[Usefulness of apraclonidine in the diagnosis of Horner syndrome].

CASE REPORTS: We present four cases: two males with Horner Syndrome, who were diagnosed by means of apraclonidine 0.5% and cocaine 4% tests respectively. Two children with anisocoria, one of whom had Horner Syndrome confirmed with apraclonidine 1% and the other, in whom an apraclonidine test ruled out this syndrome but in whom pilocarpine 0.125% confirmed Adie's pupil. DISCUSSION: Apraclonidine drops (1% and 0.5%) may aid in the diagnosis of Horner Syndrome and are easier to obtain than cocaine.