Utility of Automated Infrared Pupillometry in Assessing the Prolonged Course of Organophosphate Poisoning: A Case Report

Central and autonomic nervous system signs of organophosphate poisoning (OP), such as altered consciousness, noticeable lacrimation, and salivation, can be influenced by medications used in intensive care settings, such as atropine and pralidoxime methyl (PAM). Because of this, there are no established methods for assessing the duration of OP while receiving antidotal treatment. In the present case, we used the Neurological Pupil Index (NPi) to evaluate the duration of OP in an 82-year-old woman who attempted suicide by ingesting up to 100 mL of fenitrothion. Until hospitalization day (HD) 20, discontinuation of atropine led to the recurrence of altered consciousness, while its reinstatement resulted in improvement; this made it difficult to assess the prolongation of OP based on signs and symptoms. Until HD 20, the NPi remained at 0/0, and subsequently, it increased. Additionally, even after discontinuing atropine, consciousness, tearing, and salivation did not worsen, indicating recovery from OP. On HD 26, serum acetylcholinesterase (AChE) levels were elevated above the measurable level for the first time, following an increase in the NPi. In this case, assessing the persistence of OP based on signs was challenging because these signs improved with atropine and PAM treatment. The improvement in NPi levels coincided with an improvement in poisoning, suggesting that NPi is useful for evaluating the duration of OP. NPi is noninvasive and sensitive compared to AChE, which is used to gauge the persistence of OP and could be used to allow earlier cessation of medication and guide appropriate treatment durations.

Mitigation of pesticide-mediated ocular toxicity via nanotechnology-based contact lenses: a review

The xenobiotic stress exerted by pesticides leads to the deterioration of human and animal health including ocular health. Acute or prolonged exposure to these agricultural toxicants has been implicated in a number of pathological conditions of the eye such as irritation, epiphora or hyper-lacrimation, abrasions on the ocular surface, and decreased visual acuity. The issue is compounded by the fact that tissues of the eye absorb pesticides faster than other organs of the body and are more susceptible to damage as well. However, there is a lacuna in our knowledge regarding the ways by which pesticide exposure-mediated ocular insult might be counteracted. Topical instillation of drugs known to combat the pesticide induced toxicity has been explored to mitigate the detrimental impact of pesticide exposure. However, topical eye drop solutions exhibit very low bioavailability and limited drug residence duration in the tear film decreasing their efficacy. Contact lenses have been explored in this respect to increase bioavailability of ocular drugs, while nanoparticles have lately been utilized to increase drug bioavailability and increase drug residence duration in different tissues. The current review focuses on drug delivery and futuristic aspects of corneal protection from ocular toxicity using contact lenses.

Effect of supersaturated oxygen emulsion treatment on chloropicrin-induced chemical injury in ex vivo rabbit cornea

With a possibility for the use of chemical weapons in battlefield or in terrorist activities, effective therapies against the devastating ocular injuries, from their exposure, are needed. Oxygen plays a vital role in ocular tissue preservation and wound repair. We tested the efficacy of supersaturated oxygen emulsion (SSOE) in reducing ex vivo corneal and keratocyte injury from chloropicrin (CP). CP, currently used as a pesticide, is a chemical threat agent like the vesicating mustard agents and causes severe corneal injury. Since our previous study in human corneal epithelial cells showed the treatment potential of SSOE (55 %), we further tested its efficacy in an ex vivo CP-induced rabbit corneal injury model. Corneas were exposed to CP (700 nmol) for 2 h, washed and cultured with or without SSOE for 24 h or 96 h. At 96 h post CP exposure, SSOE treatment presented a healing tendency of the corneal epithelial layer, and abrogated the CP-induced epithelial apoptotic cell death. SSOE treatment also reduced the CP induced DNA damage (H2A.X phosphorylation) and inflammatory markers (e.g. MMP9, IL-21, MIP-1β, TNFα). Further examination of the treatment efficacy of SSOE alone or in combination with other therapies in in vivo cornea injury models for CP and vesicants, is warranted.

