Editor,—Maple syrup urine disease (MSUD) is an autosomal recessive disease associated with defects in the branched chain α ketoacid dehydrogenase complex. It may be divided into four major categories of classic, intermediate, intermittent, and thiamine responsive which carry differing symptoms and prognostic factors.1 Those patients diagnosed and managed early have an improved neurological outcome.2 Known ophthalmic complications which occur in untreated or late diagnosed patients include bilateral ptosis, ophthalmoplegia, nystagmus, strabismus, and optic atrophy.3 Cortical blindness has also been mentioned in the literature3; however, we failed to find any case reports confirming this.

At times of metabolic decompensation, oedema involving the deep white matter can be demonstrated on computed tomographic (CT) and magnetic resonance imaging (MRI). These abnormalities regress under dietary treatment, with clinical and neurological improvement.4

This report describes an infant diagnosed with intermittent MSUD at 6 months of age who had cortical visual impairment (CVI), with absent visual evoked potentials, and who showed clinical and electrophysiological improvement following dietary therapy.