Aqueous humor dynamics in a series of patients with third neuron Horner's syndrome.

We studied aqueous humor dynamics in a group of 21 human subjects, each of whom had third neuron Horner's syndrome in one eye and a normal fellow eye. The diagnosis had been made at least four months before this study began. We estimated the degree of involvement with Lowenstein-Loewenfeld pupillography with and without hydroxyamphetamine. Surprisingly, aqueous humor dynamics were normal in the eyes with Horner's syndrome. The mean intraocular pressure was 1 mm Hg less than that of the normal eyes. Aqueous humor flow and tonographic facility of outflow were normal, as was the response to the beta-blocker timolol. However, the response of the eyes with Horner's syndrome to epinephrine was abnormal. The normal eyes showed an increase in aqueous humor flow after epinephrine administration and the eyes with Horner's syndrome showed a decrease.