Major intestinal surgery, including stomach reduction for obesity, may boost the chances of subsequent vitamin A deficiency, suggests a small study published in the British Journal of Ophthalmology.
The researchers base their findings on three patients with increasingly poor eyesight or night blindness, who attended a specialist eye clinic within the space of a year. None of the patients had a family or personal history of eye problems.
All three patients, who were all over the age of 65, had had extensive intestinal surgery between 20 and 35 years earlier.
The operations included intestinal bypass, surgical removal of diseased tissue as a result of inflammatory bowel disease, and gallbladder removal.
All the patients were diagnosed with vitamin A deficiency, and this was in spite of them having taken vitamin supplements.
One of the patients refused injections of vitamin A into the muscles. But the other two went ahead with this treatment, which prompted an improvement in their vision within days.
Vitamin A deficiency is the leading cause of childhood blindness in developing countries, and is caused by malnutrition. It is rare in affluent, developed countries, where it is mainly caused by poor absorption or abnormal metabolism.
A fat soluble vitamin, it is absorbed through the small intestine as either retinol or carotene, and stored in the liver for up two years and transported to tissues as needed.
Vitamin A is essential for the healthy working of the photosensitive pigment and superficial tissues of the eye. Night blindness is one of the most common symptoms of vitamin A deficiency.
The authors warn that the increasing popularity of gastric banding and gastric bypass, the surgical treatments for obesity, is making vitamin A deficiency increasingly common in the developed world.