Ophthalmopathy due to environmental toxic substances especially intoxication by organophosphorus pesticides]

Organophosphorus pesticides (OPs) produce optico-autonomic peripheral neuropathy in human populations in districts where a large amount of pesticides have been used in agriculture. This report presents an epidemiological study that was performed in Kanagawa Prefecture. An autopsy case of a professional organophosphorus sprayer is reported. In addition, an experiment was performed to investigate a non-cholinergic chronic toxicity due to a certain OP. The epidemiological study revealed that 64 of 7,435 farmers showed vertical smooth pursuit defect of the eyes, impairments of modulation-transfer function (MTF) of the visual system and abnormal contraction dynamics of the pupil reaction to light stimuli, and a high residual level of OP was found in their blood. These abnormalities were reduced by treatment with antidotes such as atropine, prifinium bromide, and pralidoxime methiodide (PAM). The autopsy findings showed severe retinal degeneration with optic neuropathy and an obviously precocious progression of arteriosclerotic change in heart, brain, and retinal vessels. These findings can not be explained by cholinesterase inhibition alone. Experimental evidence showed that OP produced non-cholinergic impairment such as increase of Ca ions in retinal neurons. A generation of free radicals was noted in tissue-cultured retinal neurons. Blood selenium level was reduced by OP. These non-cholinergic actions may also explain the neural damage caused by long-standing low-dosage contact with OPs.