Purpose: To evaluate the efficacy and safety of apraclonidine 0.5% in the diagnosis of Horner syndrome in pediatric patients.
Design: Prospective, interventional case series.
Methods: Ten pediatric patients with a diagnosis of Horner syndrome and 10 age-matched controls with physiologic anisocoria underwent pharmacological testing with apraclonidine. The difference between the pupil diameters of both eyes under low (room light off) and high (room light on) ambient illumination before and one hour after apraclonidine was instilled was recorded. Any adverse effects during the examination or reported by the patient's parents were recorded.
Results: The mean differences in pupil diameters before and after apraclonidine testing in the Horner syndrome group were -2.05 mm and 0.97 mm, respectively, under low illumination (P = .0049) and -1.48 mm and 1.1 mm, respectively, under high illumination (P = .0051). Three patients with Horner syndrome showed positive values (reversal of anisocoria) only under high ambient illumination, but not under low illumination. There was no statistical difference in the mean differences in pupil diameter before and after apraclonidine testing in the control group. Conjunctival hyperemia was noted in two patients with Horner syndrome and in three patients in the control group. No systemic adverse effects were noted during the examination or were reported by patients' parents.
Conclusions: The application of apraclonidine in pediatric patients is safe and effective in the diagnosis of Horner syndrome. The reversal of anisocoria was more obvious under high (room light on) ambient illumination.