High-Frequency Application of Cationic Agents Containing Lubricant Eye Drops Causes Cumulative Corneal Toxicity in an Ex Vivo Eye Irritation Test Model

An Assessment of the Ocular Toxicity of Two Major Sources of Environmental Exposure

The effect of airborne exposure on the eye surface is an area in need of exploration, particularly in light of the increasing number of incidents occurring in both civilian and military settings. In this study, in silico methods based on a platform comprising a portfolio of software applications and a technology ecosystem are used to test potential surface ocular toxicity in data presented from Iraqi burn pits and the East Palestine, Ohio, train derailment. The purpose of this analysis is to gain a better understanding of the long-term impact of such an exposure to the ocular surface and the manifestation of surface irritation, including dry eye disease. In silico methods were used to determine ocular irritation to chemical compounds. A list of such chemicals was introduced from a number of publicly available sources for burn pits and train derailment. The results demonstrated high ocular irritation scores for some chemicals present in these exposure events. Such an analysis is designed to provide guidance related to the needed ophthalmologic care and follow-up in individuals who have been in proximity to burn pits or the train derailment and those who will experience future toxic exposure.

Impact of Latanoprost Antiglaucoma Eyedrops and Their Excipients on Toxicity and Healing Characteristics in the Ex Vivo Eye Irritation Test System

INTRODUCTION

Corneal epithelial toxicity and delayed healing process have already been attributed to preservatives or some excipients. We study the effects of galenic components in antiglaucoma drugs such as benzalkonium chloride (BAC) or surfactants like macrogolglycerol hydroxystearate 40 (MGHS 40) on corneal toxicity in an ex vivo system mimicking chronic use.

METHODS

Latanoprost-containing eyedrops are available with and without preservatives on the market. Unpreserved, they are available in different formulations with various excipients like MGHS at different concentrations (0%, 2.5%, and 5%). We studied these in the ex vivo bioreactor (EVEIT) on initially injured rabbit corneas. The drugs were applied six times daily for observation periods of 3 or 5 days. BAC, 5% MGHS 40 solution, and 0.18% hyaluronic acid served as controls. Macroscopic photographic, biochemical methods and corneal integrity quantification were used for evaluation. Toxicity was assessed by measuring wound healing and corneal fluorescein sodium permeability and was confirmed by histology studies.

RESULTS

The BAC-preserved formulation resulted in high corneal toxicity, which was expected. Interestingly, the preservative-free (PF) formulation containing 5% MGHS 40, carbomer, macrogol 4000, and sorbitol showed the highest corneal toxicity, followed by the control formulation with equal MGHS 40 concentration, which presented significantly less damage. No toxicity was shown by eyedrops containing 2.5% MGHS 40 or salts only.

CONCLUSION

Our study demonstrates a significant corneal toxicity of certain formulations of PF antiglaucoma ophthalmic drugs containing 5% MGHS 40 with other excipients compared to other formulations with lower MGHS 40 concentrations (2.5% or 0%), or even compared to the solution containing 5% MGHS alone. This suggests a concentration-dependent toxicity of MGHS 40, especially in interaction with other excipients, which may increase its epithelial toxicity, and that has to be considered in clinical glaucoma therapy. Further single-component formulation trials are needed to support this interpretation.

Quaternary ammonium compounds in hypersensitivity reactions

Quaternary ammonium compounds (QAC) are commonly used disinfectants, antiseptics, preservatives, and detergents due to their antibacterial property and represent the first used biocides before phenolic or nitrogen products. Their common structure consists of one or more quaternary ammonium bound with four lateral substituents. Their amphiphilic structure allows them to intercalate into microorganism surfaces which induces an unstable and porous membrane that explains their antimicrobial activity towards bacteria, fungi, and viruses. QAC are thus found in many areas, such as household products, medicines, hygiene products, cosmetics, agriculture, or industrial products but are also used in medical practice as disinfectants and antiseptics and in health care facilities where they are used for cleaning floors and walls. QAC exposure has already been involved in occupational asthma in healthcare workers or professional cleaners by many authors. They also have been suggested to play a role in contact dermatitis (CD) and urticaria in workers using cosmetics such as hairdressers or healthcare workers, inciting reglementary agencies to make recommendations regarding those products. However, distinguishing the irritant or sensitizing properties of chemicals is complex and as a result, the sensitizing property of QAC is still controverted. Moreover, the precise mechanisms underlying the possible sensitization effect are still under investigation, and to date, only a few studies have documented an immunological mechanism. Besides, QAC have been suggested to be responsible for neuromuscular blocking agents (NMBA) sensitization by cross-reactivity. This hypothesis is supported by a higher prevalence of quaternary ammonium (QA)-specific IgE in the professionally exposed populations, such as hairdressers, cleaners, or healthcare workers, suggesting that the sensitization happens with structurally similar compounds present in the environment. This review summarizes the newest knowledge about QAC and their role in hypersensitivities. After describing the different QAC, their structure and use, the most relevant studies about the effects of QAC on the immune system will be reviewed and discussed.

