Vitamin A is essential for the healthy working of the photosensitive pigment and superficial tissues of the eye," the authors explain. "Night blindness is one of the most common symptoms of vitamin A deficiency."
Vitamin A deficiency with night blindness has been reported in a number of patients who have malabsorption as a result of intestinal bypass surgery and, more recently, bariatric surgery," Dr. Rod Foroozan and Dr. T. Chae, of Baylor College of Medicine, Houston, report in the British Journal of Ophthalmology.
"In these reports, vitamin A deficiency developed within several years of gastric or intestinal surgery," they note. However, the team now describes three patients who developed decreased vision or night blindness decades after having extensive intestinal surgery.
All of the patients were older than 65 years and none had a family or personal history of eye problems. The surgeries included intestinal bypass 20 years earlier, partial removal of the intestines for Crohn's disease 36 years previously, and gallbladder removal 18-20 years before the deficiency diagnosis.
All of the patients were diagnosed with vitamin A deficiency despite taking vitamin supplements. One patient refused treatment with injections of vitamin A supplements. The other two subjects received this treatment, which resulted in improved vision within days.
"Our report illustrates that without a high degree of suspicion, vitamin A deficiency from chronic malabsorption may go unrecognized," Foroozan and Chae say, and "even a remote history of intestinal bypass surgery...should raise the suspicion of vitamin A deficiency."
The investigators add that because of the increasing popularity of gastric banding and gastric bypass, vitamin A deficiency is becoming increasingly common in developed countries.