Guideline may help in prescribing vigabatrin

EDITOR —In 1997 a severe visual field defect was reported in three adults who had taken vigabatrin for two or more years.1The following is a consensus guideline from a paediatric advisory group addressing the prescription of vigabatrin in children.

(1)The defect seems to be specific—a bilateral and symmetrical peripheral constriction with relative temporal sparing which,rarely, may be severe. The incidence in adults is estimated to be 10-20%. Its pathogenesis is unclear; it may or may not be reversible.The defect is not reliablyidentified by confrontation testing.

(2)If …