Background: Rapidly progressing bilateral night blindness in an elderly patient suggests primarily a diagnosis of paraneoplastic retinopathy. Occasionally diffuse rod dysfunction can result from vitamin A deficiency.
History and signs: A 70-year-old man complained of progressive night blindness and xanthopsia for the past 6 months. Visual acuity was 0.8 in both eyes with severe dyschromatopsia. Slit-lamp and fundus examination were normal. Visual field disclosed bilateral depression. Scotopic full-field ERG was severely reduced. The patient's medical history revealed an acute pancreatitis one year ago, followed by chronic jaundice and an increased blood bilirubin. Serum vitamin A level was decreased to 0.1 micromol/L (normal range 1.5 to 4.0).
Therapy and outcome: Intramuscular injections of vitamin A were provided. Subjective visual improvement was reported already one day after initiation of therapy. Scotopic full-field ERG was markedly improved 3 days after the injection and was only slightly subnormal 3 months later.
Conclusions: In developed countries, vitamin A deficiency usually results from malabsorption syndromes and manifests initially by rod more than cone dysfunction. This diagnosis should be entertained early as vitamin A supplementation induces a rapid restoration of vision.