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Experimental observation shows corneal swelling from low-tonicity tears produced by Allium cepa exposure, suggesting a novel mechanism.
Corneal thickening was produced experimentally in two subjects by the tearing associated with a noxious simulus (grated onions or Allium cepa ). The hypothesis is advanced that excessive tearing yields tears of lower than normal tonicity which in turn causes the corneal swelling.
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Chan et al. (1972) studied this question.
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