huge residual stream from instant coffee makers. The production of spent coffee oil and molecular weight fractionated hemicellulose hydrolysates via supercritical CO2 and a hydrothermal treatment followed by concentration, separation, and purification through cascade ultrafiltration/diafiltration (30-10-5 kDa) was studied. Hemicelluloses extraction yield reached 3.49 g/100 g of dry defatted spent coffee after 40 min at 160 °C. The ultrafiltration system allowed concentrating up to 5-fold certain groups of hemicellulose, being most of them retained in the first membrane. Hemicellulose concentration and molecular weight of the feed exerted a great influence on the mass transfer through the membrane due to the formation of aggregates. However, purification through diafiltration allowed both to decrease by-products retentions from 45.6% to 8.7%, increasing the molecular weight of each fraction. Six hemicellulose products were obtained with purities between 83.7 and 97.8 wt% and weight-average molecular weights between 1641 and 49,733 Da.

Acute retinal toxicity associated with a mixture of perfluorooctane and perfluorohexyloctane: failure of another indirect cytotoxicity analysis.

AIMS: To report new information related to acute retinal toxicity of Bio Octane Plus, a mixture of 90% perfluorooctane (PFO) and 10% perfluorohexyloctane. METHODS: This retrospective, descriptive case series reports the occurrence of acute retinal toxicity after vitreoretinal surgery in which Bio Octane Plus (batch number 1605148) was used as an endotamponade. Cytotoxicity biocompatibility tests and chemical analyses by Fourier-transformed infrared (FTIR) spectroscopy and gas chromatography-mass spectrometry (GC-MS) of the presumed toxic product were performed. RESULTS: Four patients presented with acute severe visual loss after uneventful ocular surgery assisted by Bio Octane Plus (batch number 1605148) as endotamponade. Patients experienced extensive retinal vascular occlusion leading to retinal and optic nerve atrophy. The viability of ARPE-19 cells directly exposed to the suspect batch for 30 min was 0%. The agarose overlay method used by the manufacturer according to European Union regulations and International Organization for Standardization (ISO) International Standards failed to detect toxicity. FTIR spectroscopy showed small differences between the non-toxic and toxic batches. GC-MS analysis showed the presence of bromotributyl stannane (whose toxicity was demonstrated in the dose-response curve) only in the toxic batch of Bio Octane Plus. CONCLUSION: This is the third report of retinotoxicity due to PFO in 4 years. The clinical profiles may be missed as they resemble other postsurgical complications; therefore, more cases worldwide could have gone unreported. Protocols to determine cytotoxicity of intraocular medical devices and approved by the ISO International Standards based on indirect methods have failed and should be revised to ensure safety.

Low-alcohol Beers: Flavor Compounds, Defects, and Improvement Strategies.

Beer consumers are accustomed to a product that offers a pleasant and well-defined taste. However, in alcohol-free and alcohol-reduced beers these characteristics are totally different from those in regular beer. Therefore, it is important to evaluate and determine the different flavor compounds that affect organoleptic characteristics to obtain a product that does not contain off-flavors, or taste of grass or wort. The taste defects in alcohol-free beer are mainly attributed to loss of aromatic esters, insufficient aldehydes, reduction or loss of different alcohols, and an indeterminate change in any of its compounds during the dealcoholization process. The dealcoholization processes that are commonly used to reduce the alcohol content in beer are shown, as well as the negative consequences of these processes to beer flavor. Possible strategies to circumvent such negative consequences are suggested.

Simulation and flavor compound analysis of dealcoholized beer via one-step vacuum distillation.

The coupled operation of vacuum distillation process to produce alcohol free beer at laboratory scale and Aspen HYSYS simulation software was studied to define the chemical changes during the dealcoholization process in the aroma profiles of 2 different lager beers. At the lab-scale process, 2 different parameters were chosen to dealcoholize beer samples, 102mbar at 50°C and 200mbar at 67°C. Samples taken at different steps of the process were analyzed by HS-SPME-GC-MS focusing on the concentration of 7 flavor compounds, 5 alcohols and 2 esters. For simulation process, the EoS parameters of the Wilson-2 property package were adjusted to the experimental data and one more pressure was tested (60mbar). Simulation methods represent a viable alternative to predict results of the volatile compound composition of a final dealcoholized beer.

New trends in beer flavour compound analysis.

As the beer market is steadily expanding, it is important for the brewing industry to offer consumers a product with the best organoleptic characteristics, flavour being one of the key characteristics of beer. New trends in instrumental methods of beer flavour analysis are described. In addition to successfully applied methods in beer analysis such as chromatography, spectroscopy, nuclear magnetic resonance, mass spectrometry or electronic nose and tongue techniques, among others, sample extraction and preparation such as derivatization or microextraction methods are also reviewed.

Mass spectrometry-based metabolomics approach to determine differential metabolites between regular and non-alcohol beers.

Non-alcohol beers show taste deficiencies in relation to regular (alcohol) beers as shown by consumer evaluation. In this study, multivariate statistical analysis of data obtained by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) measurements was applied to determining differential metabolites between two regular (R1 and R2) and their related low- and non-alcohol beers (F1 and F2, respectively) from a Spanish manufacturer, as well as between F1 and F2 and two non-alcohol beers (F3 and F4) from a non-Spanish producer. Principal component analysis (PCA) of data from UPLC-MS measurements with electrospray ionization in negative mode was able to separate the six beers. Sugar content was 6-fold and 2-fold higher in F2 and F1 than in R2 and R1, respectively. Isoxanthohumol and hop acid contents decreased in F2 as compared with R2 but kept in F1 similar to R1. Results are discussed in relation to valued taste characteristics of each beer type.