A national toxicology program systematic review of the evidence for long-term effects after acute exposure to sarin nerve agent

Sarin is a highly toxic nerve agent that was developed for chemical warfare during World War II and is used in present conflicts. Immediate effects of acute sarin exposure are established; however, whether effects persist after initial signs have subsided is debated. The National Toxicology Program (NTP) conducted a systematic review to evaluate the evidence for long-term neurological effects following acute (<24 hour) exposure to sarin. The literature search and screening process identified 32 data sets within the 34 human studies and 47 data sets within the 51 animal studies (from 6837 potentially relevant references) that met the objective and the inclusion criteria. Four main health effect categories of neurological response were identified as having sufficient data to reach hazard conclusions: (1) cholinesterase levels; (2) visual and ocular effects; (3) effects on learning, memory, and intelligence; and (4) morphology and histopathology in nervous system tissues. NTP concluded that acute sarin exposure is known to be a neurological hazard to humans in the period following exposure up to 7 days and suspected to be a hazard week to years after exposure, given a lower level of evidence in later time periods. Effects included reduced cholinesterase, visual and ocular effects, impaired learning and memory, and altered nervous system morphology. Further mechanistic, targeted animal studies, translational research, and rapid research responses after human exposures may reduce uncertainties on long-term consequences of sarin.

Broad Spectrum Treatment for Ocular Insult Induced by Organophosphate Chemical Warfare Agents

Warfare organophosphates nerve agents constitute one of the prime threats to mankind on the battlefield and in the scenario of civilian terror. Exposure to organophosphate (OP) nerve agents dose-dependently result in incapacitation. They affect multiple organs, but the eye is one of the first and most frequently affected. Ocular OP insult may result in long-term miosis, impaired visual function, and ocular pain thus inducing functional incapacitation. The currently recommended military medical doctrine of using 1% atropine eye drops is far from being the optimal treatment. Although effective in reducing ocular pain and the miotic response, this treatment induces long-term mydriasis and cycloplegia promoting photophobia and restricted accommodation, which may result in further impairment in visual function. An optimal treatment must ameliorate the long-term ocular insult enabling rapid return of normal visual function, while avoiding the induction of mydriasis and cycloplegia side effects, which could possibly worsen the visual performance. Optimal treatment should also keep effects of misuse to a minimum. Work done in recent years examined treatments with various anticholinergic drugs alone or used in combination with oxime treatments and may offer improved efficacy in ameliorating the ocular insult. This review is a summary of the applied research in animals and will discuss clinical implications and possible alterations in treatment protocols following OP exposure. Taken together the data points toward the use of topical low concentrations of potent anticholinergic ophthalmic drops such as atropine or homatropine, which rapidly ameliorate the long-term OP-induced ocular insult.

Ocular surface histopathological insult following sarin and VX exposure and potential treatments in the rat model

Eye exposure to organophosphate (OP) chemical warfare irreversible acetylcholinesterase inhibitors, results in long-term miosis and impaired visual function. In contrast to the well-documented miotic and ciliary muscle spasm observed following chemical warfare, OP ocular exposure, little is known regarding the ocular surface histopathological insult. The aim of the present study was to determine the degree of the ocular surface insult following sarin or VX ocular exposure and to evaluate potential anti-cholinergic treatments in counteracting this insult. Rats that were whole body exposed to various sarin concentrations (0.049-43 μg/L; 5 min exposure), showed a dose-dependent miotic response and light reflex impairment. Following whole body sarin exposure, a dose dependent ocular surface histopathological insult was developed. A week following exposure to a low concentration of 0.05 μg/L, conjunctival pathology was observed, while corneal insult was noticed only following exposure to a concentration of 0.5 μg/L and above. Both tissues presented poorer outcomes when exposed to higher sarin concentrations. In contrast, eyes topically exposed to 1 μg sarin demonstrated no ocular insult a week following exposure. On the contrary, topical exposure to 1 μg VX resulted in a significant corneal insult. Anticholinergic treatments such as 0.1% atropine or 2% homatropine, given shortly following VX exposure, counteracted this insult. The results of this study show that not only do anti-cholinergic treatments counteract the miotic response, but also prevent the histopathological insult observed when given shortly following OP exposure.