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Onions: The Real Tear-Jerker | Long Island Eye Doctor

Onions:  The Real Tear-Jerker
Suchi Matalia, OD

Ever wonder why we start crying when chopping up onions?

Cells, which are irritating to the eye, are released from the vegetable when an onion is cut into. Onions are part of a plant family (same as garlic and chives) that absorbs sulfur in the earth, which forms a class of volatile organic molecules called amino acid sulfoxides.  Sulfoxides are the cells released from the onion which are aggravating to the eye.

Any irritation to the eyes, including dust or smoke, causes the eyes to shed tears.  These tears, known as reflex tears, are regulated by the lacrimal glands.  When an external irritant is around, the nerve endings in the cornea communicate with the brain.  The brain registers the irritation and tells the lacrimal gland to release tears to alleviate the burning sensation.

You can avoid watery eyes doing some of the following:

  • Wearing safety goggles
  • Keeping a fan on close by
  • Refrigerate the onion before cutting
  • Cut the onion under water
  • Wear contact lenses

Dr. Suchi Matalia

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