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Sir,

Vitamin A deficiency, a known complication after small bowel bypass surgery, is rare after large bowel bypass surgery. We report a case of Bitot spots on the conjunctiva secondary to vitamin A deficiency following right hemicolectomy.

Case report

An 81-year-old man, a known case of bilateral lower lid ectropions and bilateral age-related macular degeneration (ARMD), was referred to the eye clinic complaining of bilateral sore eyes for the last 4 months. He had undergone right hemicolectomy for Dukes B adenocarcinoma of ascending colon approximately 2.5 years ago, and since then was experiencing sporadic diarrhoea. His current medical prescription included oral loperamide and topical viscotear gel.

On ophthalmic examination, his best-corrected visual acuity was 6/18 in the right eye and 6/36 in the left eye. An anterior segment examination revealed foamy plaques on the bulbar conjunctiva temporal to limbus (Figure 1). The Schirmer test was within normal limits. There was diffuse punctate Rose Bengal staining of the conjunctiva. The rest of the anterior segment was normal. Dilated fundus examination showed bilateral dry ARMD. Anterior segment findings were consistent with vitamin A deficiency. When questioned, the patient did not complain of any night blindness. Dark adaptometry was however not performed. Serum levels of fat-soluble vitamins were performed. The serum vitamin A levels were 0.1 μmol/l (range 1.5–2.5) and vitamin E levels were 4.3 μmol/l (range 12.0–28.0). Other investigations, including FBC, U&E, LFTs, serum lipase, lipid profile, clotting time, vitamin B12, folic acid, and ultrasound of the abdomen, were all normal. He was commenced on oral vitamin A supplements 5000 IU three times a day. On examination, the Bitot's spots were still present at a follow-up appointment after a month when conjunctival biopsy was performed. This showed hyperkeratosis, parakeratosis, and chronic inflammatory infiltrates in conjunctival epithelium consistent with those seen in Bitot's spots. At 3 months following the commencement of the oral vitamin A supplements, the serum vitamin A levels became normal and the Bitot's spots regressed completely in 6 months time.

Figure 1
figure 1

Anterior segment photographs showing Bitot's spots.

Full size image

Comment

Vitamin A is a fat-soluble vitamin that is absorbed in the terminal ileum. Bile and lipase play an important role in the absorption of vitamin A across the intestinal wall. Once absorbed, it is stored mainly in the liver, where it provides a ready supply to serum. The liver store in a well-nourished healthy adult may last up till 3 years.1 A true vitamin A deficiency state results only after the vitamin stores in the liver are depleted completely. Although the main cause of vitamin A deficiency worldwide is malnutrition, in developed countries the cause is either malabsorption or inadequate storage.

Vitamin A deficiency has been reported in various gastrointestinal disorders, including Crohn's disease,2 cystic fibrosis,3 primary biliary cirrhosis,4 Jejuno ileal bypass surgery,5 and hemicolectomy.6 The clinical manifestations of vitamin A deficiency include night blindness, xerophthalmia, and follicular hyperkeratosis of the skin. Xerophthalmia ranges from mild conjunctival dryness to keratomalacia.

Impaired dark adaptation or night blindness is the earliest manifestation of the disease, but it is seldom noticed until it has become very pronounced.7 Conjunctival changes occur long before those in the cornea and clinically appear as lustreless conjunctiva. Occasionally, the conjunctiva in addition to being xerotic exhibit foamy plaque on the bulbar conjunctiva known as Bitot spots. Histologically, Bitot's spots show hyperkeratosis, parakeratosis, and loss of goblet cells.

There are only two previously reported cases of vitamin A deficiency after hemicolectomy.6,8 Both cases had night blindness as the only ophthalmic manifestation. One of the cases8 had radiation enteritis as the main cause of vitamin A deficiency. The case here is unusual because he presented with Bitot's spots as the sole clinical manifestation of vitamin A deficiency. The patient might have poor dark adaptation, but when questioned he denied any night blindness. This may, of course, be due to his already poor vision because of ARMD. As a result of his old age and poor vision, dark adaptometery was not performed.

This patient developed vitamin deficiency 2.5 years after right hemicolectomy, which indicates that his presumed diet was healthy and his liver functions were normal.1 There was no clinical or biochemical evidence of generalized malabsorption or liver and pancreatic disease. In the case where a short bowel resection has been performed, the cause of vitamin deficiency is well understood because of the removal of the absorptive surface. The cause of vitamin deficiency in hemicolectomy is uncertain, but it may be related to decreased transit time through the small intestine owing to gut hypermotility. Chronic diarrhoea and the continued use of laxatives have been implicated as the cause of vitamin deficiency.9

Our patient did have chronic diarrhoea since the operation, and we feel that gut hypermotility was the cause of his vitamin A deficiency. The reason why the patient only had a fat-soluble vitamin deficiency is that, in mild intestinal absorption disorders, it is the fat-soluble vitamins that are least well absorbed.10

In summary, this is the first reported case of Bitot's spots following hemicolectomy.