Peripheral visual field defects in patients taking vigabatrin seem to arise in a proportion of patients. Typically a concentric narrowing of the field is seen with preservation of central acuity and colour vision. Case definition remains poorly defined and prevalence figures ranging from as low as 0.14% to as high as 39% have appeared.1 2 The high figures reported by Lawden et al, this issue, pp 716–722,3 reflect a definition which includes any bilateral field defect that could not be explained in terms of other retinal or neurological pathology regardless of severity of symptomaticity. This clearly highlights the problem but leaves more work to be done.

Visual field …