Spinocerebellar ataxia type 1 (SCA1) is an autosomal-dominant, late-onset, slowly progressive disorder, primarily characterised by a gradual loss of motor coordination, resulting from dysfunction and degeneration of the cerebellum and its connecting pathways.^1,2 This disease is caused by expansion of a CAG trinucleotide repeat within the SCA1 gene, which encodes a protein called ataxin-1.^1,2 The first and most typical neurological symptom of SCA1 is cerebellar ataxia. Additional symptoms comprise the slowing of saccades, ophthalmoplegia, dysarthria, pyramidal sign and involuntary movement.^1,2 As regards ophthalmological abnormalities of SCA1, decreased visual acuity owing to optic atrophy, attenuation of oscillatory potentials of electroretinogram and enlargement of corneal endothelial cells have been reported.³ Hence, pigmentary macular dystrophy (PMD) has not been recognised as a clinical feature of SCA1, although it is well established as a major symptom of spinocerebellar ataxia type 7 (SCA7), which is caused by expansion of a …