Vitamin A Deficiency Implicated in Unexplained Vision Loss

HOUSTON, June 13 - Unexplained vision loss may be related to vitamin A deficiency in patients with a history of intestinal or bariatric surgery, no matter how long ago, according to ophthalmologists here.

Vitamin A deficiency, once rare in the developed world, is becoming increasingly common with the growing popularity of bariatric surgery to treat morbid obesity, said Rod Foroozan, M.D., of the Cullen Eye Institute at Baylor here, and colleagues, in an online report in the British Journal of Ophthalmology.

The small intestine's ability to absorb vitamin A as either retinol or carotene, may be hampered by intestinal or bariatric surgery, said Dr. Foroozan. The fat soluble vitamin is necessary for the healthy working of photosensitive pigment in both rod and cone cells.

The Baylor report presented three case reports of patients 65 or older, who had extensive intestinal surgery 16 to 36 years earlier. The procedures included intestinal bypass, partial small- and large-bowel resection because of Crohn's disease, and gallbladder removal. One patient had a history of liver cirrhosis.

None of the patients had a significant family or personal history of eye problems, but all had had a recent decrease of vision or night blindness, or both. In one patient characteristic Bitot's spots were seen (areas of abnormal squamous cell proliferation and keratinization of the conjunctiva). All three patients were taking oral vitamin A supplements, but none was specifically treated for vitamin A deficiency.

Laboratory tests revealed that all had significant vitamin A deficiency, however, ranging from less than 0.06 mg/L of retinol to 0.09 mg/L. The normal range is 0.30 mg/l to 1.20 mgL.

Because of concerns that even high doses of oral vitamin A would not be absorbed efficiently by these patients, the patients were offered intramuscular injections of vitamin A. One patient refused the treatment, but vision improved for the other two within a week of the injections.

For patients with unexplained vision loss, Dr. Foroozan concluded, "our study suggests that even a remote history of intestinal bypass surgery, especially in the setting of comorbidities such as liver disease, should raise the suspicion of vitamin A deficiency."