Nerve agents ocular toxicity

Exposure to acutely toxic concentrations of nerve agents can result in excessive bronchial, salivary, ocular and intestinal secretions, sweating, miosis, bronchospasm, intestinal hypermotility, bradycardia, muscle fasciculations, twitching, weakness, paralysis, loss of consciousness, convulsions, depression of the central respiratory drive, and death (Grob and Harvey, 1953 Grob, 1956 Marrs, 2007 Sidell, 1997 Yanagisawa et al, 2006 many others). Minimal effects observed at low vapor concentrations... 

Toxic effects occur within seconds to 5 min of nerve agent vapor or aerosol inhalation. The muscarinic effects include ocular (miosis, conjunctival congestion, ciliary spasm), nasal discharge, respiratory (bronchoconstriction and increased bronchial secretion), gastrointestinal (anorexia, vomiting, abdominal cramps, and diarrhea), sweating, salivation, and cardiovascular (bradycardia and hypotension) effects. The nicotinic effects include muscular fa-sciculation and paralysis. CNS effects can include ataxia, confusion, loss of reflexes, slurred speech, coma, and paralysis. 

Agent GA (tabun) is an organophosphate ChE inhibitor similar to other nerve agents in mode of action and toxic effects, and it is toxic by all possible exposure routes ingestion, inhalation, and ocular and percutaneous absorption (DA 1974). By the inhalation exposure route, GA is only half as toxic as GB however, at low concentrations it has a greater effect on the eyes (DA 1974). The acute toxicity of GA and other nerve agents has been reviewed in several earlier reports (Carnes and Watson 1989 Dacre 1984 Munro et al. 1994 Sidell 1992 ... 

The authors added that retinal toxicity of the local anesthetic agent did not affect the visual outcome in this patient. Scleral perforation is a well-known complication of eye blocks for ophthalmic surgery. The incidence with retrobulbar techniques is 0.075% and with peribulbar blocks 0.0002%. When recognized, ocular perforation usually requires a vitreoretinal procedure and is associated with a poor visual outcome. Risk factors include an anxious or oversedated patient, long sharp needles, superior injection, incorrect angle of needle insertion, and myopic eyes. If the intraocular pressure is increased, paracentesis may acutely reduce it, preventing retinal and optic nerve ischemia and possible permanent visual loss. 

CO-beneldopa benserazide levodopa. cocaine (ban, usan] (cocaine hydrochloride (jan, usan)) is an ester of benzoic acid and methylecgonine and the principal alkaloid of Erythroxylum coca and other Erythroxylum spp. (Erythroxylaceae). It is a LOCAL ANAESTHETIC (used topically because of toxicity), and has pronounced indirect-acting SYMPATHOMIMETIC actions by virtue of being an UPTAKE INHIBITOR (interferes with Uj active uptake of noradrenaline into noradrenergic nerve terminals). It is a VASOCONSTRICTOR and can be used as a topical mydriatic and ocular diagnostic agent. It is a powerful CNS stimulant (similar in action to amphetamine), with considerable abuse potential, cocaine hydrochloride cocaine. 

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