Division of Oculoplastics Surgery, Wilmer Eye Institute, Johns Hopkins University, School of Medicine, Baltimore, MD 21287, USA.
To demonstrate the effect of apraclonidine on anisocoria and ptosis in Horner syndrome, one drop of 0.5% apraclonidine was instilled in both eyes of 3 patients who presented with acute Horner syndrome, and the effect on ptosis and anisocoria was documented. As reported in the literature, one drop of 0.5% apraclonidine reverses the anisocoria of Horner syndrome. In addition, 0.5% apraclonidine leads to a complete resolution of the ptosis associated with Horner syndrome, a finding reported once in the literature. Apraclonidine is a safe and readily available alternative to cocaine for the diagnosis of Horner syndrome.