Recurrent episodes of night blindness in a patient with short bowel syndrome

To describe clinical characteristics in a patient with recurrent episodes of night blindness due to vitamin A deficiency caused by short bowel syndrome in Crohn disease.

Retrospective analysis of best-corrected visual acuity (BCVA), kinetic perimetry, slit-lamp biomicroscopy, ophthalmoscopy, fundus photography, fundus autofluorescence (FAF), spectral domain optical coherence tomography (SD-OCT), dark adaptometry (DA) and electroretinography (ERG). Serum vitamin A level was measured.

A 44-year-old man with a 3-year history of night blindness suffered from a short bowel syndrome with chronic malabsorption due to ileocecal resection in Crohn disease. Both eyes had a BCVA of 0.9, Bitot’s spots of the conjunctiva and no significant fundus abnormalities. SD-OCT showed no remarkable changes, whereas FAF was brighter than normal in the center of the fovea. DA showed normal cone and a lack of rod function. The dark-adapted 0.01 ERG was non-detectable, the dark-adapted 3.0 ERG severely diminished, but the light-adapted 3.0 and 30 Hz flicker ERGs were within normal limits. Serum vitamin A level was 0.11 µg/ml (normal 0.30–0.65 µg/ml). Treatment with intravenous vitamin A caused a rapid recovery of night vision and ERG. However, during the following 3 years, he had three further episodes of night blindness with loss of rod function. During each period, parenteral vitamin A substitution brought complete recovery of night vision and rod function. BCVA, fundus, FAF findings and SD-OCT remained unchanged during the course.

In patients with known chronic malabsorption serum vitamin A level should be regularly checked to avoid recurrent night blindness episodes. ERG might be more sensitive than serum vitamin A level and is recommended in case of night blindness but still normal vitamin A level.