Management Strategies for Evaporative Dry Eye Disease and Future Perspective

Dry eye disease (DED) is a common disorder that remains challenging from a clinical perspective. Unstable or deficient tear film is a major factor contributing to DED and the inability to resolve the loss of tear film homeostasis that accompanies DED can result in a vicious circle of inflammation and treatment-refractory disease. Recently recognized as a multifactorial disease, the main etiological subtypes of DED are aqueous-deficient and evaporative which exist on a continuum, although evaporative dry eye (EDE) is the more frequent classification. Although attaining greater recognition in recent years, there is currently no consensus and no clear recommendation on how to manage EDE. Clarity on the early diagnosis and treatment of EDE may facilitate the avoidance of progression to chronic inflammation, permanent damage to the ocular surface, and treatment-refractory disease. The purpose of this review was to identify current best practice for management of EDE in order to help clinicians in providing accurate diagnosis and optimized treatment. We summarize recent literature considering the role of the lipid layer on tear film stability, the importance of its composition and of its dynamic behavior, and the link between its malfunction and the insurgence and maintenance of tear film-related diseases. We have provided an assessment of the best management of lipid-deficient EDE based upon an understanding of disease pathophysiology, while indicating the flow of current treatments and possible future evolution of treatment approaches. Lipid containing eye drops may be considered as a step closer to natural tears from artificial aqueous tears because they more closely mimic the aqueous and lipid layers and may be used in combination with other management approaches. As a next step, we recommend working with a wider expert group to develop full guidelines to enable patient-centered management of EDE. Key pointsDry eye is a multifactorial disease of variable presentation with the tendency to become a chronic disease for which it is essential to identify and treat the main pathogenic mechanisms involved and tailor the treatment to the individual patient.Early intervention is needed to prevent the vicious cycle of DED and may require a multi-faceted management approach.EDE is not just a problem of MGD but can be the result of anything affecting blinking, mucin spreading, aqueous layer volume and content.Lipid-containing eye drops may provide significant relief of symptoms by improving the lipid layer and its spreading ability and, as such, are an appropriate component of the overall management of lipid-deficient EDE; natural lipid-containing eye drops should be the preferred treatment.

Defining corneal chemical burns: A novel exact and adjustable ocular model

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Novel method induces highly reproducible chemical injuries in an ex vivo cornea model.

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Initial corneal surface humidity is an important parameter for consistent injury.

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The application frequency of the corrosive has a major impact on the extent of injury.

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This automated method can provide a consistent baseline for further investigations.

Introduction

Live-animal-free ocular toxicity models and tests are a necessity in multiple branches of medicine, industry and science. Corneal models with adjustable ranges of injury severities do not exist. In this work, a novel and precise and dose - response method to induce and observe ex vivo corneal chemical burns has been established.

Methods

The EVEIT (Ex Vivo Eye Irritation Test) is based on an ex vivo corneal organ model for rabbit corneas from food industry. Further, a highly precise three – axis workstation has been employed to apply liquid corrosive, sodium hydroxide (NaOH), droplets in a nanolitre (nL) range onto the corneal surface. Optical Coherence Tomography (OCT) has been used to observe and quantify the elicited changes in the corneal layers.

Results

The speed and intervals of single nanodroplet application played a crucial role in the extent of the corneal changes. Similar total volumes applied at low frequencies elicited deep and extensive changes in the corneal layers whereas high application frequencies elicited comparatively superficial changes. Increasing NaOH concentrations effected measurably increasing corneal changes. Increasing the volume of applied NaOH also showed an increase in corneal changes.

Conclusions

OCT imaging proved to be effective in observing, documenting and quantifying the changes in the corneal layers. The ex vivo model, in conjunction with the novel application method was able to induce and display distinctive and consistent correlations between NaOH volume, concentration and elicited corneal changes. This ex vivo ocular chemical burn model provides a consistent in vitro basis for pharmaceutical and toxicological experiments and investigations into corneal chemical burn mechanisms and treatment.

Antiseptic drugs and disinfectants with special scrutiny of COVID-19 pandemic related side effects

This review covers publications during the period of January 2020 to December 2020 on adverse reactions to antiseptic drugs and disinfectants. Specific agents discussed are alcohols (ethanol, isopropanol), aldehydes (formaldehyde), guanidines (chlorhexidine, polyhexamethylene guanidine, and polyhexamethylene biguanidine), benzalkonium compounds, triclocarban, povidone-iodine, and sodium hypochlorite. No new data were identified for glutaraldehyde, cetrimide, ethylene oxide, tosylchloramide, triclosan, iodine, and phenolic compounds. The use of antiseptic drugs and disinfectants has been considerably increased during 2020 in a variety of medical and occupational settings, in commerce and gastronomy, as well as in the household, due to their antiviral properties against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) during the Coronavirus Disease 2019 (COVID-19) pandemic. Exposure was additionally increased by widespread misinformation on social media for non-evidence based disinfectant use, even including ingestion or injection, as well as by questionable practices such as environmental spraying or disinfectant gates. Irritant effects on the respiratory system, skin and eyes were the most common adverse reaction, while the widespread and sometimes excessive use led to increased reports of poisonings, as well as cases of disinfectant adulteration including dilution into ineffective concentrations or addition of toxic agents such as methanol.