A new study by U.S. researchers concludes that a boom in gastric bypass surgery could lead to an increase in vitamin A deficiency among patients that raise their risk for blindness.

The U.S. researchers studied the medical histories of patients who were nearly blind or had very poor eyesight but no family history of blindness.

Published in the current issue of the British Journal of Ophthalmology, the study focused on three patients over the age of 65 who were diagnosed with vitamin A deficiency and have undergone major intestinal surgery in the last 20 to 35 years.

The Health Day news says Vitamin A is required for the healthy maintenance of tissues and functions of the eye. The deficiency of Vitamin A leads to blindness or poor eyesight.

Patients in the study had either intestinal bypass or gallbladder surgery, or surgery to remove tissue damaged by inflammatory bowel disease. Though each patient had also taken vitamin A supplements, they still maintained poor eyesight.

It was also noted that when the patients received intramuscular injections of vitamin A, improvements in their vision was seen after just a few days.