Decreased night vision: Vitamin A deficiency?
A 56-year-old woman reported for evaluation of decreased night vision. Her symptoms started about 2 months before her presentation, when she noticed spots of her vision were missing in dim lighting. Her surgical history was significant for Roux-en-Y gastric bypass.

The decreased vision progressed, and at the time of evaluation, she could not see to drive and required assistance with walking at nighttime. In bright lighting and during the daytime, she was asymptomatic. She had similar but milder symptoms about 1 year prior and felt they resolved spontaneously. Her vision was otherwise intact.

Visual acuities were 20/20 in the right eye and 20/20-1 in the left eye. Pupils were equally round and reactive without an afferent pupillary defect. OCT of the macula was unremarkable. Visual fields were normal. Full-field electroretinogram (ffERG) showed abnormal photoreceptor responses, with rods worse than cones.

DIFFERENTIAL DX
The differential diagnosis of decreased night vision (nyctalopia) is broad. Most commonly, it could be secondary to uncorrected myopia or cataracts.

In cases of true nyctalopia, many congenital disorders can be considered, such as congenital stationary night blindness (CSNB), fundus albipunctatus, Oguchi disease and retinitis pigmentosa (RP).

Choroideremia, gyrate atrophy and enhanced cone syndrome disease can also be included in the differential.

FINAL DIAGNOSIS
Given the patient’s history of Roux-en-Y-gastric bypass surgery, Vitamin A deficiency was suspected as the etiology of her visual symptoms. Vit. A levels were 5 µg/dL (normal levels 15 to 60 µg/dL). When she learned of the connection between the vitamin A levels and her visual symptoms, she recalled that when she was symptomatic the previous year, her vitamin A level was also low at that time, and after she received supplementation, her visual symptoms resolved.

Read more here: https://pxmd.co/fuX14
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