Doctor: Does frequent exposure to onions cause blindness?

Recently, public opinion has been stirred by the news that hundreds of people in the onion growing area have suffered vision loss, even blindness, due to long-term exposure to this agricultural product. Is there a medical basis for this?

There is no scientific evidence that onions cause blindness.

On July 25, specialist 2 Tang Hong Chau, Director of Saigon Cach Mang Thang Tam Eye Hospital, said that there is currently no medical evidence that long-term exposure to purple onions causes blindness or permanent damage to the cornea. However, continuous and unprotected exposure can cause temporary irritation, such as burning, watery eyes, red eyes, and even mild conjunctivitis if not properly cleaned.

There are no documented cases of permanent corneal damage caused by onions. However, there are some reports of allergic conjunctivitis, a persistent irritation of the conjunctiva, which usually resolves well after discontinuation of exposure or treatment.

Specialist 2 Doctor Tang Hong Chau analyzes the eye structure model

PHOTO: LE CAM

"The spiciness in onions is due to the enzyme alliinase, which is released when onions are cut or crushed. This enzyme produces propanethial-S-oxide - a volatile gas compound that stimulates the lacrimal glands, causing tears, stinging eyes and a burning sensation. If exposed multiple times a day, the eye mucosa may be slightly irritated, causing redness, fatigue or prolonged discomfort," Dr. Chau analyzed.

Many cases of eye injury due to occupational hazards

In clinical practice, Dr. Chau said he has encountered many cases of patients with eye injuries related to their occupations, from welders, carpenters to farmers, due to exposure to dust, chemicals or strong light without appropriate protective measures.

For people who grow or process onions, the risk is similar if they do not wear glasses or work in poorly ventilated environments.

"Common risks if people grow onions without protection include irritant conjunctivitis , dry eyes , or even mild corneal abrasions due to rubbing the eyes vigorously when they feel irritated. In the long term, if not properly cared for, it can increase the risk of infection or temporarily affect vision," said Dr. Chau.

The pungency in onions is due to the enzyme alliinase which is released when the onion is cut or crushed.

Photo: AI

How to prevent eye damage when working in dusty, spicy environments

"Exposure to onions does not cause blindness if properly protected. However, subjectivity, lack of protection and lack of attention to eye care can lead to long-term irritation problems. Caring for the eyes not only helps protect vision but also maintains the health of onion growers - a valuable traditional profession in many localities," Dr. Chau shared.

To prevent eye injuries, Dr. Chau recommends that workers wear transparent goggles while working to prevent dust and tear gas, wash their eyes with saline after each working day, do not rub their eyes with dirty hands, especially when they have just come into contact with onions; work in a well-ventilated area, or have an exhaust fan when peeling onions indoors. Use eye drops if you feel a lot of stinging and go to a medical facility if you have signs of prolonged red eyes or pain.

Can Tho leaders 'deny' information that many onion growers are... blind

As reported by Thanh Nien , on July 23, the City Party Committee, People's Council, People's Committee, and Vietnam Fatherland Front Committee of Can Tho City held a conference to meet businesses and investors in 2025. Representatives of more than 100 businesses and investors operating in the area attended.

At the conference, Mr. Le Xuan Dac, General Director of Dac An Investment - Production - Trading Company Limited (abbreviated as Dac An Company), said that Vinh Chau Town of Soc Trang Province (old) has about 4,000 - 6,000 hectares of agricultural land; of which about 1,700 hectares are used to grow purple onions. According to Mr. Dac's research, among thousands of farmers growing purple onions, about 1,200 people are blind due to the spicy substance from purple onions that damages their corneas. However, people here still consider this profession a traditional one, passed down from father to son.

However, according to Mr. Ngo Thai Chan, Director of the Department of Agriculture and Environment of Can Tho City, the story that growing purple onions leads to blindness is not true. About 20 years ago, people did not have a way to preserve purple onions, did not know how to protect their health, so it affected their eyes. But now, purple onion growers do not go blind in large numbers as recorded by Dac An Company.

Source: https://thanhnien.vn/bac-si-tiep-xuc-nhieu-voi-hanh-tim-co-gay-mu-loa-185250724232927928.htm